Astronomy/Questions Answered by Expert Philip Stahl

SubjectDate Asked
Cheap Telescope3/7/2017
  Q: If someone used the lowest quality lens out there to make it more cost affective how expensive would ...
  A: First, before giving a direct answer let's look at some applicable quantities. These include the ...
Probability2/22/2017
  Q: I see articles from time to time about how they came to the conclusion that Pluto should be ...
  A: and thanks for your question. First, the decision to reclassify Pluto - unbeknownst to many - was ...
Kepler's laws2/19/2017
  Q: Dr.Fitzpatrick have read my arguments.But he declined to continue corresponding; he could not ...
  A: I already told you and SHOWED you that you CANNOT have a perpendicular vector (or scalar) value to ...
Moon photograph10/18/2016
  Q: I'm trying to take a photo of a full moon over the ocean. The photo I want to create is of the moon ...
  A: Bear in mind the full Moon sets when the Sun rises. This means your photo would need to be takn in ...
space telescopes8/13/2016
  Q: Why are Hubble's optics enclosed in a tube with a door, and the upcoming James Webb design is ...
  A: The Hubble's optics are enclosed because its aperture at 2.4 m (7.9 ft.) made it more practical to ...
HELP2/23/2016
  Q: sIR I WNAT TO KNOW WHAT IS DIFFERENCE BETWEEN ASTRONOMY AND ASTROPHYSICS.
  A: There is actually very little difference, given most of modern astronomy is also grounded in modern ...
Accelerating Universe2/5/2016
  Q: Mr Stahl, Please forgive me, I barely passed high school although I'm a professional pilot. 61 y.o. ...
  A: and thanks for your question. Actually, to the extent we trust our measurements (including for the ...
Flyspeck: small light rocketship designed by Sagan?12/11/2015
  Q: A long time ago, Carl Sagan and other physicists had the idea of taking a very light ?space ship? ...
  A: I have never heard of any project or craft by the title 'Flyspeck'. I believe what you may be ...
Fool Proof11/27/2015
  Q: Wondering, I think I saw two different models for a Geocentric universe. Then there's the ...
  A: I am assuming in this question that what you really mean is "different models for the solar system". ...
importance of Keplers second law11/8/2015
  Q: how much Kepler's second law is important in space science? how are you using it in launching space ...
  A: Kepler's 2nd law is extremely important in the discipline of celestial mechanics which is concerned ...
Objects that have impacted the earth...10/20/2015
  Q: Greetings! I have a relatively simple question but have been unable to find the answer after ...
  A: The ability to track objects that are potential impactors is extremely limited and I know of no ...
rotation of the Sun8/21/2015
  Q: Obviously, the rotation of the Sun around the Galactic Center will generate a centrifugal force ...
  A: Points addressed: 1) There is no such force as "centrifugal force". The correct force is ...
your openion8/14/2015
  Q: When I asked you if the diagram showing the sun in the center of the orbit is violating Kepler's ...
  A: You wrote: "since you insist that the four quarters of orbit space are equal, do you agree that the ...
Kepler 12 equal areas8/10/2015
  Q: According to geography, the Sunlight through the four seasons must be: 1- Orthogonal to the tropic ...
  A: I'm sorry but the link you provide on the equal areas shows (to me) no such evidence that: "the two ...
I have read your aswer8/9/2015
  Q: I have read your answer to my follow up question although the focus where the Sun must be is closer ...
  A: Sorry, but I don't give out my personal email. Let me just say that I believe the problem is you're ...
an image incompatible with Kepler first law8/7/2015
  Q: If we agree that the famous image of four seasons in the link below is wrong because it violates ...
  A: Given the Earth's orbit is nearly a perfect circle (eccentricity e = 0.0167) one can say the drawing ...
Earth orbit8/2/2015
  Q: Mr.Stahl, recent photo of the ISS in front of the moon, brought back the memory of a night in 1987 ...
  A: Your sighting sounds intriguing- but in order to really address it I'd have to see all ancillary ...
infinity & the universe7/12/2015
  Q: when i say the universe is this understood to be an infinite propitiation ( no beginning, no middle, ...
  A: In current standards of astronomical parlance when one uses the term "universe" it refers to a ...
solar flares & gravity6/29/2015
  Q: Please excuse any scientific misunderstandings beforehand: When I watch footage of solar flares it ...
  A: In actual, technical fact gravimetric forces are found throughout space, just at different ...
How to defend against WR 104?6/16/2015
  Q: let's say we are somewhat more advanced then today and WR 104 gamma burst is coming, could we defend ...
  A: When those in the know say a GRB from WR 104 is "coming" they really mean any time from today to ...
the orbit of earth4/2/2015
  Q: I am in Australia, and I have been learning about the Earth's orbit around the Sun, and I noticed ...
  A: I think this previous answer can help to shed some insight, ...
Orange dwarf stars etc.1/17/2015
  Q: It has been mentioned many times that the most likely solar systems with life on some of the ...
  A: I am not sure you're aware, but the number of "habitable" planets found thus far is exceedingly ...
astrophysics11/19/2014
  Q: Was the star which exploded and became the crab nebula a traveling mas which hit a space rock and ...
  A: In answer to your first question, there was no collision with a space rock, the star collapsed on ...
Laser pointers10/31/2014
  Q: I am researching to buy my husband a laser pointer for C'mas. He enjoys pointing out the night sky ...
  A: While I myself have not used laser pointers, amateurs I know in the Barbados Astronomical Society ...
Temperatures on Mercury7/29/2014
  Q: My question is about the temperatures on Mercury. The Mercury is really a very interesting case due ...
  A: Your question actually encapsulates a frequent misconception to do with astronomical measurements, ...
nicks reply to question7/6/2014
  Q: What if there is no rush for you to answer the two questions, these questions are really important ...
  A: Nick, Having just watched the Youtube video, I come away with the conclusion the whole thing is ...
How Many Multiverses Are There? Space Sizes Shapes Quality Quantity Eternity Infinity Hera Milky Way Galaxy Andromeda Serpents Part Of? Names Multiverses Galaxies6/26/2014
  Q: How Many Multiverses Are There? Space Sizes Shapes Quality Quantity Eternity Infinity Hera Milky Way ...
  A: As far as we know, there are no Multiverses! The concept so far is entirely a speculative one for ...
planetary nebulas6/11/2014
  Q: Why do 5 solar mass stars form planetary nebulas, (thus shedding their mass and allowing them to ...
  A: The issue of solar mass thresholds for stars - i.e. whether they become neutron stars or black holes ...
Earth's Axis Shift and Climate3/5/2014
  Q: I've just read your reply about this subject. You say that it's a "theory" only and then you go on ...
  A: I pulled up the full answer in my original response and the term I used to describe the external ...
Is there a safe way to view the sun without projection?2/23/2014
  Q: I have a Celestron Astromaster 70AZ refractor telescope given to me as a gift a. At first I just ...
  A: I think this site for 'Sky & Telescope' has perhaps the best guidance and also how to use the ...
Idea for a telecope2/11/2014
  Q: I thought of a great idea. At night, can a solar heating array, such as this one in Spain: ...
  A: An interesting idea but I don't think it would work, for several reasons. First, solar radiant ...
Astronomy, specifically involving Earth to Sun relationships1/2/2014
  Q: I understand that if the Earth were to cease revolution around the Sun, it would then be pulled into ...
  A: Rather than 're-invent the wheel' as it were, can I point you in the direction of an already fairly ...
Earth's rotation12/28/2013
  Q: I know this is a very silly question, but could you please tell me if it is just the tilt of the ...
  A: Liz Actually no, there are very few 'silly questions'. Those types are the ones provided without ...
What is the logic behind the Hill Sphere?12/15/2013
  Q: According to Wikipedia, Hill Sphere is : the volume of space around an object where the gravity of ...
  A: First of all, the gravity of a less massive object can dominate the gravity of a more massive one if ...
sun11/16/2013
  Q: we know that the sun makes different sounds from its magnetic loops ,but can it make all the sounds ...
  A: The 'sounds' to which you refer are acoustic waves. The Sun's acoustic waves usually start at the ...
space11/13/2013
  Q: Why astronauts feel weightlessness in space? A free falling body will have accelaration of g ...
  A: Weightlessness, the sensation of it, is a result of the absence of a reaction force to one's weight. ...
How do we really know what stars are?10/26/2013
  Q: All we are receiving from the objects we call stars is energy signals (light, gamma rays, etc.). We ...
  A: Interesting question- after I had to radically alter my mental perspective!This perception is in ...
Einstein-Rosen Bridges and Singularity9/7/2013
  Q: I've been fascinated with black holes and Einstein-Rosen bridges/wormholes for a long time. However, ...
  A: and thanks for your question! Alas, the wormhole concept is a very tricky one and also not fully ...
Worlds in Collision8/31/2013
  Q: Is there any merit at all to the theory of Immanuel Velikovsky in his book Worlds in Collision that ...
  A: No, there' no merit at all# It's a totally preposterous theory# For anyone not aware, ‘Worlds in ...
physics7/30/2013
  Q: Is there any perfectly black body exists? If yes, then the black holes in the space are perfectly ...
  A: No, a "perfect black" body doesn't exist, but stars come fairly close. According to thermodynamics ...
Portable Telescope introduction in High Schools.7/18/2013
  Q: https://en.wikipedia.org/wiki/Astronomy https://en.wikipedia.org/wiki/Telescope ...
  A: Here are the answers to your questions: 1) Telescopes can certainly be introduced in Optics ...
Order of creation7/16/2013
  Q: Could you please tell me whether the land mass appeared on earth prior to water OR water was there ...
  A: The origin of the continents as well as oceans remains a vast area which is still fraught with much ...
Jason astronomical7/15/2013
  Q: I have a Jason Astronomical discoverer model 313 wooden tripod pretty good condition what do you ...
  A: This is a difficult question to attempt to answer without actually seeing the tripod, trying it out ...
Describe what the Sun would look like from Earth if the entire photosphere were the same temp. as a sunspot?3/30/2013
  Q: Describe what the Sun would look like from Earth if the entire photosphere were the same temperature ...
  A: The range of sunspot temperatures is from 3000 K - 4500 K, while the normal photosphere is ...
how massive can a planet get?3/28/2013
  Q: how massive can a planet get before it becomes a star? what is the maximum mass for a solid planet?
  A: Alas the answer to your question is fraught with lots of uncertainties! In other words, there's ...
Midnight in Paris3/22/2013
  Q: Philip, I was wonder if see the star/ constellations in the skies of Paris for example in Jan 1, ...
  A: Paris is at approx. 49 degrees North latitude while Tokyo is at 35 N. So Tokyo is considerably ...
Moon on it's back3/18/2013
  Q: Yes, I read your answer, but the question really was : Is it a WINTER phenomenon in the hemisphere ...
  A: What you have uncovered is the role of latitude in relation to the observer's 3D orientation, i.e. ...
Southern Cross3/13/2013
  Q: I will be in Hawaii on the island of Hawaii, and I've been told that in the spring you can see the ...
  A: This previous answer: http://en.allexperts.com/q/Astronomy-1360/2011/3/Southern-Cross.htm should ...
Movement of the Sun through space3/10/2013
  Q: I wonder if you could please tell me the angle of inclination between 1) The Ecliptic Plane and 2) ...
  A: The first question is problematic since it presumes a relatively set plane of Earth's orbit (and ...
Photons2/24/2013
  Q: Does all photons travelled with the same speed? Photon emitted by our SUN (yellow Dwarf star) & ...
  A: Most photons travel at the same speed, c, but there are exceptions to be aware of. You should find ...
Big Bang2/22/2013
  Q: With all the new Technology and space Telescopes, I would like to know the location of the initial ...
  A: Actually, one of the biggest myths of space science-astronomy is that there is a "location" or ...
The "look-back time" concept2/1/2013
  Q: I am a chemistry undergraduate student. I have recently encountered the concept of "Look-back time" ...
  A: What you are referring to is basically, cosmic expansion - the expansion of the universe. It is ...
Galaxy Question1/29/2013
  Q: Good day I recently read that there are more than 100 billion galaxies in the universe. 1. How and ...
  A: First of all, given the uncertainties all we can do as astronomers is make our best guesses in terms ...
Moon turns1/27/2013
  Q: This is probably a dumb question, but how often does the moon turn circularly from an earth ...
  A: Actually, no. There's no evidence of which I'm aware of any such 'turning', apart from the motions ...
Habitable zone1/23/2013
  Q: I am planning to go to an observatory in Vienna, Austria at some stage. I was wondering if you knew ...
  A: Here's a brief summary of events coming up during the year: - Perseid meteor shower in August, and ...
Gamma ray bursts11/24/2012
  Q: A recent museum visit introduced me to a theory that Earth's Ice Ages were caused by gamma ray ...
  A: Geoff! To tell the truth, I'm always leery of assorted espoused 'theories' that somehow never made ...
Phobos and Deimos11/23/2012
  Q: Philip, I often hear of Phobos and Deimos being pulled in opposite directions by tidal forces, due ...
  A: You write that you've "often heard" of Deimos and Phobos "being pulled in opposite directions by ...
star or planet11/18/2012
  Q: I was recently in Cobo Mexico and we were having a debate about planet vets star or poss something ...
  A: Without a photo and a star background, to identify the constellations in the vicinity, it's ...
Star Clusters & Gravity11/15/2012
  Q: Why doesn't the force of gravity cause open & globular star clusters to collapse to a central point? ...
  A: The short answer to that (I will also give a longer, detailed answer) is that: a) gravity is too ...
Re. Picture11/11/2012
  Q: I'm Gus, from the question on the picture yesterday. Here's some extra information about the ...
  A: I checked using my Cybersky program for your location, and found that the planet Jupiter is ...
Object in the sky11/11/2012
  Q: I took this picture from, Garrison, NY, north of NYC. There were many other stars visible, but my ...
  A: Hell, Offhand, I wouldn't be able to say what the object is without knowing it's altitude, azimuth, ...
Moon Phases10/30/2012
  Q: Why do we have moon phases?
  A: Actually, the real question here is 'HOW do Moon phases occur?' since in science 'why' questions are ...
Asteroid10/12/2012
  Q: How much damage could this asteroid ...
  A: We look to the "Torino scale" of asteroid devastation, which is something analogous to the Richter ...
How do you figure out what angle the Sun should be at in the sky, for a certain time/place?10/8/2012
  Q: Hi there! To make a long story short, I’m trying to figure out if these rock boulders in the ...
