Astronomy - Space and Astronomy for Kids - Science

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About Philip Stahl
(Top Expert on this page)

Expertise
I have 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 as applied to astronomical investigations.

Experience
Astronomy: more than forty years experience starting with construction of my own simple telescopes. Worked at university observatory in college, doing astrographic measurements. M.Phil. degree in Physics/Solar Physics and more than ten years as researcher.

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Questions Answered By Expert Philip Stahl
In Category Astronomy

Subject	Date Asked

Crystalline patterns in meteorites	11/19/2009
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 ...
Neutron star formation with different forces	11/10/2009
Q: Would it be possible that a collapsing star directly become a neutron star without lightening up if ... A: again, Your speculations are quite interesting (as are Susskind's) - but in general I tend to be ...
Hyper Novas & Galaxies Black Holes	11/10/2009
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 forces	11/9/2009
Q: Would it be possible that a collapsing star directly become a neutron star without lightening up if ... A: The trouble with most appeals to some kind of "fine tuning" of the constants of nature is: 1) most ...
Neutron star formation with different forces	11/9/2009
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 Periods	11/7/2009
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 radiation	11/2/2009
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 cosmos	9/28/2009
Q: Where is cosmology now on the overall shape of the universe? Is it a big sphere, with the galaxies ... A: Okay, well I wasn't quite sure what your background was, so preferred to err on the side of caution ...
geometry of the cosmos	9/27/2009
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 day	9/24/2009
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 explosion	9/21/2009
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 planets	9/21/2009
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 phenomenon	9/16/2009
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 holes	9/9/2009
Q: I've read that the laws of physics break down in a black hole, but specifically, what laws? It ... A: Yes, it can continue to consume....and consume.. Don't forget the existence of the singularity at ...
black holes	9/8/2009
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 world	9/7/2009
Q: iv read so many things on the Mayan Prophecy and it said that the planets will alighn with the ... A: Well, there is nothing to be "freaked out" about. It is all super-hype, designed to sell ...
end of the world	9/6/2009
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 ...
physics	9/5/2009
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 Spheres	9/3/2009
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 Bang	8/28/2009
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 ...
CMB	8/18/2009
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 dynamics	8/18/2009
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 earth	8/14/2009
Q: I heard something within the last year, probably on NPR, regarding the origin of our planet and the ... A: again: you wrote: "I want to emphasize that it might not have been NPR. " Okay, fair enough. That ...
origin of planet earth	8/14/2009
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 Spirals	8/13/2009
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 shower	8/12/2009
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 hole	8/11/2009
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 Parallax	8/10/2009
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 earch	8/3/2009
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 Relaxation	7/13/2009
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 spirals	7/11/2009
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 galaxies	7/9/2009
Q: I would like to know how many years it takes for other galaxies, large and small, to make one ... A: I consulted the text 'The Galaxies of the Local Group' (Cambridge University Press, 2000) by Sidney ...
spinning galaxies	7/8/2009
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 Change	7/3/2009
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. ...
sun	5/31/2009
Q: how cold would it get on earth if the sun went away ANSWER: Hello, If the Sun "went away" the ... A: True, it does, but the way you posed your hypothetical question as that the Sun 'went away'. E.g. ...
Suns	5/24/2009
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 Path	5/17/2009
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 planets	5/11/2009
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 stars	5/6/2009
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. ...
Astronomy	5/5/2009
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 Path	4/30/2009
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 time	4/30/2009
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 ...
Viewing	4/28/2009
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 ...
space	4/24/2009
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 ...
Solar Image	4/13/2009
Q: I am a amature astronomist. While viewing the son in Feb. of this year, I keep seeing something I do ... A: I just wanted that to be able to rule out any atmospheric or "system" effects. I think the ...
Lunar Eclipse	4/13/2009
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 Image	4/12/2009
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 size	4/10/2009
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 gasses	4/7/2009
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 Attraction	3/29/2009
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. ...