  A: Your question and pic poses an interesting conundrum. Knowing at least the latitude and time of ...
Civil( BS) to Astronomy8/6/2012
  Q: I have bachelor of Civil engineering, how can I apply for master of Astronomy?! I want to continue ...
  A: The primary problem here is that the core of courses required of a civil engineering student are not ...
lightning7/28/2012
  Q: can you please tell me what I saw, I was in England in the mid 70s and was walking home as a thunder ...
  A: From your description, it sounds to me like you witnessed ball lightning, also known as kugelblitz. ...
Telescopes etc.7/22/2012
  Q: I was wondering if it would be actually possible for a small futuristic spaceship to leave the ...
  A: The way the Earth is covered by surveillance satellites and intelligence gathering outposts ...
Speed of Earth in the beginning7/7/2012
  Q: I had watched a documentary named (First Life) by Sir David Attenborough in which he said that in ...
  A: Yes the Earth rotated much faster some 3.5 billion years ago, about one rotation every 6 -7 hours. ...
Rogue Star7/4/2012
  Q: I was checking a game on the astronomy workshop website which was about calculating the orbit of a ...
  A: Hmmmmm.....for the mass of the component (~ 1 solar) I'd have expected about twice those distances ...
leap second7/3/2012
  Q: Here's hoping you know the answer to this one. A couple nights ago, on the news, there was a story ...
  A: Yes, there have been a number of colorful or 'cutesy' fables spun to try to describe what happened ...
Moon Exploration / Missions6/1/2012
  Q: http://en.wikipedia.org/wiki/Exploration_of_the_Moon http://www.engology.com/Apollo11.html ...
  A: Answering your questions in order: 1) In recent years, e.g. at least since the 1990s, there've been ...
Astronomy Issac Newton Question4/25/2012
  Q: What two major preoccupations did Newton devote himself to after the bulk of his scientific work was ...
  A: I'm not sure about precisely which two occupations Newton devoted himself to, but we have enough ...
about our sun4/7/2012
  Q: what is really going to happen to the sun after the heavy and gigantic flares that caused too much ...
  A: While the energies of CMEs (coronal mass ejections) and flares (even large ones) are significant - ...
Pluto3/16/2012
  Q: Why is Pluto no longer a planet?
  A: Pluto was "demoted" from its former status as a planet, basically as a result of a vote at a meeting ...
speed of fastest traveling celestial stars or galaxies3/2/2012
  Q: I would like to know at what rate of speed the fastest star or galaxy is traveling away from the big ...
  A: First, for sources receding at relativistic velocities, viz. v ~ c, the recessional velocity ...
crescent moon lying on its back2/24/2012
  Q: This has been happening for at least three years now, and for the last 3-4 months in a row. You have ...
  A: The crescent Moon "lying on its back" is really not so strange. Consider the first simple diagram ...
Cosmic rays and climate change1/1/2012
  Q: A few months ago there were some reports in the media that a group at CERN doing cloud chamber ...
  A: I believe you are referring to the 'CLOUD' experiments conducted by a team at CERN headed by Jasper ...
celestial coordinates12/30/2011
  Q: I know about the celestial coordinate system, i.e., that declination means degrees above the ...
  A: The most straightforward way to make conversions between any two coordinate systems is to use a ...
Earth's North Pole in Relation To Milky Way Center12/16/2011
  Q: What is relation of the earth's north orientation (i.e. Polaris) to the center of the Milky Way? For ...
  A: From Norton's Star Atlas, there is a "Galactic Chart" which shows the celestial coordinates of the ...
science fair project12/12/2011
  Q: My science fair project is calculating the average angle of the sun year round in Utah. Last year my ...
  A: You do not give your specific location (longitude, latitude) but I used the latitude for Salt Lake ...
earth and planitary science12/8/2011
  Q: How does the tilt of earth's axis affect the seasons?
  A: Interestingly, I was certain I'd answered this question already several years ago, but on going ...
New Earth-like plant discovered12/7/2011
  Q: A new Earth-like planet has been discovered, c.600 light years away. Based on the information in ...
  A: The mean temp. of this new planet has been given as about 72F, but so far none of the sources I've ...
Things to do on a budget.....11/12/2011
  Q: Several of my friends and I have a lot of interest in astronomy and wish to get into backyard ...
  A: There is certainly much to do beyond simple "looking at things". Today, the most relevant role for a ...
Nuclear Fusion in the Sun11/5/2011
  Q: since fusion is a fast chain reaction, I don't understand why hydrogen will remain unconverted to ...
  A: The problem is one first broached and explored by Prf. Martin Schwarschild in his excellent ...
Stone From The Ocean9/2/2011
  Q: I found this stone in the ocean at Rockaway beach, N.Y., after the earthquake and days after ...
  A: Alas, I declined the rating system from about 2 years ago because I found most questioners didn't ...
Astronomy9/1/2011
  Q: I am in the final year of school. After school what subject should i choose to do graduation so that ...
  A: First, realize astronomy is just physics applied to a space setting. Hence, all the key principles ...
Comets8/27/2011
  Q: I was reading a book online called Comets II and the following is a calculation of how much mass is ...
  A: The quantitative mass loss rate to which you referred is actually not an equation per se, but a ...
Comets8/23/2011
  Q: I have been trying to find out where exactly Jupiter family comets and Halley family comets come ...
  A: As your question discerns, there's a vast amount of uncertainty in terms of comets, their origins ...
big bang8/21/2011
  Q: my question is,was the formation of galaxies a mere accident after big bang or was it ...
  A: If there was another Big Bang (which is doubtful, because all the recent measurements and data show ...
Venus8/19/2011
  Q: If the planet Venus had had the same type of atmosphere as Earth, so never any greenhouse effect, ...
  A: This is an intriguing question, especially since as a purely hypothetical one we'll never know if ...
orbital speed, etc.7/14/2011
  Q: Stahl, Can you answer a few basic questions for me? My brother and I are having a debate about ...
  A: Okay let me give a comprehensive answer, first from a general (elliptical orbit) point of biew ...
regarding matter and antimatter7/10/2011
  Q: sir, we know that among matter and anti matter nature seems to prefer matter. why is this so? also ...
  A: Truthfully, we don't know WHY there is this asymmetry, but it may have something to do with Fitch ...
Calculation6/26/2011
  Q: What would be your "shorthand" calculation of the angular momentum of our galaxy?
  A: Basically, taking the galaxy as a thinnish disk, for which the moment of inertia is: I = ½ mR^2 ...
Twinkling stars and seasons in the earth5/12/2011
  Q: Question1: If the cause for stars to twinkle is the earth's atmospheric interference, then why do ...
  A: 1)Stars, first of all, cannot actually be seen, i.e. as the real, discrete objects we think we see. ...
orbits5/1/2011
  Q: good day i wonder if Kepler or any astronomer after him have gave any explication, why orbits are ...
  A: It is plausible that Kepler might have an inkling as to the physical basis for elliptical orbits, ...
supersonic solar wind4/7/2011
  Q: I have a quick question regarding the solar wind, I keep reading that it is supersonic, which by my ...
  A: You are technically correct that the terrestrial sound speed isn't relevant outside our atmosphere. ...
Red Giant Pahse of Sun3/29/2011
  Q: It may be odd question, but I wanted to know Is the Red Giant phase of our SUN will affect the ...
  A: Actually, the putative effects on Earth you describe are all, in a way, academic. Since the Sun in ...
clarification3/28/2011
  Q: Let me help you for an answer. I am of the (new) theory that Suns shed/eject/birth Suns. We now ...
  A: NO, Rob, my replies aren't "condemning" only calling out baseless speculations where and when I see ...
What If ?3/24/2011
  Q: I no that we don't have a full vu of what is really out there but just the part that I saw it looks ...
  A: The problem underlying your conjecture is that it's based only on how things look, which is a very ...
carrier in astronomy3/15/2011
  Q: what are the opportunities for an electronics engineer in the field of astronomy?
  A: I don't really see any such opportunities (other than in a kind of maintenance capacity, say for the ...
Southern Cross3/14/2011
  Q: What will be the best viewing dates for the Southern Cross on Maui this spring in 2011? Thank you ...
  A: According to my Cybersky program, ideal seeing (meaning enough altitude above the southern horizon) ...
Earth Orbit / Frame of Reference3/3/2011
  Q: Our earth is moving with 19 miles/sec on its orbit so the atmosphere around it and every object is ...
  A: It is impossible for the Space shuttle to "go out of" the Earth's gravitational influence, because ...
Isolated stars3/3/2011
  Q: In science fiction stories, there is a common theme which involves events surrounding a random ...
  A: Actually, I'm not aware of any science fiction stories that have such a "common theme". Can you ...
red flying light2/15/2011
  Q: Last night I was out side and heard what sounded like a jet to my dad and when I looked I saw a ...
  A: It's impossible to say definitively what it was (though at first pass, it sounds like some kind of ...
red dwarf comet clouds2/6/2011
  Q: If Red Dwarfs lack Hydrogen, would their circumstellar cloud also have a reduced relative amount ...
  A: It's hard to conceive that circumstellar clouds will be sustained around any red dwarf stars, far ...
Solar Flares1/31/2011
  Q: I was wondering what are the effects of solar flares on a carbon based satelite that orbits in space ...
  A: The effects of any flare will depend in general on its energy class. (Whether "carbon-based" or not, ...
Space Physics1/6/2011
  Q: I want to know how to measure or may be there is a website that give a data on the most recent total ...
  A: Unfortunately, I'm unaware of any sites that provide specific "data on the most recent total ...
Post Graduation in Astronomy after Bachelor's in Engg and Work1/2/2011
  Q: I have just finished my Bachelor's Engineering in Electronics and Instrumentation from Dubai but I ...
  A: Well, writing as one who's actually done that, all I will say is that it's rather difficult to do ...
Is the universe rotating?12/26/2010
  Q: I have finally gotten around to reading "A brief history of time". There was one statement in ...
  A: Actually, I just consulted my copy of 'A Brief History of Time' (Chapter 10, 'The Unification of ...
azimuthal coordinates of object between range of dates12/19/2010
  Q: I have the equatorial (/galactic) coordinates of an cellestial object of interest. I need to plot on ...
  A: The only program I'm familiar with is Cybersky which allows a direct conversion of a given object's ...
Gemini12/15/2010
  Q: How many stars (in total) are in Gemini?
  A: Technically, your question is impossible to answer since you are referencing an area of the sky that ...
astronomy12/11/2010
  Q: one day of earth is equal to fourteen days of moon.how is it possible?please explain it with ...
  A: There is no mystery at all to differing day lengths -and no need even for "proof". Because the "day" ...
astronomy12/11/2010
  Q: what is the relationship of time and gravity?what is the reality of time dilation in space?
  A: Hello, "Gravitational time dilation" refers to a slowing down of clocks in a gravitational field. ...
Space bubble12/6/2010
  Q: I read the article regarding space bubble and did net search regarding it. What i wana ask is that ...
  A: Re: "space bubble" I presume you're referring to LHA 120-N 11, N11 otherwise known as "the bean ...
astronamy11/17/2010
  Q: could you please tell me the distance from mercury to earth and mercury to sun?
  A: In terms of their mean distances (or what we call semi-major axes) - bearing in mind the distances ...
earth relativety to the univers11/9/2010
  Q: Long have we been told that the universe is actually moving away from us,,...and thats it. We are ...
  A: First, of all let me attend to your last query first: science (in this case cosmology-astrophysics) ...
light11/9/2010
  Q: IF LIGHT CAN'T ESCAPE A BLACK HOLE THEN DOESN'T LIGHT HAVE TO HAVE WEIGHT FOR GRAVITY TO GRAB ON TO ...
  A: Actually, since Einstein's seminal paper (on the inertia of energy) we know that photons (at least ...
Flame in the sky10/31/2010
  Q: my father called me outside to look at something in the sky, when I got outsid there was a very ...
  A: As this conforms to what I call a "transient unknown optical-atmospheric phenomenon', it is ...
Orbital Mechanics10/8/2010
  Q: I was reading about water being discovered on asteroids and it got me thinking about this crazy ...
  A: Of course, a 10 mile diameter asteroid is a veritable "planet killer" - likely much bigger than the ...
red shift10/3/2010
  Q: If a star or galaxy is moving away from us or moving toward us, I can understand the change in the ...
  A: Actually, if such a case were to occur (dynamically doubtful when one examines the kinetics of ...
pioneer space craft10/2/2010
  Q: what could cause the 2 pioneer space craft to be slowing down in a way not yet explained?
  A: I think you're probably referring to the so-called "Pioneer Anomaly". Probably the simplest way to ...
MILKY WAY10/1/2010
  Q: WHAT IS THE DARK RIFT IN THE MILKYWAY?
  A: Basically, the "dark rift" (or "great rift" as it's also called) is an obscuring, non-radiating ...
Time Dilation and observed velocity9/29/2010
  Q: In a previous question about time dilation ...
  A: Of course, the latter is true - since travel at superlight speed is simply not on. The key point is ...
Solar Energy that reach earth9/24/2010
  Q: What is the estimate of solar energy that reaches the Earth's surface? What amount of that energy is ...
  A: About 1360 watts per square meter, or 1360 Joules per sq. meter per second of solar radiant and heat ...
universe9/22/2010
  Q: A solar system, made up of planets and, at least, one star, exists with other solar systems in a ...
  A: Of course, the fact that there are multiple solar systems has nothing to do (logically or otherwise) ...
How to start study astronomy after engineering?9/13/2010
  Q: Sir, i am in final year of civil engineering and i want to study astronomy through distance ...
  A: You don't indicate to what level you wish to pursue astronomy education. To graduate level ...
space and transmission of lasers and microwaves9/8/2010
  Q: If I have a microwave and a laser, and I point them up and into space, assuming no real interference ...
  A: You propose an interesting hypothetical, however it's not hypothetically realistic! (In this regard, ...
Planetary stripes9/5/2010
  Q: How do planetary stripes form, and why specially in planets after jupiter only?
  A: By "planetary stripes" I believe you mean the *atmospheric belts* that are visible in all the Jovian ...
Making a diagram of the solstices and equinoxes8/29/2010
  Q: What is the best way to illustrate in a diagram the eastern horizon going from northeast to ...
  A: What you need is a good introductory astronomy (college) text which has a chapter on the celestial ...
is it Time travel happens near black hole and pyramid area?8/28/2010
  Q: is there is any relation between pyramid area, black hole and time travel? Regards, Dinesh
  A: Time travel is not feasible in any way, shape or form. That depicted, e.g. in movies, using black ...
gravity8/27/2010
  Q: How is it that gravity supposedly holds the 8 known planets in orbit around our sun when they are so ...
  A: It really is no problem at all! You can actually compute the magnitude of the force of gravitational ...
Theory of relativity & Time Dialation8/23/2010
  Q: I have read about the Time Dialation on the web. As I understood it says that if we move with the ...
  A: First, no one can move at the "speed of Light" - certainly no material object. The relativistic ...
Moon's speed without Sun8/17/2010
  Q: A website claimed that if Earth-Moon system were isolated from Sun's gravity, Moon's orbit around ...
  A: You don't cite a source or link for these calculations, but I have never seen anything like them ...
The Moon7/28/2010
  Q: I wanted to know what would have to be done to turn the moon into an interstellar comet? A ...
  A: Personally, I can't think of anything feasible OR desirable that we could do (or would wish to do) ...
angle of the sun7/27/2010
  Q: Can you tell me what the angle of the sun is at the equinoxes and solstices, for Palm Coast, FL ...
  A: You haven't specified altitude or azimuth but I am going to assume you mean the maximum altitude of ...
21 Aug 20177/24/2010
  Q: Seeing a total solar eclipse is in the top ten of my "bucket list," a list of things I'd love to do ...
  A: Wyoming is a beautiful place - my wife and I visited Jackson Hole, Cody and Yellowstone in 1998 and ...
Supernova-Solar System7/17/2010
  Q: I have some questions about the formation of our solar system. They say it’s the Nebular Hypothesis. ...
  A: Hello, Alas, this may be a tough one to solve. The problem is that the use of concepts such as ...
How to calculate the date of a solstice7/7/2010
  Q: I have an interest in archeo-Astronomy and I would like to calculate the date of an event in past ...
  A: Your question poses problems at several levels, but let's examine the major ones. First, there's ...
astronomy observations6/15/2010
  Q: Your question was without using telescopes or satellites what are the observations that early ...
  A: Okay, no need for snark. I had to ask because the question fit the profile of numeros others that ...
Hubble Discovery6/11/2010
  Q: I have a question about Hubble's discovery and the big bang theory. How does Hubble's discovery of ...
  A: One can think of the visible expansion of the universe, in terms of the recession of galaxy clusters ...
constellation4/26/2010
  Q: In which constellation do the Earth belong to?
  A: The assignment of constellations is based on a geocentric perspective. That means, they're ...
Neptune4/18/2010
  Q: What would happen or could of happened to life on earth had the planet neptune never existed in our ...
  A: I don't think anything would have happened. We'd just have a solar system with eight planets ...
How to calculate Doppler Shift?3/31/2010
  Q: In hydrogen, the transition from level 2 to level1 has a rest wavelength of 121.6 nm. suppose you ...
  A: The key here is to note the "rest wavelength" and the other values relative to it. Recall that in a ...
Fission star3/25/2010
  Q: Is it possible that someplace in the universe there exists a large celestial body made of ...
  A: Nuclear fission is an implausible means for stellar energy simply because of how stars originally ...
earth's elliptical orbit3/22/2010
  Q: i do mathematics in high school. and i have an understanding of conic sections and the formula for ...
  A: Yes, the Earth's orbit can be calculated- by obtaining what we call the orbital parameters. Let's ...
Radiation of Energy3/13/2010
  Q: The mass of the Sun is 1.99 x 10^30 kg. Every second, it radiates 3.8 x 1026 J of energy. (a) How ...
  A: The key here (actually, the luminosity is closer to 3.9 x 10^26 J/s) is using this figure in ...
Celestial mechanics question3/3/2010
  Q: Can you provide a way to show the perturbation of planets without getting overly technical? (This is ...
  A: I have pretty well summarized the approach to be used from the figure I’ve uploaded. The elements ...
Uranus rotation2/26/2010
  Q: I know Uranus is said to rotate on it's side (although how can they be sure it's on it's side rather ...
  A: You have lots of questions. I believe most are answered at the link below - a site by another ...
Astronomy2/22/2010
  Q: I am the guy that asked the question about measuring the temperatures on planets in our solar system ...
  A: Okay, that's fine. The general practical method is using what's called a thermocouple- which now, of ...
Spinning2/19/2010
  Q: Why do most, if not all, spacial objects like planets, moons, stars, suns, galaxies -- even meteors ...
  A: Well, I don't know that meteorites spin around any axes in any uniform way, but that's a topic for ...
pollution2/11/2010
  Q: What is the relation between the global warming and the ozone hole ?
  A: Basically, it was found that the predominant agents causing ozone depletion (the CFCs or ...
Fourier expansion of (w-M)2/8/2010
  Q: I am interested in satellites with highly elliptical orbits like the Molniya. In that case I would ...
  A: Actually it is the Lagrange expansion theorem which is used to generate terms for (w - M) which is ...
Gamma Rays and Atmosphere1/28/2010
  Q: I read and understand that high-energy, high-frequency gamma rays are very penetrating. How then ...
  A: This is actually not the serious problem many believe, the primary reason being that any gamma rays ...
star1/26/2010
  Q: What is the first sunlike star to possess a planet?
  A: The first discovery of a sunlike star to have a planet was probably the G-type star 51 Pegasi, which ...
Research1/25/2010
  Q: Mr. Stahl The movie 2012 was released last year. I have recently read numerous article on sunspots ...
  A: There has been so much babble written concerning solar cycle 24 (the alleged "missing cycle") that ...
astronomy1/24/2010
  Q: what is the proper clothing and other precations for safely making observations at night and in cold ...
  A: This will basically depend on the location - and in particular - how cold it is! In addition, not ...
Astronomy1/23/2010
  Q: Mr. Stahl Thank you for clarifying the previous question regarding the sun. I never understood the ...
  A: Unfortunately, your needs here require a comprehensive approach and more detail than can be ...
Sun1/22/2010
  Q: Mr. Stahl While reading an article on the sun I noted that it is composed of six "core" parts with ...
  A: I think you already discovered (yourself) at least one way- since you identified communication ...
aurora borealis1/18/2010
  Q: A student of mine asked the following question... "If a person were standing at the North magnetic ...
  A: No, one wouldn't see the entire "ring" - which goes by the name "auroral oval" (and extends from ...
Gamma Ray Burst1/12/2010
  Q: Stahl, I'm curious about gamma ray bursts. Could one take us by surprise? That is, say one occuring ...
  A: There have been some fear mongering articles-pieces about these GRBs, but none of them have been ...
Astronomy11/30/2009
  Q: Good afternoon Sir I am attempting to decipher the following: Discuss stellar magnitude. What are ...
  A: Basically you are "on the right track" but I'd quantify the magnitude definition a bit more. For ...
Spiral Galaxies11/30/2009
  Q: The stars in the inner part of a galaxy move faster than the density wave/s and the stars in the ...
  A: First, it is well to bear in mind that the particular density model will vary depending on the ...
expansion of universe11/23/2009
  Q: Phillip, for that detailed answer! I will peruse it in depth, when I get more time, later today. ...
  A: No, there is no chance molecules are expanding either. Again, if it were the case, then molecular ...
Barred Spirals11/23/2009
  Q: Forgive me for belaboring the subject of bars in spirals, but I was wondering that if, as you said ...
  A: The short answer here is "not really" because - as I noted in an earlier response, this again ...
expansion of universe11/21/2009
  Q: My question is this: Assuming that the distance from the center of any 2 objects O is 1X, and the ...
  A: Based on your example, it is impossible for the distance ("0.8X") between two objects to remain the ...
Crystalline patterns in meteorites11/19/2009
  Q: A few years ago I heard something on a TV program about meteorites that has been bugging me and I ...
  A: Sorry, but I have heard of no such phenomenon. Nor am I aware of any such properties attributed to ...
Hyper Novas & Galaxies Black Holes11/10/2009
  Q: I'm a young astrologist and I know about super novas. On google i have seen hyper novas, and I'm ...
  A: First of all, there's no such thing as an "astrologist'. You have astrologers, and astronomers - but ...
Neutron star formation with different forces11/9/2009
  Q: Would it be possible that a collapsing star directly become a neutron star without lightening up if ...
  A: Alas, if the changes noted by you were in effect, it would be doubtful there'd be any stars at all. ...
Kepler’s Law of Periods11/7/2009
  Q: Can you please show me step by step how to use Kepler’s Law of Periods to find the period of the ...
  A: Actually - the mass of the Sun is 1.99 x 10^30 kg Anyway, we begin by setting the gravitational ...
Solar flares/UV radiation11/2/2009
  Q: Is it possible for solar flares or some other solar activity to bombard Earth with increased UV ...
  A: Unfortunately, there are few genuine scenarios for such an event unless the flare was absolutely ...
Astronomy and "global warming"10/23/2009
  Q: Is "global warming" affecting the amateur astronomer? Do you have any images from the past to ...
  A: I am really not sure what you mean by global warming "affecting the amateur astronomer". Do you mean ...
Anomaly...10/17/2009
  Q: Is there any public evidence(study,record)to support the continuing theory that there may be another ...
  A: The "Nibiru" stuff is all basically claptrap. At a Meeting of the AAS Dynamical Astronomy Division I ...
geometry of the cosmos9/27/2009
  Q: Where is cosmology now on the overall shape of the universe? Is it a big sphere, with the galaxies ...
  A: Rather than trying to deal with this textually, I think you will find most of your answeres ...
36hrs of day9/24/2009
  Q: Is it is correct that on 17th oct 2009 continuous 36hrs of day in eastern countries & 36hrs of night ...
  A: The Earth rotates at a relatively fixed rate, yielding a total time for each daily rotation about ...
Moon observations: NASA's planned explosion9/21/2009
  Q: NASA is planning to drop a bomb on the moon on October 9th 2009 to try and detect water in the ...
  A: It actually isn't a literal "bomb" being dropped but rather an impact created from a craft- device, ...
Light Years Between planets9/21/2009
  Q: How many light years would it take to get to venus(from earth)? venus to mercury? mercury to ...
  A: Actually, the distances in the solar system are more suitably measured or noted in "light minutes"- ...
star death and big bang phenomenon9/16/2009
  Q: . so based on that learning how do scientist predict that big bang is the beginning of the universe ...
  A: Basically, the answer to the first question is a matter of degrees....in temperature! While the ...
black holes9/8/2009
  Q: I've read that the laws of physics break down in a black hole, but specifically, what laws? It ...
  A: The issue at hand is where, which regions of the black hole are subjected to examination of natural ...
end of the world9/6/2009
  Q: iv read so many things on the Mayan Prophecy and it said that the planets will alighn with the ...
  A: Aaaaargh! This again! All over the net, it sometimes seems people are going bonkers worrying about ...
physics9/5/2009
  Q: what is the escape velocity of a space ship from earth going to outer space? and what is the ...
  A: Technically speaking, there is no single escape velocity, since it will differ according to the ...
Black Spheres9/3/2009
  Q: Why do we call Black Holes... "Black Holes?" Don't they exist in three dimensions. Wouldn't it be ...
  A: I think that the unfortunate belief that black holes are "spheres" got started with one of Stephen ...
Big Bang8/28/2009
  Q: If all the universe is expanding, as if we're on the surface of a bubble, then why is there an ...
  A: First of all, the observational fact of the cosmos' expansion is not in any way conjoined with being ...
CMB8/18/2009
  Q: I am Steffi Michael, Cosmic microwave background radiation{CMB} is a topic important & in relation ...
  A: First let's deal with the last part, concerning the energy associated with supernovae. This was ...
astrophysical fluid dynamics8/18/2009
  Q: Pls give me a brief explanation about the astrophysical fluid dynamics. Nalaka
  A: Very basically, astrophysical fluid dynamics entails the application of the principles of fluid ...
origin of planet earth8/14/2009
  Q: I heard something within the last year, probably on NPR, regarding the origin of our planet and the ...
  A: The assertion that the Earth is somehow unique and couldn't survive "bombardment" by other bodies ...
Barred Spirals8/13/2009
  Q: Please tell me what is known about the causes of bars in some spiral galaxies. Also, it is hard to ...
  A: Again, the "causes" of bars, e.g. in barred spirals, is still up in the air, although some theories ...
Something I saw during the meteor shower8/12/2009
  Q: Last night at roughly 10:45 pm My family and I were out watching the meteor shower. While watching ...
  A: Unfortunately, without a lot more information, it simply isn't possible to provide an unambiguous ...
worm hole8/11/2009
  Q: What is meant by worm hole and how it will form?
  A: A worm hole is thus far a totally hypothetical construct which has been hypothesized, but never ...
Stellar Parallax8/10/2009
  Q: I am looking for a simple explanation of calculating the distance of a star using stellar parallax. ...
  A: Unfortunately, there is no 'simple means' I am aware of to actually *calculate* ( as opposed to ...
a special orbit of earch8/3/2009
  Q: Is it possible to create an entery into earth's atomosphere in such a way that the object just falls ...
  A: No such re-entry is possible, because of the density of the atmosphere. One would be literally ...
Gravitational Relaxation7/13/2009
  Q: I was reading about galaxies in Wikipedia. In the section entitled "Future trends" towards the ...
  A: Generally, in reference to astrodynamic systems, when one refers to "gravitational relaxation" s/he ...
barred spirals7/11/2009
  Q: I have been looking around the net as to why bars in spiral galaxies occur and see conflicting ...
  A: Unfortunately, I can't tell you very much at a deep level, which is the level at which you appear to ...
spinning galaxies7/8/2009
  Q: I would like to know how many years it takes for other galaxies, large and small, to make one ...
  A: First, there are many other types of galaxies, including elliptic, colliding, spiral etc. so one ...
Solar Output and Climate Change7/3/2009
  Q: I have recently been having a debate with co-workers about the issue of climate change. My ...
  A: You are correct that the claim of a warmer Sun has been discredited. Having just returned from the ...
I would like an opinion on my theory.6/30/2009
  Q: What is the probability that the other end (opposite)of a black hole is the culmination of a new big ...
  A: Your take is actually pretty similar to an early version of "white hole" speculation, made famous in ...