Interview	3/18/2009
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 observations	3/15/2009
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 ...
astronomy	3/9/2009
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 Thoughts	3/8/2009
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 moon	3/3/2009
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 ...
comets	3/2/2009
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 universe	2/28/2009
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 stars	2/26/2009
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 flairs	2/26/2009
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 ...
satellites	2/24/2009
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 law	2/23/2009
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 ...
meteors	2/22/2009
Q: I was looking at two explanations as to why meteors burn as they go through the atmosphere. One says ... A: I think what I meant to say - based on the first reply- is there are two modes, and the ...
meteors	2/21/2009
Q: I was looking at two explanations as to why meteors burn as they go through the atmosphere. One says ... A: The very emergence of the heated gaseous envelope is caused by "friction". You have an object ...
meteors	2/20/2009
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 earth	2/18/2009
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 universe	2/16/2009
Q: Philip, According to current theory, what happens to the light traveling outward past the edge of ... A: Yes. Basically, I am saying that space is expanding at a rate v > c, and as I noted this ...
expanding universe	2/15/2009
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 ...
Geography	2/9/2009
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 Sky	2/9/2009
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 Cancer	2/1/2009
Q: NASA has measured the exact timing when the earth would be closest to the sun, or farthest away from ... A: I am very glad to have been able to help you, Mazin. However, I still beg to differ that using any ...
The two tropics: Capricorn and Cancer	1/31/2009
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 phenomenon	1/29/2009
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 Flares	1/25/2009
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 ...
telescope	1/21/2009
Q: Dr. Stahl, Don't you think it would be worth while to put up another telescope in space that would ... A: Actually, in the current parlous economic environment, I believe that any SOT-type project (costing ...
telescope	1/20/2009
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 Flares	1/18/2009
Q: http://en.allexperts.com/q/Astronomy-1360/2009/1/Flare-activity-earth.htm and for the follow up you ... A: In reference to the rate of discharge of the phenomenon you noted, I don't think it makes any ...
Earth Flares	1/18/2009
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 ...
Astrophysics	1/17/2009
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 Light	1/15/2009
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 universe	1/13/2009
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 ...
geography	1/12/2009
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 ...
Electrical Universe	1/11/2009
Q: Dr. Stahl, I came across an interesting video on Google videos called "Thunderbolts of the Gods". ... A: I suspect you might have me confused with someone else. My position is that until another ...
REAL loss of daylight	1/10/2009
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 sun	1/9/2009
Q: i am 17 years old and i was wondering is it possible that when a star dies and produces a black ... A: Actually, what you have is not a "theory" but a casual speculation about black holes and their ...
black holes and the sun	1/8/2009
Q: i am 17 years old and i was wondering is it possible that when a star dies and produces a black ... A: Sorry, I am aware of no "magnetic waves" or "radio waves" emitted from a black hole. Do you have a ...
black holes and the sun	1/8/2009
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 Universe	1/4/2009
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 Limbaugh	12/22/2008
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 ...
Meteors and meteorites	12/20/2008
Q: Dr. Stahl, What would the difference in appearance be between an iron meteor that is still in its ... A: I think the retrieval option is simply a lower priority (given budgetary limits) right now. Also, ...
losing daylight/ worried	12/19/2008
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 meteorites	12/19/2008
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 cooling	12/16/2008
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 horizon	12/15/2008
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 ...
Seasons	12/14/2008
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 galaxies	12/8/2008
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 equations	12/3/2008
Q: Mr. or Dr. Stahl, Can you direct me to where I might find FORTRAN or MAPLE code for analyzing some ... A: The files I have were accessed via the Mathcad User forums. I did it by clicking on 'Help' in the ...
einstein field equations	12/3/2008
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 ...
John Dobson	12/2/2008
Q: I was wondering if you have heard of John Dobson of the Sidewalk Astronomers, and if so, what do you ... A: I picked up a good synopsis of Dobson's claims at the Wiki link for his name (astronomer), which ...
Axis shift and Global Warming	12/2/2008
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 Dobson	11/28/2008
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 flash	11/18/2008
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 ...
moon	11/17/2008
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 stars	11/14/2008
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) ...