Black Hole Cataclysm?6/2/2009
  Q: I am a 10th grade student so this may seem a biit out of my leauge but... give me a chance. I am ...
  A: I think you have some misconceptions - mainly concerning the physics issues, in your questions. ...
sun5/30/2009
  Q: how cold would it get on earth if the sun went away
  A: If the Sun "went away" the temperature would drop to near absolute zero (-273C) within 8- 15 mins. ...
Suns5/24/2009
  Q: I am particularly interested in studying The Sun at University, after having completed Engineering. ...
  A: What I would suggest you do before considering a university program, is getting hold of the book ...
Moon Path5/17/2009
  Q: I live in the western part of New York State and I was wondering what time of year the moon's path ...
  A: ASTRONOMY magazine has excellent foldout maps which can show the path of the Moon through any given ...
Bands on largest planets5/11/2009
  Q: I was wondering why there are clear bands of different colored clouds on Jupiter and Saturn instead ...
  A: The standard view on the cloud bands for Jupiter, Saturn are that they arise from convective ...
A-class stars5/6/2009
  Q: Can you give me some info about A-Class Stars?
  A: Spectral A-class stars are blue-white in color and exhibit surface temperatures of: 7500 - 11,000 K. ...
Astronomy5/5/2009
  Q: I just had some astronomy questions I was wondering if you could clarify: I know that the dominant ...
  A: The specific sequence for the p-p chain fusion is as follows: 1) e(-) + H1 + H1 -> D2 ...
Moon Path4/30/2009
  Q: Is there a time of year or month when the moon and sun follow close to the same path in the sky? ...
  A: I am aware of no specific time of year where the Moon and Sun follow the same path in the sky, other ...
fabric of space and time4/30/2009
  Q: Einstain said on his theory of relativity that earth wrap the fabric of space and time to create the ...
  A: Actually, you are confusing the general theory of relativity with something else. The general theory ...
Viewing4/28/2009
  Q: I just finished reading this article at ...
  A: What you are forgetting is that the expansion of space and time commenced with the Big Bang. The 630 ...
space4/24/2009
  Q: if we could look into space and see the past, whats stopping us from looking into the future from ...
  A: First, the "past" we see is simply derived from extra-galactic (distant galaxy clusters, quasars) or ...
Lunar Eclipse4/13/2009
  Q: Can a Lunar Eclipse occur during a New Moon?
  A: NO - it cannot. A lunar eclipse (eclipse of the Moon) occurs when the Earth's shadow falls on the ...
Solar Image4/12/2009
  Q: I am a amature astronomist. While viewing the son in Feb. of this year, I keep seeing something I do ...
  A: It really isn't possible to say very much without knowing many more details of the observation. For ...
The variety of star size4/10/2009
  Q: I find it surprising that stars are so variable in size. I would have thought that as as gas and ...
  A: The key answer to your question resides in the *type* of nuclear fusion the star undergoes. For ...
GreenHouse gasses4/7/2009
  Q: Where do the green house trap its energy?
  A: Your question is somewhat unclear, so if my answer is not what you expected, you may have to revise ...
Force of Attraction3/29/2009
  Q: What is the force of attraction between the Sun and the Earth? I have the formula but I feel like ...
  A: If the result isn't coming out as you think it should, it may be that your units are inconsistent. ...
Interview3/18/2009
  Q: I am doing a project for school, and an inteview is required for it. My topic is climate change, do ...
  A: I have no objections to an interview but first I'd like to know the basis for it: HOW conducted, ...
shadow casting observations3/15/2009
  Q: Stahl My question was on which date, in latitude 13° 32' South, the tip of the noon shadow will be ...
  A: Your question-problem is actually not so simple as first appears because you do not ask for a ...
astronomy3/9/2009
  Q: In my 8th grade Earth Science class, we are looking at sunrise and sunset times. On March 17, the ...
  A: You ask a good question. It is true that the also implying "equal day") but as they say, the devil ...
Your Thoughts3/8/2009
  Q: I was hoping you could answer these questions as soon as possible. 1. What are your thoughts on the ...
  A: I believe I have given my thoughts on the Big Bang before, but in any case will summarize again: 1) ...
Angle of Moon (Laying on it's back)3/4/2009
  Q: I'm having trouble with what may be a simple answer. It seems to me that the illumnation angle of ...
  A: From your information I really don't think there is any "pole shift" to worry about. It's probably ...
Quarter moon3/3/2009
  Q: on February 26, 2009 approx 800pm CST the moon was in the shape of an upright crescent with a star ...
  A: These sort of close conjunctions of the Moon with a planet often occur. You just may not have seen ...
comets3/2/2009
  Q: I have got two questions concerning comets. I would like to know 1. how fast in general do comets ...
  A: The speed of a comet will depend on where it is in its orbit. It will always go much faster at ...
creation of universe2/28/2009
  Q: If God did not create the universe which many claim please explain the retrograde motion of Venus ...
  A: Whether the retrograde motion of Venus or the anti-polar axial tilt of Uranus can be "explained" or ...
Inaccessible question-flare stars2/26/2009
  Q: I have two questions, one directly related to astronomy and one related to a question you recently ...
  A: Absolutely I have no idea why the question cannot be brought up, but you are correct that when the ...
solar flairs2/26/2009
  Q: Why do solar flairs happen and how?
  A: No one is sure as to 'why' solar flares occur. As to how, we know that there are probably at least ...
satellites2/24/2009
  Q: Can you confuse stars and man made satellites? I thought you can see the lights on man made ...
  A: Having observed many satellites in my younger days (e.g. Echo I) I can tell you that it is ...
first law2/23/2009
  Q: I am an young earth creationist.My two questions are thus.Please explain how something can come from ...
  A: First, it is not technically possible to apply the first law of thermodynamics to the *inception* of ...
meteors2/20/2009
  Q: I was looking at two explanations as to why meteors burn as they go through the atmosphere. One says ...
  A: The key point is that "friction" does play a role in whatever case, but the particular form of ...
Meteor impacts on earth2/18/2009
  Q: I was wondering if you could please tell me if when a large meteor, such as the one that led to the ...
  A: Typically large asteroids such as the one that impacted 65 million years ago (and was possibly ...
expanding universe2/15/2009
  Q: Philip, According to current theory, what happens to the light traveling outward past the edge of ...
  A: Th notion of light "travelling past the edge of the universe" is a very tricky concept, especially ...
Geography2/9/2009
  Q: Who was the first person to model the earth as a sphere? Who made the first accurate measurement 0f ...
  A: I am trusting this is not a HW question, as I do not answer those. A good sign here is that you have ...
Western Sky2/9/2009
  Q: Last night, February 8, 2009, in the area of Venus a bright light appeared. Much brighter than ...
  A: In all likelihood, it was Venus, at magnitude (-4.6). It is now the second most brilliant object ...
The two tropics: Capricorn and Cancer1/31/2009
  Q: NASA has measured the exact timing when the earth would be closest to the sun, or farthest away from ...
  A: Plowing through your script, I think the bugbear in the works (and what seems to be troubling you) ...
Strage orange light phenomenon1/29/2009
  Q: I live in Windhoek, Namibia (22°35'41" S 17°05'36" E). On the night of Tuesday, 27 Jan 2009 at 21h09 ...
  A: Alas, without a detailed report (much more info than what you have provided) there is little that ...
Earth Flares1/25/2009
  Q: plasma sphere that i saw (http://en.allexperts.com/q/Astronomy-1360/2009/1/Earth-Flares-1.htm). I ...
  A: First some preliminaries: when I referred to "casual speculation" I meant basically you are ...
telescope1/20/2009
  Q: Dr. Stahl, Don't you think it would be worth while to put up another telescope in space that would ...
  A: It would definitely be worthwhile to put up another space telescope, but I myself would much prefer ...
Earth Flares1/18/2009
  Q: http://en.allexperts.com/q/Astronomy-1360/2009/1/Flare-activity-earth.htm and for the follow up you ...
  A: Actually, after giving your original question further thought, I am not convinced the phenomenon you ...
Astrophysics1/17/2009
  Q: I'm really interested in astronomy and i love the beauty of the skies and i've been teaching it to ...
  A: Unfortunately, astrophysics is not an easy subject! Nor is memorization adequate, since one must ...
Orange Light1/15/2009
  Q: We observed about 9pm this evening, in the uk, a bright orange light moving across the night sky. it ...
  A: From what you describe, it appears to be exactly what you first thought - a fireball. (Otherwise ...
Big Bang/Motion of the universe1/13/2009
  Q: I am very new to astronomy and would greatly appreciate your help with a question I have. I have ...
  A: All the evidence we currently have discloses the cosmos is being *pulled apart*, not in the "same ...
geography1/12/2009
  Q: One of my students asked me the following question? What caused the sun to become tilted at 7.25 ...
  A: Unfortunately, no one knows the answer to that. It likely occurred in the early stage of solar ...
REAL loss of daylight1/10/2009
  Q: Some time ago there was a ridiculous question about losing daylight you answered. What I want to ask ...
  A: Yes, unfortunately I remember that question. It has me now much more on the alert for nonsense (not ...
black holes and the sun1/8/2009
  Q: i am 17 years old and i was wondering is it possible that when a star dies and produces a black ...
  A: No, it isn't possible at all that such a scenario applies, because the black hole which is the ...
Electrical Universe1/4/2009
  Q: Dr. Stahl, I came across an interesting video on Google videos called "Thunderbolts of the Gods". ...
  A: I am familiar with the basic "electrical" (actually, plasma) universe proposal, as it has popped up ...
Extraterrestrials?12/23/2008
  Q: I have two questions I hope yhou don't think are too frivolous: 1) Is is possible that alien ...
  A: Actually, I paused when I saw the question header as I've been receiving a lot of "fringe" questions ...
Losing Daylight - Rush Limbaugh12/22/2008
  Q: Dr. Stahl, My question is why don't you verify what was said before commenting on it? See Rush ...
  A: Oooookay...I guess it's "gotcha" time again on this channel. First, let me say I pay no attention to ...
Losing daylight????12/20/2008
  Q: I too, heard Rush Limbaugh yesterday(12-19-08) 'verify' that we are losing daylight, because of some ...
  A: Of course, he probably never mentioned HOW he "verified" it. Which is key to the whole pile of ...
losing daylight/ worried12/19/2008
  Q: I first want to apologize because I am sure my questions is going to seem silly compared to most of ...
  A: How can I say this? In terms of astronomy, 'EL Rushbo' is an idiot. Why anyone would listen to him ...
Meteors and meteorites12/19/2008
  Q: Dr. Stahl, What would the difference in appearance be between an iron meteor that is still in its ...
  A: Almost certainly the meteorites that have gone through the atmosphere (assuming they are large ...
Asteroid protection & global cooling12/16/2008
  Q: I was reading through some recent answers and am somewhat confused. Do we have anything, any sort of ...
  A: The Reagan “SDI” (‘Strategic Defense Initiative’) wasn’t killed by any such critters as “liberal ...
Beyond the light horizon12/15/2008
  Q: I was watching something on TV that said that we can only see 13 Billion light years in either ...
  A: Actually, that is "see 13.7 billion light years in either direction". However, as noted in one ...
Seasons12/14/2008
  Q: If the Earth were to be at a tilt of zero degrees would the location of the tropic of cancer become ...
  A: THe 'Tropic of Cancer' is defined as is the northernmost latitude at which the Sun can appear ...
Astronomy (college)12/8/2008
  Q: This is for a project BUT WAIT!!!! I am in 9th grade and I am required to interview an expert with ...
  A: 1. Most astronomers are affiliated with colleges or universities. Therefore, their main activities ...
viewing distant galaxies12/8/2008
  Q: Don't want this to sound silly, but if we are viewing galaxies that light has just reached us, back ...
  A: First, the cosmos is not like some giant mirror. Merely because we are looking back in time (or at ...
einstein field equations12/3/2008
  Q: Mr. or Dr. Stahl, Can you direct me to where I might find FORTRAN or MAPLE code for analyzing some ...
  A: I am aware of no code such as those you reference which deals with the Einstein Field equations for ...
Axis shift and Global Warming12/2/2008
  Q: I've heard that the shifting of the Earth's axis can effect global climate. Can this process work ...
  A: This question (or rather one very similar to it) was actually answered some time ago. You can find ...
John Dobson11/28/2008
  Q: I was wondering if you have heard of John Dobson of the Sidewalk Astronomers, and if so, what do you ...
  A: Yes, I've heard of Dobson ("father" of the Dobsonian telescope) but whether he has taught anything ...
Weird flash11/18/2008
  Q: this has bugged me for ages. I'm a professional sailor and have spent many evenings in the middle of ...
  A: Given the absence of much more (specific) data it is virtually impossible to even speculate as to ...
moon11/17/2008
  Q: I would like to know if the people in the western hemisphere see the same moon to the people in the ...
  A: Your question is not entirely clear. You are asking how the Moon appears in the "western hemisphere" ...
on stars11/14/2008
  Q: I noticed that usually same 3 or 4 stars is always visible after sunset initially. Is that because ...
  A: It is probably more likely that these "3 or 4 stars" are brighter (have lower apparent magnitudes) ...
stars visibility11/11/2008
  Q: When we observe the sky after sunset, we see only 3 or 4 stars. As night arrives, we see more stars ...
  A: Relatively fewer stars are visible earlier in the evening because of astronomical twilight which can ...
climate change11/10/2008
  Q: Sir, Are you familiar with the studies being done at the Danish national space Center(institute) on ...
  A: Sorry - but I've seen no such studies referenced in any publication, nor have I heard of them. Can ...
stars and light11/10/2008
  Q: If some of the stars we see may have actually died long ago and it has taken that long for the light ...
  A: In answer to your first question, the time depends on how far away the star is - given that the ...
Comet-Like Knots Around a Dying Star in the Helix Nebula11/9/2008
  Q: Dr. Stahl, Please tell me what is involved in the formation of comet-like objects such as those ...
  A: First of all, any protostar -type object (including the early Sun) will spin off detritus in the ...
lunar mass and revolutions10/26/2008
  Q: if mass or weight is added to the moon,such as astronauts and/or moon bases, overtime will the added ...
  A: The mass of the Moon is ~ 7.5 x 10^22 kg. Even ten astronauts would not exceed 2000 kg, or a ...
bright object in sky10/22/2008
  Q: I live in San Marcos Texas. For the past few nights I've noticed this really bright object in the ...