Comet-Like Knots Around a Dying Star in the Helix Nebula	11/13/2008
Q: Dr. Stahl, Please tell me what is involved in the formation of comet-like objects such as those ... A: Good questions all! First, let me emphasize the "cometary" description, not "comets" literally. ...
stars visibility	11/11/2008
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 change	11/11/2008
Q: Sir, Are you familiar with the studies being done at the Danish national space Center(institute) on ... A: I'm really sorry but it doesn't help at all. The first link you posted brings up the message: "The ...
climate change	11/10/2008
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 light	11/10/2008
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 Nebula	11/9/2008
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 revolutions	10/26/2008
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 sky	10/22/2008
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 ...
astronomy	10/21/2008
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 discs	10/19/2008
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 ...
Auroras	10/12/2008
Q: hello, a quick question on the physics of auroras please - i just wanted to confirm the following ... A: I am not aware of any direct measurements of currents being done, only of simulations (numerical) ...
The earths orbit around the sun	10/12/2008
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 - ...
Auroras	10/11/2008
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 hole	9/23/2008
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) ...
CERN	9/20/2008
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 Confusion	9/18/2008
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 ...
astronomy	9/17/2008
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 size	9/12/2008
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 matter	9/12/2008
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 nodes	9/12/2008
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 collider	9/11/2008
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 ...
astronomy	9/10/2008
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 ...
Days	9/5/2008
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 wrote: "Thanks for the answer, but I think you misunderstood my point; I freely admit the ...
Days	9/4/2008
Q: What is the exact definition of a day? If a day is defined as a full spin of the earth on its ... A: Okay - first I don't think "metering" (metric system) is in any way arbitrary. It's actually a much ...
education in astronomy	9/3/2008
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 ...
Days	9/3/2008
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 ...
astronomy	9/2/2008
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 confused	9/2/2008
Q: i swear i read somewhere that for in order a star to be a supernova candidate it has to be over 9 ... A: Nine solar masses is nine times the mass of the Sun. Again, I think your confusion stems largely ...
im confused	9/1/2008
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 Environment	8/23/2008
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 ...
answer	8/21/2008
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 Beach	8/21/2008
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 ...
Orbits	8/15/2008
Q: Why does one sattlite obit the earth while another is in a stationary orbit? ANSWER: This is a ... A: A satellite attains orbit when it is launched at escape velocity - which is about 18,000 mph. If the ...
Orbits	8/13/2008
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 warming	8/7/2008
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 ...
starz	8/1/2008
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 ...
space	7/31/2008
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/energy	7/15/2008
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 ...
wr 104	7/14/2008
Q: i was wondering; since you seem very knowledgeable. -what's your opinion of stars such as WR 10 and ... A: Here's the bottom line: the odds of either of those stars going supernova and "killing us" before ...
galactic alignment	7/14/2008
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 104	7/14/2008
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 Orbits	7/14/2008
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 luminosity	7/12/2008
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 change	7/11/2008
Q: "Question I live in Milwaukee,WI. It's January and the temps have been around 40-50 degrees ... A: Yes, I guess I misunderstood your question. This is fairly easy since the claim of Milankovitch ...
Your question about earth axis' shift and climate change	7/10/2008
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 Science	7/10/2008
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)	7/5/2008
Q: if a type Ia supernova, at the distance of 1000 pc, dumps as much gamma-ray radiation onto the earth ... A: Again, you are confusing different aspects of the problem, in this case global dimming with global ...
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 ...
IK Pegasi (HR 8210)	7/4/2008
Q: As you know IK Pegasi is a binary star system that's 150 lightyears away from earth that has the ... A: I think what the author is saying, is essentially similar to what I have been saying - that any ...
southern cross	6/30/2008
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 ...
Mars Soil	6/27/2008
Q: I want to become an astronomer. I have a Biology bachelor's degree, but I am willing to get a degree ... A: All I have heard in the news is that the Martian soil is found to be "likely to support life". I've ...