  A: Well I checked for the time and location you gave and it isn't Venus. In that direction and time it ...
astronomy10/21/2008
  Q: How do visual telescopes show the temperature and luminosity of stars?
  A: Visual telescopes in and of themselves cannot show either the temperature or luminosity of stars. ...
dust in protoplanetary discs10/19/2008
  Q: What is the main chemical composition of dust particles in protoplanetary discs; are these particles ...
  A: First, the evolution of these proto-planetary disks is still not fully nailed down, so please ...
The earths orbit around the sun10/12/2008
  Q: How did ancient astronomers figure out it took 365 & 1/4 days to travel around the sun 1 year. ...
  A: Your question demonstrates it is possible to ask something that (apparently) is relatively simple - ...
Auroras10/11/2008
  Q: hello, a quick question on the physics of auroras please - i just wanted to confirm the following ...
  A: Elsa First, your general description is basically correct. There is just a little more detail that ...
......9/23/2008
  Q: help me out here...should i call up and warm my local congressman of the dangers? ...
  A: My answer? You should stop worrying about remote, distant and improbable catastrophes like ...
formation of a black hole9/23/2008
  Q: How a black hole is form.
  A: A black hole can be formed when the core of a massive star (greater than about four solar masses) ...
CERN9/20/2008
  Q: how worried if at all should we be about whats going on at CERN
  A: I believe I answered a question like this previously (well, anyway, it was a question bundled ...
....9/19/2008
  Q: Are Betelgeuse's poles aligned at us? And are any nearby gamma ray bursts going to hit us anytime ...
  A: I do not believe anyone knows anything about Betelgeuse's "poles" and whether aligned "at us" or ...
Complete Confusion9/18/2008
  Q: This question is probably easy for you but I am completely confused. Science isn't exactly the ...
  A: From what I can glean from your query, you are confusing two different things here: the universal ...
astronomy9/17/2008
  Q: Stahl, my question is related to doppler shifts with stars in our galaxy. Do stars in our galaxy ...
  A: Again, as I have asked others, I have to ask you if this is a homework question. If it is then you ...
universe age and size9/12/2008
  Q: It would seem that lately everybody is saying that the universe is 13.7 billion years old, but i ...
  A: First off, "everybody" is not asserting a specific age for the universe. The 13.7 billion figure is ...
dark matter9/12/2008
  Q: i am curious to know if dark matter is the shadow of something and lack of light creates density due ...
  A: Dark matter has nothing to do with the 'shadows' of anything. Your "theory" merely shows you lack a ...
lunar nodes9/12/2008
  Q: I would like to find a table or light freeware that gives the time and dates of the ascending node ...
  A: Well, I checked my own programs first ('Cybersky' and 'Astronomy Lab') and could only find the ...
CERN particle collider9/11/2008
  Q: it says on foxnews.com http://www.foxnews.com/story/0,2933,418204,00.html ...
  A: All this hype about yet another "cosmic catastrophe" (this time initiated by "careless" humans on ...
astronomy9/10/2008
  Q: my question deals with stars. Why are many of the stars nearest to Earth not visible to the naked ...
  A: You pose a good question. If one gets hold of the list of nearest stars, e.g. pp. 2-13 to 2-16 in ...
...9/9/2008
  Q: what do you make of this? http://www.petitionproject.org/ has the signatures of over 31000 ...
  A: I have seen this "thirty one thousand" petition in a number of places. Bottom line: 99% of the ...
education in astronomy9/3/2008
  Q: your answer was so helpful i have to ask another. what are the best colleges for astronomy? how ...
  A: The best college-university for astronomy is probably Harvard. However, the University of Hawaii ...
Days9/3/2008
  Q: What is the exact definition of a day? If a day is defined as a full spin of the earth on its ...
  A: You have way way too many questions, and I only allow one to be answered at one setting, time. (Else ...
astronomy9/2/2008
  Q: How does astronomy help with everyday life?
  A: Astronomy only has very marginal practical benefits as far as everyday life. For example, if you are ...
im confused9/1/2008
  Q: i swear i read somewhere that for in order a star to be a supernova candidate it has to be over 9 ...
  A: There is a good deal of confusion mainly because there is a good deal of uncertainty. However, 1.5 ...
Earth Environment8/23/2008
  Q: I live in Buffalo, Ny and we get a great range of weather conditions while other places like ...
  A: I will offer an answer from a more or less astronomical perspective, but you may also wish to ...
answer8/21/2008
  Q: I am the student of engineering but i intersted about the study of universe.My question is about ...
  A: The expansion of the universe (actually manifest in the outward recession of the galaxy CLUSTERS) ...
Lights in the Sky off of Holden Beach8/21/2008
  Q: On August 19 between 9:00PM and 10:00PM I saw some very strange lights in the southern sky off of ...
  A: Without your completion of an Anomalous Optical Phenomenon report form it is impossibe to say what ...
Orbits8/13/2008
  Q: Why does one sattlite obit the earth while another is in a stationary orbit?
  A: This is a common misconception. In fact, BOTH satellites orbit, it's just that one orbits at the ...
global warming8/7/2008
  Q: look im an open person i really don't know who to believe on this global warming issue. Al gore, a ...
  A: I suggest if you are seriously interested in global warming to consult any or all of the prior ...
starz8/1/2008
  Q: As to the previous answer, i thought you didn't care about ratings since you disabled them in your ...
  A: It wasn't that I didn' "care about ratings" - it was that there were too many people that didn't ...
space7/31/2008
  Q: okay i have 3 question for u mr. stahl 1) what's at the end of space? 2)-so a galaxy with high ...
  A: Okay first, I only answer ONE question not series questions. (Since I only get credit for answer one ...
Dark matter/energy7/15/2008
  Q: Is dark matter and energy in another enviroment?Like the oceans and things in it are in a different ...
  A: Fritz Zwicky in 1933 actually laid the original, observational basis for dark matter. His ...
galactic alignment7/14/2008
  Q: I have been reading up on galactic alignment recently and can't seem to find much objective, ...
  A: I believe I answered this before in some form, so you may wish to check the past questions and ...
wr 1047/14/2008
  Q: i was wondering; since you seem very knowledgeable. -what's your opinion of stars such as WR 10 and ...
  A: At 8500 light years, Eta Carinae is a good distance away and the inverse square law for radiation ...
Gravitational Pull, Sun Angle's during Solstices, and Orbits7/14/2008
  Q: i am trying to do a review for a test on tuesday.... i cannot figure out the answers to 4 questions ...
  A: My concern here is that first: you are sending this to me barely a day before your test (which puts ...
Times effect on luminosity7/12/2008
  Q: The distance between the earth and the sun remains the same and the amount of light the sun emits ...
  A: The insolation (rate of solar radiation received on Earth in Watts per square meter per second) will ...
Your question about earth axis' shift and climate change7/10/2008
  Q: "Question I live in Milwaukee,WI. It's January and the temps have been around 40-50 degrees ...
  A: Earth's axial tilt has nothing to do with the current global warming acceleration, which is entirely ...
Physcial Science7/10/2008
  Q: Why do astronauts in orbit around earth see a black sky with stars that do not twinkle but see a ...
  A: Blue sky is caused by sunlight selectively scattered by the atmosphere, and in space there is no ...
Ik pegasi discussion (round 2)7/4/2008
  Q: if a type Ia supernova, at the distance of 1000 pc, dumps as much gamma-ray radiation onto the earth ...
  A: How many rounds are we going to go with this? Anyway, it seems you have misconstrued the answer to ...
southern cross6/30/2008
  Q: Can the southern cross conselation be seen from the island of Maui????
  A: Maui is at latitude 20 deg 48 min North. This means any objects with a declination of 20o 48' would ...
Astronomy6/26/2008
  Q: Since the job prospects in the Astronomy field are not that great, what are the chances of becoming ...
  A: I see that you read the other previous answer I gave on this issue. The good news is that you at ...
Job Prospects6/25/2008
  Q: I want to become an astronomer. I have a Biology bachelor's degree, but I am willing to get a degree ...
  A: Unfortunately, the job prospects in astronomy are not that good. Most of this can be blamed on ...
IK Pegasi (HR 8210)6/22/2008
  Q: As you know IK Pegasi is a binary star system that's 150 lightyears away from earth that has the ...
  A: First, in the context of supernovae (Type 1a or other) the levels of uncertainty are such that no ...
universe6/20/2008
  Q: I have a few questions .The super Collier CERN ,are we trying to detect the big bang and if so ...
  A: First of all, it is quite impossible for CERN or indeed any super-collider to replicate the big ...
Earth's orbital period6/15/2008
  Q: How has the Earth's orbital period changed over time? I assumed it has changed due to the Sun losing ...
  A: The answer here is a minscule amount, so minsucule it would be totally unnoticeable over human ...
Telescopes!!!6/10/2008
  Q: I want to buy a telescope, however I am a complete beginner. I always had an interest in space and ...
  A: The biggest mistake that most beginners make is buying too much telescope. They then end up with an ...
The moon6/6/2008
  Q: Im in year 10 and currently doing a project on the full moon and need to know if its only in the sky ...
  A: Technically, the phase known as "full Moon" occurs specifically for a particular alignment of Sun, ...
Stellar Brightness6/5/2008
  Q: .. To compute the "brightness" of a star the formula is -- B = L / 4*PI*D^2 "L" I think is ...
  A: I agree what you have here looks whacky. But then there is no context, so it cannot be checked. Is ...
Earth's equator vs ecliptic plane6/3/2008
  Q: Philip: If the earth was not tilted, would the daylight period on the earth be the same year round? ...
  A: If Earth was not tilted, then effectively there'd be no ecliptic. Or, to put it another way, the ...
The Sun and Black Holes.5/27/2008
  Q: Why is it impossible for the sun to turn into a black hole?
  A: Theoretically, any object of any mass can be transformed into a black hole IF forces can be found to ...
Hallo around Sun5/27/2008
  Q: I live in Central CA and today at 2:00 pm the Sun has a colorful halo around it. It looks like a ...
  A: How large would you say the angular dimension (radius) of the halo was? About 20-22 degrees? ...
Moon in the center of a perfect round hole in the completely cloudy sky5/22/2008
  Q: Hallo Philip, I am asking this question after an exhausting searched through the web. I saw a ...
  A: Again, the only explanation I can come up with is a 22 degree lunar halo phenomenon, along the lines ...
polar shift5/14/2008
  Q: There is much activity flying about 2012 alignment and other astronomical events occurring that ...
  A: Given my experience with a previous "alignment" (The "Jupiter Effect" in 1982) I am not convinced ...
Global warming5/12/2008
  Q: I am really really confused and hope you can help. In reading over past answers you've given on the ...
  A: Your confusion is quite understandable, and this happens whenever scientific issues are clouded over ...
Charts4/18/2008
  Q: We are going on holiday here in the uk from May 10th to 17th in Dymchurch on the south coast. The ...
  A: Unfortunately, I am aware of no site where one can simply print out a star chart for a selected ...
Star Gazing & Time4/13/2008
  Q: A friend recently told me that a star that a star that I might look at tonight might no longer be in ...
  A: First, I don't think there's any such thing as a "foolish question". What happens is that not all of ...
Life in certain solar systems4/6/2008
  Q: Most scientists' speculation re life on other planets is, IMO, too anthropocentric, in that they ...
  A: Geoff I don't think it's so much a case of being "anthropocentric" as "carbon-centric". In other ...
Solar flares3/28/2008
  Q: When looking at the sun, what quadrant would an eruption have the greatest chance of affecting the ...
  A: In going through my past papers, I only found two studies - both by Russians - that attempted to ...
Jobs in Astonomy fields with an Associates in Science (Astronomy)3/20/2008
  Q: I am 32 yrs old in the Chicago land area working in the printing field doing prepress/desktop ...
  A: and thanks for your inquiry! First, it is very difficult right now in the whole field of astronomy, ...
career prospects for fresh mechanical engineerin graduates in astronomy3/17/2008
  Q: i am in my second year of mechanical engineerin in india.i wanted to know the various career ...
  A: Unfortunately, I cannot see any career prospects in astronomy for anyone with a mechanical ...
Gamma Ray Bursts and the Sun3/14/2008
  Q: Phillip, I've been reading a bit on Gamma Ray Bursts, and my question is this: Assuming a short GRB ...
  A: Don't forget that the Sun is also a source of gamma rays - and also gamma ray bursts - especially ...
tides at Solstices3/4/2008
  Q: I'm not sure you're the right person to ask, but here goes: Why are tides so low at the soltices? ...
  A: Actually it isn't plausible that the tides would be highest or lowest at the solstices (unless we ...
moon distance from the earth2/22/2008
  Q: Is the moon at night closer to the earth at the equator than in California USA? Would one see an ...
  A: The answer to your questions are 'no' and 'no'. No, the moon is not closer to the Earth at the ...
clouds on venus and saturn2/19/2008
  Q: why does venus have clouds? what are the clouds made of? have astronauts bin to saturn and venus
  A: The clouds on Venus were probably formed soon after the planet itself. Some surmise, however, that ...
How stars are formed2/17/2008
  Q: How do stars form in clusters or binary when the solar winds from the stars that were formed first ...
  A: First of all, the Moon has no atmosphere because it lacks sufficient gravity to retain one. We know ...
Comet coming in 2017?1/31/2008
  Q: i have heard that in 2017 a comet is supposed to come to earth and kill us. Is this true or is this ...
  A: I haven't heard anything about any such comet. I am aware that an *asteroid* is supposed to make a ...
science1/17/2008
  Q: evidence that the earth revolves around the sun?
  A: Perhaps the best evidence for Earth revolving around the Sun, is the changing *apparent* position of ...
Star colors vs red/blue shift1/15/2008
  Q: If red stars are cooler and blue stars are hotter, how can we tell which stars are approaching, and ...
  A: Neither the color of stars (or their temperature) has anything to do with red or blue shifts. These ...
Space Phenomenon1/14/2008
  Q: Tonight me and two of my friends were stargazing and saw about 5 shooting stars scattered across the ...
  A: All I can do here is recount a similar experience my wife and I had in Barbados - while observing ...
mars1/13/2008
  Q: why doesn,t nasa set off a nuclear bomb on mars to heat the planet up so maybe some day to ...
  A: Setting off a nuclear bomb on Mars - say a 10 MT bomb- would accomplish nothing other than render ...
Career in Astro Physics1/11/2008
  Q: I'm a student in India who has great interest for physics and im good at math too... I really ...