Astronomy	6/26/2008
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 Prospects	6/25/2008
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: Well, let's see now, what sort of stories and rumors circulate the net? Last I checked most of them ...
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 ...
universe	6/20/2008
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 period	6/15/2008
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 moon	6/6/2008
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 Brightness	6/5/2008
Q: .. To compute the "brightness" of a star the formula is -- B = L / 4PID^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 plane	6/3/2008
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 Sun	5/27/2008
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 sky	5/22/2008
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 shift	5/14/2008
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 warming	5/12/2008
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 ...
Charts	4/18/2008
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 & Time	4/13/2008
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 systems	4/6/2008
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 flares	3/28/2008
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 astronomy	3/17/2008
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 Sun	3/14/2008
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 Solstices	3/10/2008
Q: I'm not sure you're the right person to ask, but here goes: Why are tides so low at the soltices? ... A: Erin. I removed my profile from being rated about a year ago because I found too many did not know ...
tides at Solstices	3/7/2008
Q: I'm not sure you're the right person to ask, but here goes: Why are tides so low at the soltices? ... A: Erin Actually, I didn't say that the Full Moon "doesn't affect the tides", I said that high tides ...
tides at Solstices	3/4/2008
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 earth	2/22/2008
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 saturn	2/19/2008
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 formed	2/17/2008
Q: How do stars form in clusters or binary when the solar winds from the stars that were formed first ... A: First of all, sorry you did not see a ranking or rating option - but I chose to be "unrated" in this ...
How stars are formed	2/17/2008
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 ...
science	1/17/2008
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 shift	1/15/2008
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 Phenomenon	1/14/2008
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 ...
mars	1/13/2008
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 Physics	1/11/2008
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 ...
Sunsets	1/8/2008
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 experiment	12/18/2007
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 Telescopes	11/9/2007
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 orbit	11/4/2007
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 ...
Comets	10/29/2007
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 ...
Gravitation	10/22/2007
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 ...
Supernovas	10/20/2007
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 Phases	10/16/2007
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 ...
bullets	10/14/2007
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 ...
Moon	10/2/2007
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' revolving	9/24/2007
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 ...
astronomy	9/20/2007
Q: where does the name constellatiions come from A: "Constellation" comes from the Latin, constellatus (con- stella-tus) Con = coming together, ...
dinasour extinction	9/9/2007
Q: I read the following in Science: At approximately 170 kilometers in diameter and having ... A: First, the difference is that the mass of the typical asteroid in the asteroid belt is far less than ...
dinasour extinction	9/9/2007
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 ...
Astronomy	9/6/2007
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 ...
Cloud ring surounding moon	8/30/2007
Q: today , the full-moon day , I am seeing a strange phenomenon , the moon is full and cloud is ... A: I have to stand by what I said previously, that the effect is due to clouds - composed of ice ...
rotation of the earth	8/30/2007
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 moon	8/29/2007
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 Sun	8/25/2007
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 ...
Astroarchaeology	8/3/2007
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. Planet	7/19/2007
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 holes	7/9/2007
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 Sky	7/7/2007
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 astronomy	7/3/2007
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 book	6/25/2007
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 color	5/20/2007
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 ...
Astronomy	5/20/2007
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 ...
Galaxies	5/13/2007
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 sky	5/7/2007
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. ...
astronomy	5/3/2007
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 ...
astronomy	4/25/2007
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 ...
life	4/22/2007
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 ...
heliosheath	4/11/2007
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 ...
STAR	4/10/2007
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 ...
question	4/8/2007
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 credibility	4/7/2007
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 distances	4/5/2007
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 atmospheres	4/5/2007
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 radiance	4/5/2007
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 ...
Space	4/4/2007
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 flares	4/1/2007
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 ...
asteroid	2/19/2007
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 Masses	1/22/2007
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 ...
saturn	1/19/2007
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 warming	1/10/2007
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 1859	1/5/2007
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 ...
astronomy	1/2/2007
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 flares	12/15/2006
Q: I thought that solar flares are on an 11yr cycle- are physicist trying to predict how large / how ... A: Actually it is sunspots that display a mean, 11-year cycle - not solar flares. Some of the largest ...
physics of solar flares	12/14/2006
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 ...
sunrise	12/12/2006
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 intelligence	12/4/2006
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 Stars	11/30/2006
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 ...