  A: I have no idea of what the astrophysics (or other) requirements are for Indian post-secondary ...
Sunsets1/8/2008
  Q: As we were sitting at work this afternoon, we watched the sunset. Why does it look like the sun ...
  A: At sunrise and sunset, the Sun's rays (light) must travel through much thicker layers of the ...
Theoretical experiment12/18/2007
  Q: First of all, I realise AllExperts doesn't provide help with projects or homework questions (I'm an ...
  A: First of all, you are jumping the gun and “putting the cart before the horse” in your proposal that ...
Dont' all galaxies exhibit red and blue shift?11/21/2007
  Q: If a galaxy is rotating (say around black hole) don't stars one edge of the galactic plane have ...
  A: I think two different versions of red and blue shift are being confused here. Yes, IF one is ...
How are orbits formed?11/18/2007
  Q: I have always been so much interested to know so much about the universe, infact all about the ...
  A: Regarding questions (1) and (2) orbiting bodies (whether Moon about Earth, or Earth about Sun) do ...
Radio Telescopes11/9/2007
  Q: How have Radio telescopes developed since they were first invented?
  A: What you are really asking in your question, is for the history of radio astronomy. Of course, this ...
planets in orbit11/4/2007
  Q: If certain planets were to suddenly disappear from our solar system, would earth or its moon be ...
  A: The only conceivable effects would be gravitational in origin. That is, possible disturbance of the ...
Comets10/29/2007
  Q: Stahl, We are Mr. Sylvestre's 7th grade science class from Gallagher Middle School. We are doing ...
  A: First, it is not true that there is "no water in space". In fact, dozens of interstellar molecules ...
Gravitation10/22/2007
  Q: Need few clarification about gravity. If we assume to be in a freely falling elevator, we experience ...
  A: Your questions are as follows: i) Is the gravity a result of accelaration? The gravity experienced ...
Supernovas10/20/2007
  Q: How close would a supernova have to be to Earth to kill people? How close would it have to be to ...
  A: Both Type I and Type II supernovas can occur, and the Type II have strong hydrogen spectral lines ...
Sun and Moon Phases10/16/2007
  Q: Do the moon phases have any effect on the time of the sunset?
  A: NO, lunar phases have no effect on the time of sunset. This is determined by the obliquity of the ...
bullets10/14/2007
  Q: if you shot a bullet at the sun how long would it take to get there
  A: Actually, it would NEVER get there! The reason is that a bullet cannot be fired with a large enough ...
Moon10/2/2007
  Q: Why, at certain times does the moon appear to be larger than other times? Does it have anything to ...
  A: When an astronomical object is on the horizon at rising or setting, the numerical value of the ...
Earth' revolving9/24/2007
  Q: What would happen if the Earth stopped revolving around the sun and how would it effect the veiw of ...
  A: If Earth stopped revolving around the Sun, it would mean that its centripetal force (driving its ...
astronomy9/20/2007
  Q: where does the name constellatiions come from
  A: "Constellation" comes from the Latin, *constellatus* (con- stella-tus) Con = coming together, ...
dinasour extinction9/9/2007
  Q: I read the following in Science: At approximately 170 kilometers in diameter and having ...
  A: The key point to bear in mind in terms of the asteroids in the "asteroid belt" - is that they all ...
Astronomy9/6/2007
  Q: What would our seasons be like if earth were tipped 35 degrees instesd of 23.5 degrees? what would ...
  A: Sorry, but my computer locked twice and wouldn't let me copy and paste the answer, then the 'All ...
rotation of the earth8/30/2007
  Q: As long as I have loved watching the stars at night and staying up for hours watching the many ...
  A: The problem for a human trying to detect the Earth's rotation, is that he must use extremely clever ...
Cloud ring surounding moon8/29/2007
  Q: today , the full-moon day , I am seeing a strange phenomenon , the moon is full and cloud is ...
  A: You do not state the date or time of the observation, but given we are within 48 hrs. of a major ...
Climate Change Via The Sun8/25/2007
  Q: Climate-chnage skeptics point to the Sun to prove that it has more to do with climate-change than ...
  A: I’ve often been asked about a solar warming-global warming connection. I've always responded that no ...
calculating location of the moon, top of a mountian and my home town.8/10/2007
  Q: A few times a year, the moon will rise behind Mt. Baker (WA) USA, and it looks incredible from the ...
  A: Calculating the Moon's position for a given latitude and longitude is an *extremely* complicated ...
Astroarchaeology8/3/2007
  Q: Is it possible to find a lat/long on earth on a specific historical date given the Az and El of the ...
  A: The problem is that what you seek to find (longitude and latitude on a given date, for a given time ...
Star vs. Planet7/19/2007
  Q: My cousin asserts that all stars are planets. I say he is incorrect. Who is correct? Thank you, ...
  A: Alas, your cousin needs to improve his basic understanding of astronomy. Stars and planets are ...
Black holes7/9/2007
  Q: If nothing escapes a black hole because of the extreme gravity, why do x-rays escape?
  A: Actually x-rays do not "escape" the black hole proper. In most cases, holes are collapsed companions ...
Bright Light in Western Sky7/7/2007
  Q: I live in Dayton, OH and recently I've noticed a very bright white light (looks like a star yet is ...
  A: Looks to me like you are referencing the planet Venus, which dominates the western sky in the ...
accessible astronomy7/3/2007
  Q: I'm wondering if you can name some great books on astronomy (or cosmology) for non-astronomists. ...
  A: In your question you've posed an intriguing conundrum since most of the "great" books on astronomy I ...
Scientific plasuibility of an SF book6/25/2007
  Q: In a science-fiction book I've just read, by Poul Anderson("Ensign Flandry"), there was a mention ...
  A: You don't provide the date (year) the book was written, but I'd warrant it was probably before the ...
moon color5/20/2007
  Q: What color is the moon? Do you know of a book or website to support your answer?
  A: The Moon is not monochromatic, or "one color" - rather it displays different shades of color ...
Astronomy5/20/2007
  Q: In which two positions of the moon would Earth experience neap tides? In which would it experience ...
  A: The Earth experiences spring tides when it is aligned with Moon and Sun in a direct line. Thus, the ...
Galaxies5/13/2007
  Q: How did galaxies end up shaped differently? What are the differences, besides the shape, in ...
  A: Right now it isn't possible to say with any certainty how the differing shapes of galaxies arose. It ...
Stars in the sky5/7/2007
  Q: Are all the stars that we see at night just like our sun? Is it possible that planets could be ...
  A: In fact, most of the stars visible at night are *not* like our Sun. Many are Red Giants (e.g. ...
astronomy5/3/2007
  Q: (1)How was it possible that all matter in our present universe was compressed into a golf ball size? ...
  A: First, we've no way of knowing that - in fact, the present universe was compressed to "golf ball ...
astronomy4/25/2007
  Q: We see only one side of the moon because?
  A: The Moon rotates on its axis once every 27.3 days - which is *exactly* the same time period to make ...
Habitable Planet?4/25/2007
  Q: There's a new habitable, relatively Earth-like planet mentioned in Yahoo news:- ...
  A: The home star Gliese 581 is designated as a "red dwarf" which means much cooler and less luminous ...
life4/22/2007
  Q: Do you believe there is life on other planets? Also if you in 8th grade what debate would you do on ...
  A: In answer to your first question, yes, I do think life exists on other planets. Statistically, it is ...
heliosheath4/11/2007
  Q: i just heard about the heliosheath. i have two questions if you will, (not very easy ones, i fear) ...
  A: In theory at least, we have probably known about the heliosheath since the first advances made in ...
STAR4/10/2007
  Q: THERE IS A STAR BEHIND MY HOUSE THAT ALWAYS FLASHES DIFFERENT COLOURS SUCH AS GREEN,BLUE ANND YELLOW ...
  A: It is not possible to identify your "star" unless one knows what direction you were looking, and ...
question4/8/2007
  Q: is it right that in future our moon will become a planet
  A: In answer to your question, it appears the Moon may become a separate planet at a far distant date, ...
Scientific credibility4/7/2007
  Q: In the movie Sunshine, various astronauts are to deliver a payload of nuclear weaponry the size of ...
  A: My view is that the premise is palpable nonsense, especially given that the Sun loses an estimated ...
Planetary distances4/5/2007
  Q: Is there an online facility for finding out current distances of solar system planets from Earth? ...
  A: Unfortunately, I know of no sites that provide day-to-day updates of current distances of the ...
Solar wind and planetary atmospheres4/5/2007
  Q: I keep on reading comments by scientists that state that the reason why the Earth hasn't had its ...
  A: You are correct that it seems counter-intuitive. However, the difference is that Venus has an ...
global warming solar radiance4/5/2007
  Q: I have been interested in the effects of variations of the suns radiance ever since I heard of gm ...
  A: Unfortunately, when politics get injected into science everything suffers and reliable sources ...
Space4/4/2007
  Q: What is the distance in space measured in and its abbreviations ?
  A: The standard unit of distance used in astronomy is the parsec (derived from "parallax-second"). 1 ...
Solar flares4/1/2007
  Q: There are a few science-fiction stories which describe unusual massive solar flares which reach out ...
  A: The magnitude of solar flare described in the stories you reference is probably on a par with the ...
Star Sizes?3/28/2007
  Q: We are doing a project on stars.......we have been given a list of roughly 25 words related to stars ...
  A: Measuring stellar diameters is by no means an exact science, nor is it easy. It entails a lot of ...
Help!!!!!3/24/2007
  Q: I am very new at this whole thing but also very interested in it at the same time. The problem is ...
  A: Astronomy is a fascinating field, but it often takes a lot of effort, work to get into the use of ...
asteroid2/19/2007
  Q: Mr. Stahl- I have recently been hearing about this asteroid called Apophis which I understand has a ...
  A: At about 400 meters diameter, the asteroid Apophis - if it struck Earth- would carry roughly the ...
How complicated is the sun?2/14/2007
  Q: How many different types of activity are occuing in the sun? How long does it take the energy from ...
  A: There are probably hundreds of different physical, chemical processes occuring in the Sun - at ...
Measuring Masses1/22/2007
  Q: I've really tried solving all of these question but I am really have problem solving them so can you ...
  A: This is a follow -up. It turns out that you can actually obtain the Earth's mass very nearly exactly ...
saturn1/19/2007
  Q: i'm doing research for a magazine article about saturn. could you tell me about the makeup of the ...
  A: Saturn's rings are made up mostly of ice particles, tens of billions of them varying in scale from ...
earths axis/global warming1/10/2007
  Q: I live in Milwaukee,WI. It's January and the temps have been around 40-50 degrees fareneheit. I can ...
  A: There is absolutely no evidence that the tilt of the Earth's axis plays any significant role in ...
What did I see???1/8/2007
  Q: I witnessed something which has puzzled me for many years. Now that we have the internet, I ...
  A: It is doubtful that what you saw was a supernova. Like novae (exploding stars, but not quite so ...
Solar Flare & Northern Lights of 18591/5/2007
  Q: From what I understand, in this year the most intense display in recorded history occured. I read ...
  A: In 1859, Carrington and Hodgson independently observed a brightening of an area on the Sun in the ...
astronomy1/2/2007
  Q: For the last couple of evenings as the sun sets I've noticed a bright star South of the sun. I live ...
  A: You do not give the color or relative brightness of the object, but from the computer data I've ...
physics of solar flares12/14/2006
  Q: How does physics and solar flares mix? In other words why do you need physics to study solar flares? ...
  A: We need physics to study and analyze solar flares because the flare itself is a complex physical ...
sunrise12/12/2006
  Q: at the equator does the sunrise directly east
  A: First, let's set the reference bearing on the horizon. Imagine a circle of 360 degrees, and mark off ...
Search on extraterrestrial intelligence12/4/2006
  Q: I would like to know how much money should be spent on searching extraterrestrial intelligence? ...
  A: Mimi In answer to your question, I would say a minimal proper amount of money would be from $5- 10 ...
Distance and Size of Stars11/30/2006
  Q: As I am still working on my understanding of Astronomy I wanted to ask what proof do we have of the ...
  A: Fred The comprehensive answer to your questions involves a lot more math and physics than can ...
Movement of the Sun11/28/2006
  Q: Is the Sun, our sun, moving through space and, if so, what observable, demonstrable evidence do we ...
  A: Offhand I will bet when you asked this question you thought it might have a simple and ...
Space11/28/2006
  Q: how does sound waves travel in space doesn't it need air in order to travel. How can waves travel in ...
  A: Sound waves cannot travel in space under ordinary conditions, because they require a very high ...
Earth's movement11/25/2006
  Q: If everything in the universe is moving and there is no fixed point of reference, if we can detect ...
  A: What you are really getting at when you ask about some "universal motion" or speed (or absence ...
TOPIC: Sun & Current Events11/18/2006
  Q: I was pondering about how many years it would take for the sun to burn out? Furthermore, ...
  A: It will take approximately 6 billion years for the Sun to "burn out" - by which we mean all nuclear ...
Moonrise and moonsets10/29/2006
  Q: I am working on a moon project for my Geoscience class in college. I am really stuck with this ...
  A: Bear in mind the Moon's orbit around the Earth. Specifically, both revolve about a common center of ...
Sun and Moon Azimuth and Elevation, by location10/20/2006
  Q: Mr. Stahl, I am trying to find and application, or website, that will proivde sun and moon azimuth ...
  A: There are two (software) apps I know of that will probably address these issues. They are: ...
questions about finding Jupiter's Mass10/20/2006
  Q: I am studying for an astronomy test that is in a day and a half and am having difficulty with one of ...
  A: In this problem you are basically using Kepler's 3rd or 'harmonic law' to obtain Jupiter's mass from ...
universal law of gravitation10/18/2006
  Q: I dont understand the law of gravitation. can you explain? also I heard that quadrupling a distance ...
  A: Newton's law of universal gravitation asserts that every body or particle in the universe attracts ...
asteroid near miss10/13/2006
  Q: i was wondering what would be the likely effects of a large asteroid passing very close to earth, ...
  A: I would say no large asteroid would be able to destroy the Earth merely by virtue of a near pass or ...
Sun10/1/2006
  Q: I was wondering what the sun circles around & this isn't homework (I have been out of school for a ...
  A: The Sun (as well as the solar system) orbits the central massive core of the Milky Way galaxy. The ...
iridium9/22/2006
  Q: Why is iridium more common in space objects than on earth?
  A: Actually, the *conjecture* that iridium (Ir) is more common in space objects (e.g. asteroids) was ...
light & matter9/15/2006
  Q: What is the difference between atomic weight & number? thanks!!
  A: The atomic number is the number of protons (or electrons) of an atom. It also goes by the name of ...
Sun's Altitude on Equator9/7/2006
  Q: I would like to know what is the Sun's maximum altitude on the Equator during vernal equinox?
  A: On the vernal equinox (Mar. 21), the Sun will always have a declination of zero degrees. This means ...
Dark Matter8/27/2006
  Q: My interest in this is purley motivated by a biblical verse. To be excact, there is a verse in the ...
  A: Most astronomers, based on current data (taken from plotting brightnesses of Type Ia supernovae vs. ...
Sound in space - Part II8/23/2006
  Q: I was reflecting on the following part of your answer “As I already noted, any hypothetical sound ...
  A: It is certainly possible that hypothetical sound or pressure waves can be converted into energy ...
Sound in space8/20/2006
  Q: Just because we can not hear any sound (due to absence of a medium), can we say that there is no ...
  A: Sound exists and is transmitted in an atmosphere because of what we call a pressure wave. That is, ...
Sun position using GPS data and Time, programmed in Labview8/16/2006
  Q: I'm currently busy with making a model of the sun to use in a solar program. This program would ...
  A: I would like to assist you but am afraid that I don't understand where you are coming from with your ...
BB Cosmology8/9/2006
  Q: In quantum cosmolgy, does absolute nothingness exist? I am told that it does and that even Hawkins ...
  A: Okay, you actually have several issues that you are looking to address. First, it is difficult to ...
Light in space8/9/2006
  Q: Is the natural light from distant stars enough to see in space? How bright it will be? Suppose my ...
  A: Because the stars are so distant - their natural light - even in space, would be too faint to see ...
Launching from the moon8/5/2006
  Q: I am a 24 year old graduate in systems engineering, and am currently trying to plan a sci-fi story ...
  A: As far as I can tell the mass you are assigning is not consistent with the density arrived at ...
Becoming an astronomer8/1/2006
  Q: I have always had interest in space and anything related to it. I can sit here for hours and read ...
  A: Becoming an astronomer first of all entails acquiring a grounding in advanced math and physics - as ...
stars7/17/2006
  Q: How does a star die?
  A: Basically, a star "dies" when its energy -radiation production processes can no longer sustain it ...
Venus6/20/2006
  Q: I live in the Southern hemisphere (Brazil) and I have just learned that VENUS has phases - like the ...
  A: The brightness of Venus depends on its apparent angular size in the sky, which in turn depends on ...
Einstein5/12/2006
  Q: I know that Einstein had done a lot of studies on cosmology. I'd like to learn more about his work, ...
  A: The problem with understanding most of Einstein's work, is that it generally requires an extensive ...
black holes5/5/2006
  Q: stahl, i once read that a black hole can move through space. i was wondering if this is true and ...
  A: Unfortunately, the source of your puzzlement arises from a misconception about black holes, e.g. ...
distance5/3/2006
  Q: how many kilometres from the sun to earth? from earth to venus and earth to mercury?
  A: You do not stipulate what specific distances you want, so I will assume you want the mean distance ...
galaxies4/26/2006
  Q: how fast do galaxies travel through space?
  A: Galaxies undergo a variety of motions, including rotation and recession (as part of galaxy ...
solar system4/22/2006
  Q: how was the moon formed
  A: The origin and formation of the Moon is still a matter of conjecture. At present, at least four ...
Space physics laws3/28/2006
  Q: We are all aware of the science laws which we invented, my question is wheather this laws are ...
  A: So far as we can determine, the physical laws forged here on Earth apply throughout the cosmos. For ...
Weight vs Mass3/2/2006
  Q: Some object on Earth's surface has a weight of 81 kg. To translate that into mass I can use the ...
  A: First of all, we need to examine the units. In the case of your object, 81 kilograms (kg) is the ...
In space, is there a north, south, east and west?3/1/2006
  Q: my name is Tom Moorby and I am currently studying at Canterbury University in the South Island of ...
  A: Compass directions such as North, South, East and West only serve a viable purpose when there is a ...
manned flight to mars2/27/2006
  Q: With our current technology how long would it take to get to mars, from the closest position mars ...
  A: With our *current propulsion technology* (e.g. no major breakthroughs in ionic or other designs for ...
The Sun's Energy!2/15/2006
  Q: I have been doing some research about the sun and have gotten interested in the energy the sun ...
  A: Okay, let's first start at the beginning and how the Sun's energy originates in the first place. ...
Andromeda/Milky Way collision2/11/2006
  Q: I have red that the Milky Way and Andromeda galaxies are headed towards eachother (at about 300,000 ...
  A: The Milky Way and Andromeda are two members of what is called "the Local Group" - comprising about ...
Solar system / Sun1/20/2006
  Q: I am curious about recent or new discoveries or theories that suggest the sun is other than an ...
  A: Personally, I've seen nothing in recent research papers to convince me the Sun is anything other ...
How fast am I going?1/18/2006
  Q: How fast am I going? This is composed of a number of questions, of which the last is probably the ...
  A: The first (as well as last in the paragraph) cannot be answered and I will get to that. The solar ...
Methane Gas1/14/2006
  Q: Phil, One of my grandsons has asked me why methane is abundant in the cosmos?.... It really has me ...
  A: Most of the methane detected in the cosmos probably comes originally from molecular clouds ...
nebulas12/29/2005
  Q: I frequently read that nebulas are made up of "gas and dust." I'm wondering what kind of gas and ...
  A: Nebulae actually come in a variety of physical types: Diffuse nebulae, which can be emission or ...
the sun12/22/2005
  Q: I would like some information on solar flares. What causes them? What are the effects? Any other ...
  A: I don't understand why you didn't receive the original answer to this question, which was sent more ...
Production of heavy elements12/13/2005
  Q: I read in a book that productoin of elements in the core of stars is terminated to iron. how heavier ...
  A: The theoretical answer as to how the heavy elements are produced was probably first presented by ...
How do they find the positions...12/12/2005
  Q: How do they find the positions of planets and stars (mathematically)...i.e without a star map. and ...
  A: Determining the position of any planet in the orbital plane is not trivial at all, nor can it be ...
Shadow Length12/1/2005
  Q: I would like to know at what time/sun angle over a given place on earth does the shadow of an object ...
  A: and please note the *correction of notation* (LAT to ALT) note - for my previous reply. A very ...
stars11/28/2005
  Q: Is a dark area on the sun caused by magnetic storms,called sunspots?
  A: Actually, rather than "magnetic storms", sunspots are cross-sections of large magnetic "tubes" on ...
telescopes11/25/2005
  Q: I have a bit of a question regarding telescopes and binoculars. My father is a big space buff, and ...
  A: I think the instrument you may find ideal is the Astroscan telescope - offered by Edmund Scientific ...
Aurora Borealis11/8/2005
  Q: I realize that the cause of the Aurora Borealis is from the particles from the sun hitting our ...
  A: The intense energy needed to drive particles that generate a brilliant aurora comes from violent ...
how do tides change at a point...9/28/2005
  Q: how do tides change at a point on the seashore over the course of a day?
  A: The question is actually somewhat too vague to answer in any specific way. For example, a key point ...
astronomy9/16/2005
  Q: I'm doing a beginners course on astronomy and I was wondering if you know some information about ...
  A: My policy in regards to school assignments is strictly not to offer any direct help. However, I can ...
looking for a project subject9/10/2005
  Q: I want to work on an astronomical project and I'm looking for a subject, and is better if the ...
  A: Perhaps the best type of project which meets all the criteria you are looking for, is that of ...
Ages of Universe and Earth/Big Bang8/30/2005
  Q: Philip: Has modern science proven beyond a reasonable doubt the ages of the Universe and Earth? How ...
  A: First, before addressing your specific questions, let's consider what "proof" means and if ...
historical accounts7/23/2005
  Q: I'm a recent college grad. I was talking a lifer friend of mine (he's been in college for 6 years) ...
  A: The alleged stoppage of the Sun for one day is manifestly unfounded, and can be shown so from ...
Jupiters7/21/2005
  Q: why is Jupiters mass greater than Saturns
  A: Jupiter has the equivalent of 318 Earth masses, and Saturn 95. Most of this difference can be ...
Void7/21/2005
  Q: Do we have a hypothesis or deduction with regard to what could be a void (something that lacks ...
  A: If one postulates an absolute void, without matter *or* energy, one in effect postulates something ...
Earth's Orbitory Movement6/29/2005
  Q: Does the speed of the earth's orbitory movement slow down over time? Does the speed of earth's ...
  A: First, the investigation of Earth rotation is not a simple matter. The reason is that the Earth ...
flames in space?5/19/2005
  Q: OK time for some theory. I have always wondered this, and even asked straightdope.com (no answer of ...
  A: According to the General Theory of Relativity and its ‘Principle of Equivalence', inertial and ...
true?5/11/2005
  Q: ?? 1/3 OF THE EARTHS POPULATION WILL BE GONE IN A TWINKLING OF AN EYE. HOW? WHEN THIS CELESTIAL ...
  A: What you referenced on the net shows a mish mash of assorted speculations - none of which has been ...
i am writing a fantasy novel...5/11/2005
  Q: i am writing a fantasy novel about a small planet where it is always nightime. its only source of ...
  A: Unfortunately, the scenario that you propose isn't really physically plausible. (Light only reaching ...
one on moon phases and one on Venus5/2/2005
  Q: Does the moon really appear full for 3 days and dark for three days between the last cresent and the ...
  A: Technically speaking, the Moon can only be "full" at a precise astronomical moment - defined by ...
Earth4/28/2005
  Q: What would happen if the Earth stopped rotating?????
  A: If Earth stopped rotating, all life on it would eventually perish because of the unequal heating ...
Earth4/27/2005
  Q: Would the shadows be affected if the earth stopped sping?
  A: If the Earth stopped spinning, 'shadow' conditions would remain exactly as they were at the time it ...
Earth's Orbit4/24/2005
  Q: If the Earth stopped revolving around the Sun what do you think would happen to all the people on ...
  A: If the Earth stopped *revolving* around the Sun, there would no longer be any centripetal force to ...
Earth Day4/22/2005
  Q: If it takes 23.93 hours for the earth to spin around once, but we have a 24 hour clock, then how do ...
  A: The answer is that we don't "adjust our clock accordingly". The deviations to which you refer are ...
Earth and Planets4/22/2005
  Q: If the Earth stopped revolving around the sun would the otherplanets in our solor system be ...
  A: If the earth stopped revolving around the Sun, yes - the other planets would be affected in various ...
Earth and Gravity4/22/2005
  Q: If the Earth stopped revolving hoe would gravity be affected?
  A: If the Earth stopped revolving the force of attraction that determines weight would be affected but ...
Earth's Rotation4/19/2005
  Q: What would happen if the Earth stopped rotating gradually and stopped but eas still revolving and ...
  A: There is a wide variety of consequences that can occur if rotation stops, or slows. Unfortunately, ...
earth4/19/2005
  Q: How was the earth created and when will the sun blow up.
  A: The Earth formed (with the other nine planets of the solar system) about 4.5 billion years ago when ...
asteroids/comets4/9/2005
  Q: If there was a large comet or asteroid on a collision coarse with earth, would we know before it ...
  A: If enough resources, telescopes were trained on the sky - then yes, astronomers would be able to ...
My question is going...4/8/2005
  Q: My question is going to sound a little crazy but please If u can answer it, Then please do. ...
  A: The only thing that could possibly make the Earth's rotation direction change, even a little, would ...
sun4/2/2005
  Q: helllo if the sun were to turn into a black hole would it consume earth? do you think earth will ...
  A: There is absolutely no chance that the Sun can ever turn into a black hole - either in the next 100 ...
Solar filters2/22/2005
  Q: Can I cover the objective lenses of my binocular with mylar film and use it to view the sun? Are ...
  A: If it were me, I wouldn't do it - since mylar comes in varieties - advertised as 'mylar' - but not ...
I was wonderomg, what is the...2/18/2005
  Q: I was wonderomg, what is the average life span of a star? How long has our sun been around? How much ...
  A: The average life span for a star depends on the type of star (e.g. distinguished in terms of mass, ...
Star-Quake2/18/2005
  Q: I've just read this news story on the BBC website. "Astronomers say they have been stunned by the ...
  A: The location and determination of extra-solar planet positions in large measure depends on the ...
Eccentricity of an Ellipse2/16/2005
  Q: Is there any way to calculate the eccentricity of an ellipse when ONLY the semi-major axis is given? ...
  A: Unfortunately, the sort of calculation you seek is not possible. This is because the figure known as ...
Hi Philip I was wondering:...2/16/2005
  Q: I was wondering: Exactly how dense is the atmosphere of Neptune? I have tried to find out on my own ...
  A: Unfortunately, the density of Neptune's atmosphere is not exactly known. To do this, calculate such ...
distances in space2/10/2005
  Q: I have spent many years looking to find out how scientists have come to the conclusion that the ...
  A: The methods for measuring distance in astronomy are now so exhaustive and diverse, that it would ...
the sun's appearance2/4/2005
  Q: I have experienced this a number of times and so far cannot find anyone else who has seen the same ...
  A: Your observation of a "blue Sun" at the time you describe sounds truly fascinating. Especially as ...
foci2/4/2005
  Q: I was watching the 2nd DVD of Cosmos yesterday and Sagan was discussing Kepler's laws of planetary ...
  A: Carl Sagan's 'Cosmos' series is excellent, and I am glad you're able to see it again. It will ...
Actual Observation of 0h.R.A.in the night sky.1/29/2005
  Q: Where,in the night sky,does an elementary amateur astronomer find the zero meridian Right Ascension?
  A: The most direct and easiest way to locate the 0h R.A. line (which, of course, is imaginary!) is to ...
TRIVIA HELP ME PLEASE!!!!!!1/28/2005
  Q: The sun surly does not emanate from here. Take a look at the front and then look to the lowest ...
  A: I really have no idea what you are asking - and hence need clarification in order to give a reply. ...
light travel1/16/2005
  Q: If a space craft which was able to withstand the temperature and pressure of a travel to the edge of ...
  A: First of all, it must be clarified that there is no "edge" to the universe. All current observations ...