Space	11/28/2006
Q: WHy is it impossible that nothing to in space, why does at least one partical have to per cubic ... A: Probably the main reason that "natur abhors a vacuum", at least in space, is that nothing is ...
Movement of the Sun	11/28/2006
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 ...
Space	11/28/2006
Q: Is it that why sound travels faster in water than in air, because the water is thicker than air? And ... A: Yes, this is basically true - and why sound also will travel faster in a steel rod, for example. ...
Space	11/28/2006
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 movement	11/26/2006
Q: Has anyone ever actually seen an atom or a subatomic particle, neutron, electron, or proton and are ... A: Direct observation of atomic - subatomic particles is mostly precluded by their small scale size - ...
Earth's movement	11/25/2006
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 Events	11/18/2006
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 moonsets	10/29/2006
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 location	10/20/2006
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 Mass	10/20/2006
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 gravitation	10/18/2006
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 miss	10/13/2006
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 ...
Sun	10/1/2006
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 ...
iridium	9/22/2006
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 & matter	9/15/2006
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 Equator	9/7/2006
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 Matter	8/27/2006
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 II	8/23/2006
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 space	8/20/2006
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 Labview	8/17/2006
Q: Stahl, Maybe I used the wrong terminology. By solar model I do mean solar energy model. But the ... A: I kind of figured that this is what you wanted - but preferred to make sure on hearing back from ...
Sun position using GPS data and Time, programmed in Labview	8/16/2006
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 Cosmology	8/11/2006
Q: How does One arrive that a quantum event is plausible when the time interval is 0, and thus the ... A: The problem I've usually found dealing with issues such as quantum cosmology, or even cosmic ...
Light in space	8/9/2006
Q: It is a new information to me. From what you say, if I am in space just above the moonless night ... A: If you are above the night side of Earth, there will be extremely faint illumination depending on ...
BB Cosmology	8/9/2006
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 space	8/9/2006
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 moon	8/5/2006
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 astronomer	8/1/2006
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 ...
stars	7/17/2006
Q: How does a star die? A: Basically, a star "dies" when its energy -radiation production processes can no longer sustain it ...
Venus	6/20/2006
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 ...
Einstein	5/12/2006
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 holes	5/5/2006
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. ...
distance	5/3/2006
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 ...
galaxies	4/26/2006
Q: how fast do galaxies travel through space? A: Galaxies undergo a variety of motions, including rotation and recession (as part of galaxy ...
solar system	4/22/2006
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 laws	3/28/2006
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 Mass	3/2/2006
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 mars	2/27/2006
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 collision	2/11/2006
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 / Sun	1/20/2006
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?	1/19/2006
Q: I appreciate the specifics about the answerable questions. As you say, I am asking about the ... A: Ok, lots of stuff to clarify. First, one cannot ascertain a "center" to the universe, because ...
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 Gas	1/14/2006
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 ...
nebulas	12/29/2005
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 sun	12/22/2005
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 elements	12/13/2005
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 Length	12/1/2005
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 ...
stars	11/28/2005
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 ...
telescopes	11/25/2005
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 Borealis	11/8/2005
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 ...
astronomy	9/16/2005
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 subject	9/10/2005
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 Bang	8/30/2005
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 accounts	7/23/2005
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 ...
Jupiters	7/21/2005
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 ...
Void	7/21/2005
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 Movement	6/29/2005
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 Venus	5/10/2005
Q: Okay, first thanks for the second part -- while this may not clarify the mud exactly, at least the ... A: Though the Moon may well “look” full for more than one night, the fact is that it isn't technically ...
one on moon phases and one on Venus	5/2/2005
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 ...
Earth	4/28/2005
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 ...
Earth	4/27/2005
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 Orbit	4/24/2005
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 Day	4/22/2005
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 Planets	4/22/2005
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 Gravity	4/22/2005
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 Rotation	4/20/2005
Q: ------------------------- Over a periodof time like two years or two weeks Followup To Question - ... A: Over a period of only two weeks, the results would be horrendous. As we know - any major slowdown of ...
Earth's Rotation	4/19/2005
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, ...
earth	4/19/2005
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/comets	4/9/2005
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 ...
sun	4/2/2005
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 ...
distances in space	2/28/2005
Q: I have spent many years looking to find out how scientists have come to the conclusion that the ... A: The problem in regard to your request, is the professional Observatories are usually "scheduled to ...
Solar filters	2/22/2005
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-Quake	2/18/2005
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 Ellipse	2/16/2005
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 space	2/10/2005
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 appearance	2/4/2005
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 ...
foci	2/4/2005
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 travel	1/16/2005
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 planets	1/6/2005
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 lights	1/6/2005
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 Science	12/30/2004
Q: ------------------------- Follow up To Hello. I would be most willing to assist in providing ... A: After examining your materials, responses, I think that what's needed is to go to existing teachers ...
Aviation and Space Science	12/30/2004
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 elevator	12/27/2004
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 Stars	12/25/2004
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 temperature	12/17/2004
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 qeustionaire	12/16/2004
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 up	12/15/2004
Q: Please tell me about the research that you and other astronomers you know are working on at this ... A: Unfortunately, the job opportunities here in the U.S. (can't really speak for Canada) are receding, ...
Reasons for looking up	12/15/2004
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 Zodiac	12/14/2004
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 Poles	12/13/2004
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.	11/22/2004
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: The situation at poles and the rest of the planet (for the no tilt case) would be exactly the same ...
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 Sighting	11/15/2004
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 ...
sun	11/11/2004
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 sun	11/11/2004
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 ...
Saturn	10/27/2004
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 ...
astronomy	10/17/2004
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 ...
astronomy	9/19/2004
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 telescope	8/30/2004
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 Iron	8/27/2004
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 Mission	8/22/2004
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 DIG	8/4/2004
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 ...
ly	7/29/2004
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 ...
Capella	7/14/2004
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 stars	7/9/2004
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 earth	6/26/2004
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 Declination	6/17/2004
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 ...
planetismals	6/16/2004
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 ...
astronomy	6/15/2004
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' Atmosphere	6/10/2004
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 noon	5/20/2004
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 theory	5/13/2004
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 centuri	5/12/2004
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 ...
Space	5/3/2004
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', ...
theory	5/2/2004
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 ...
Hello	4/22/2004
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 clarifications	4/17/2004
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. ...
earth	4/14/2004
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 ...
planets	4/10/2004
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 ...
Comets	4/10/2004
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 ...
s	4/7/2004
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 braking	4/4/2004
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 exploration	3/31/2004
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 inflation	3/12/2004
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 planets	3/10/2004
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 Rotation	3/3/2004
Q: Orbital speed decreases as the distance from the orbital focus increases. As rocky planets like the ... A: You're reasoning is actually faulty because it's based on a false analogy. You are likening the ...
Planetary Rotation	3/2/2004
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 ...
Astro Physics	2/27/2004
Q: I guess that your did answer the question I asked but That is not what I wanted to ask. I'll try ... A: You asked: "I have read about the quest of things that might be travling faster than the speed of ...
sunspot	2/27/2004
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 ...
Astro Physics	2/27/2004
Q: ------------------------- Followup To Either I missed part of your answer to my question or I ... A: I suspect the first part of my answer wasn't provided, so will give that again. If this still ...
Saturn	2/26/2004
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 Physics	2/25/2004
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 spectrum	2/21/2004
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 ...
sun	2/20/2004
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 ...
Detection	2/19/2004
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 - ...
Gravity	2/17/2004
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 ...
instance	2/15/2004
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 ...
astronomy	2/12/2004
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 ...
Astronomy	2/9/2004
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 angles	2/1/2004
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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