Super organism universe.1/7/2005
  Q: Can we view the universe as an super organism (explain)? Sincerely, Max.
  A: No, the universe can't be viewed as a "super organism" because it has no organic attributes. It ...
sky color on other planets1/6/2005
  Q: What factors influence what color the sky will appear (if viewed from a planet or moon's surface) - ...
  A: Since the color of sky is determined by scattering (by particles in the atmosphere) then Rayleigh's ...
the northern lights1/6/2005
  Q: i think i read somewhere that the northern lights were the result of a solar jet stream or something ...
  A: You can visualize the Earth as a giant spherical magnet, with magnetic field lines extending from ...
Aviation and Space Science12/30/2004
  Q: My organisation [NYDT] set up the Africa Space School for schools in [Southern] Africa. We have an ...
  A: I would be most willing to assist in providing some questions, but first need to know several items: ...
space elevator12/27/2004
  Q: Is it possible to connect a space elevator from Earth directly to a space station if the station is ...
  A: Although the "space elevator" has been repeately tossed around in one guise or another, I don't ...
Light from Stars12/25/2004
  Q: I thought about the light we see from stars and many stars it takes millions and some billions of ...
  A: There are several problems with your assumptions: i)Light lacks mass, so is not subject to the ...
Star core temperature12/17/2004
  Q: I am doing research on stars for a book I am writing, but I am also an engineer so feel free to ...
  A: I think that two separate considerations are being conflated in the reference you cited. That is, ...
quick qeustionaire12/16/2004
  Q: my name is Justin Kerr. I am an aspiring astrophysicist in the 9th grade. I'm working on a research ...
  A: First, some initial information. "Astrophysics" has actually become quite a vast discipline, which ...
Reasons for looking up12/15/2004
  Q: Please tell me about the research that you and other astronomers you know are working on at this ...
  A: "Astronomy" is actually quite a vast discipline to try to explain at one time - even particular ...
Our Suns path through the Zodiac12/14/2004
  Q: My next question was asked of one of the other experts who said the question was out of their ...
  A: First of all, it is important to recognize that the motion of the Sun alluded to is really only an ...
Earths North and South Poles12/13/2004
  Q: Stahl, I have two questions. My first question is what causes the movement of our North and ...
  A: First, the precession of the equinoxes - which is the technical term for the 'wobble' to which you ...
I think the doppler shift...12/7/2004
  Q: I think the doppler shift of the suns emission lines detected on earth should be affected by the ...
  A: Most general references in astronomy, including first year texts, tend to avoid particulars such as ...
Tilt of the Earth's axis.11/20/2004
  Q: I have a question for a book I'm writing, I'm hoping you can answer it. I want to have the axis of ...
  A: To understand how a planet like Earth would be affected by having its axial tilt changed, one only ...
Moon Sighting11/15/2004
  Q: I was wondering if it was scientficly possible to see the crescent of the moon with the naked eye on ...
  A: According to my lunar almanac computer program, on the date you specify - the Moon would technically ...
sun11/11/2004
  Q: How do astronomers know that there is hydrogen and helium in the sun?
  A: Astronomers use a device called a "spectroscope" which is mounted on telescopes. The spectroscope ...
The earth revolves around the sun11/11/2004
  Q: Stahl, Without referring to any scientific text, how do I know that the earth revolves around the ...
  A: First a word on scientific process, "knowing" and "proof". In scientific inquiry, there is actually ...
Saturn10/27/2004
  Q: I'm currently working on a Science Inquiry. Consulting with an expert is part of the process, and ...
  A: Here are the answers to your inquiry questions in turn: 1) Light, as electromagnetic radiation, ...
Hi Philip, I have asked...10/20/2004
  Q: I have asked this question of other sites but have not received a response and since you have ...
  A: Understanding that this is purely speculative, and not intended to be anything at 'textbook' level ...
astronomy10/17/2004
  Q: Question #1 How did astronomy become a science? Question #2 How new tools affected the phase of ...
  A: Astronomy became a science from the time that careful measurements were made and consistently ...
Is the Universe REALLY expanding...?10/13/2004
  Q: What if the universe is not expanding but rather being pulled? Do you think it's possible that there ...
  A: Not only is there new evidence indicating the universe is expanding, but that this expansion is ...
astronomy9/19/2004
  Q: AFTER LEARNING THAT THERE IS NO SUCH THING AS A PERFECT VACUUM, WHAT IS THE VACUUM OF OUTER SPACE? ...
  A: First, space is 'cold' not because it absolutely 'lacks heat' but because its density (of particles) ...
quote...9/7/2004
  Q: i was reading about string theories and came across these few paragraphs.... "Is spacetime ...
  A: The author you cited is not breaking any really new ground for insight, so far as I can see, only ...
choosing telescope8/30/2004
  Q: What telescope do you recommend? I have $400. Thanks. Mike.
  A: The telescope I always recommend to beginners in astronomy is the Edmund Scientific "Astroscan". It ...
Fusion and Iron8/27/2004
  Q: I saw an episode of Nova yesterday that covered black holes and how they're formed. It touched on ...
  A: Beyond a given threshold, the mass of the star doesn't really dictate or portend how far fusion ...
The Cassini Mission8/22/2004
  Q: Has The Cassini Mission launched in 1997 reached Saturn and do you have any good interrnet sources ...
  A: Perhaps the best 'one stop beats all' site is the NASA - JPL site: ...
Sag DIG8/4/2004
  Q: I'm reading about the Milky Way, clusters etc and i came across the term Sag DIG. Can you please ...
  A: SAG refers to the region of the Milky Way in which the object referenced was found, abbreviation for ...
ly7/29/2004
  Q: What is ly? For example, "The Galaxy is 100,000 ly across and 2,000 ly thick".
  A: The abbreviation 'ly' is used for light year, a measure of distance used in astronomy. It is the ...
Capella7/14/2004
  Q: When I view Capella with an unaided eye or binoculars it seems to glitter and cast different colors ...
  A: The effect is related to *scintillation* - the same which produces the "twinkling" of stars. ...
the sun and other stars7/9/2004
  Q: Iwould just like to know of the interactions going on inside the sun and other stars. I read a ...
  A: Basically, you can think of the Sun as a typical "garden variety" star. It is a gigantic, ...
Asteroids passing earth6/26/2004
  Q: The ending of the movie "Armaggedon" has the hero splitting the asteroid at the last second and the ...
  A: First, it's very unlikely - despite the movie- that a nuclear strike on a major asteroid (say > 3 km ...
Cyclical Lunar Extremes of Declination6/17/2004
  Q: Philip Stahl: My question follows the background statement: I visualize the 18.61 year rotation of ...
  A: I am unsure exactly what you are asking here, so will approach it in a general way. If that requires ...
planetismals6/16/2004
  Q: I want to know what the planetismals are, please.
  A: Planetesimals refers to a phase in the build-up process toward planet formation in a young solar ...
astronomy6/15/2004
  Q: Why does the earth rotate counterclockwise around the sun?
  A: The direction of Earth's *revolution* about the Sun (not rotation, which is what we mean by the ...
Mars' Atmosphere6/10/2004
  Q: I understand that Mars' atmosphere is very thin to the point that the air pressure is 1/100 that of ...
  A: In all likelihood, what happened is that Mars' atmosphere was "outgassed", e.g. the particles - ...
local noon5/20/2004
  Q: how you doing? I have a few questions about the sun. My first question is how does local noon ...
  A: Actually, your questions more concern timekeeping and its basis. To understand local noon, you need ...
Fallacies of the Big Bang theory5/13/2004
  Q: we have a discussian at my church about a big bang theory and i just wondered if there is any ...
  A: So far as I am aware, there's no scientific evidence that can't be incorporated into at least one ...
proxima centuri5/12/2004
  Q: How would you describe the star "proxima centuri" and how does it compare with our sun? Is proxima ...
  A: Proxima Centauri is a red dwarf companion to Alpha Centauri, smaller than the Sun, less massive and ...
Space5/3/2004
  Q: This is a silly blonde question. The Sun warms the Earth and yet space is extremely cold, why ...
  A: First, two short answers to your two questions: Space in general hasn't the 'mass to be warmed', ...
theory5/2/2004
  Q: The condensation theory says that the planets developed through coagulation of dust grains in a disk ...
  A: Objects called meteoroids (which you can think of as very small asteroids), asteroids and comets all ...
Hello4/22/2004
  Q: I have been looking online for a service that registers star names as gifts to people. I understand ...
  A: Star names are normally assigned and determined by the International Astronomical Union (IAU) and ...
just 2 short clarifications4/17/2004
  Q: I was just reading a book on Planetary Rings and these two questions came to me as I read. Have the ...
  A: In the case of Saturn, the rings were probably there since its formation in the early Solar System. ...
earth4/14/2004
  Q: Right now the earth axis is tilted, but if it was not tilted then what would happen? I know that due ...
  A: If the Earth had no axial tilt, the Sun would never change its declination - meaning that it would ...
planets4/10/2004
  Q: Jupiter, Saturn and Neptune all radiate more energy than they receive from the sun. There seems to ...
  A: The gas giant planets you mention probably radiate a bit more energy than they receive for at least ...
Comets4/10/2004
  Q: Could you please explain, in as much detail as reasonably possible, what causes comets to follow ...
  A: In fact, all the bodies of the solar system follow elliptical orbits, they simply vary in what we ...
s4/7/2004
  Q: Roughly how much raw material gets blasted out from the sun in the form of charged particles and ...
  A: The solar wind in its normal, quiescent mode - at around the Earth's distance from the Sun (1 AU or ...
moon and tidal braking4/4/2004
  Q: Stahl, I don't quite understand how even if the moon is spinning, why is it not subject to tidal ...
  A: The basis of your question resides in the principle of conservation of angular momentum. To put it ...
Sun's life-span, Mars exploration3/31/2004
  Q: Do you know when our Sun will burn-out? Or does it expand firt? I guess what I am asking is how much ...
  A: The Sun will continue as a stable star for at least as long as its supply of hydrogen lasts. ...
Universe inflation3/12/2004
  Q: Within the context of the inflation of the universe denoted by red shift, are the stars WITHIN ...
  A: You raise an important question. A relevant point to note is that all objects external to our Local ...
Position of planets3/10/2004
  Q: What keeps a planet in its place relative to other neighboring planets and what causes a planet to ...
  A: Your answers in turn: 1) Planets are not all necessarily "kept in place" relative to neighboring ...
Planetary Rotation3/2/2004
  Q: Orbital speed decreases as the distance from the orbital focus increases. As rocky planets like the ...
  A: So far as we believe, and I underscore this is still tentative *theory*, the outer planets formed ...
sunspot2/27/2004
  Q: Why do sunspots appear dark in visible light? is it because they only appear dark against the ...
  A: Sunspots represent cross-sections of large magnetic "tubes" in the Sun, from 5,000 km to 70,000 km ...
Saturn2/26/2004
  Q: Would ecolocation be able to locate amonia clouds on saturn?
  A: Spectrophotometers could do it, and the precision would depend on whether they were aboard ...
Astro Physics2/25/2004
  Q: I have read that it takes light from the sun about 9 min to reach earth. If so ... that means that ...
  A: Follow-up: The next to last paragraph should read: "By the same token, at *visible sunrise*, the ...
thermal spectrum2/21/2004
  Q: Does a thermal spectrum emitted by an object have a peak? or does it have the same intensity at all ...
  A: All radiating objects have a thermal spectrum that radiates at all wavelengths of the EM ...
sun2/20/2004
  Q: I know that nuclear fusion reactions takes place in the core of the sun where the temperature and ...
  A: Most of our work on Earth, in plasma physics labs, shows that you can't just have fusion reactions ...
How did the xrays escape the black hole?2/20/2004
  Q: I was watching TV and saw for the first time a actual star get absorbed by a Black Hole. What got my ...
  A: I haven't seen the program of which you speak, but x-rays generally indicate the accretion of the ...
Detection2/19/2004
  Q: Why can't we use normal light (observable light) to detect the birth of stars and protostars but ...
  A: Proto-stars have not yet ignited their nuclear cores, so are still burning by *contraction* only - ...
Gravity2/17/2004
  Q: Why do planets and other bodies go into orbit except for crashing straight into eachother? (ex. the ...
  A: Planets and other celestial objects are really in a state of free fall. Consider a satellite ...
instance2/15/2004
  Q: My professor posed the question, that supposing there is a planet twice the mass of the Earth ...
  A: Yes, you're correct. The new period is only insignificantly larger than 1 yr. The Newtonian casting ...
astronomy2/12/2004
  Q: What is astronomy? When did it first start or whatever?
  A: 'Astronomy' is actually quite a large area to try to explain at one time because it isn't just one ...
Astronomy2/9/2004
  Q: Is it possible to approximate the weight of the sun? If so, what has it been calculated to be? ...
  A: "Weight" is a measure of gravitational attraction to a reference body, on which the weighed object ...
Sun and Moon angles2/1/2004
  Q: i was asked this question by a professor in class, and im still stumped. the question is this: The ...
  A: Yes, I myself have always referred to it as a "startling coincidence" given the fact the Moon is ...

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Philip Stahl

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I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.

Experience

Astronomy: Worked at university observatory in college, doing astrographic measurements. Developed first ever astronomy curriculum for secondary schools in Caribbean. Gave workshops in astrophysics and astronomical measurements at Harry Bayley Observatory, Barbados. M.Phil. degree in Physics/Solar Physics and more than twenty years as researcher with discovery of SID flares. Developed of first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Develop first ever loop solar flare model using double layers and incorporating cavity resonators.

Organizations
American Astronomical Society (Solar Physics and Dynamical Astronomy divisions), American Mathematical Society, American Geophysical Union.

Publications
Solar Physics (journal), The Journal of the Royal Astronomical Society of Canada, The Proceedings of the Meudon Solar Flare Workshop (1986), The Proceedings of the Caribbean Physics Conference (1985). Books: 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level'. 'Astronomy and Astrophysics: Notes, Problems and Solutions'.

Education/Credentials
B.A. Astronomy, M. Phil. Physics

Awards and Honors
American Astronomical Society Studentship Award (1984), Barbados Government Award for Solar Research (1980), Barbados Astronomical Society Award for Service as Journal Editor (1977-91)

Past/Present Clients
Caribbean Examinations Council, Barbados Astronomical Society, Trinidad & Tobago Astronomical Society.

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