Expert: Tom Whiting - 12/4/2009

Question
Good evening Mr. Whiting

I have a few questions regarding starlight.  

If starlight is electromagnetic radiation how many parts of this radiation are used by astronomers?

What type of instruments works best with each?

Are there any "special" instruments that work in conjunction with telescopes to advance our studies of starlight?

Also, it appears as though there have been multiple full moons over the past few nights (I recall reading about an rainbow like ring around the moon? last weekend) as well as the different phases of the moon.  Is this normal for this time of the year?

I woul greatly appreciate any feedback.

Thank you.  :)  

Answer
All of it.
Starlight is composed of radio, infrared, visible light, UV, X-ray and gamma rays, the
entire realm of the electromagnetic spectrum. Astronomers examine and study all of them.  We use radio telescopes and visible light telescopes on Earth, and IR and UV and X-ray and Gamma ray "telescopes" (or detectors) in orbit to analyze all the incoming radiation...at times.  Those last four varieties of photons generally have to be gathered in orbit because our atmosphere is opaque to most of those photons.
Instruments include spectrometers and CCD cameras, photometers for counting photons,
and probably some other new equipment I've never heard of....dealing with computers and
computer analysis.  I'm not that up on it (special equipment that the professionals use) because I am strictly eyeball to the eyepiece with a telescope, so I'm only concerned with visible light.
I don't even do pictures with a camera.

There is only one full moon in a 29.5 day lunar cycle and that occured on December 2nd
at exactly 0731 GMT...I don't know your location so you'll have to convert that to your local time. (For EST it's -5 hours so it's 2:31 am EST.) At that exact time the moon was exactly 180
degrees, exactly opposite from the sun in our sky. This will occur again on December 31st at 1913 UT or 2:13 pm EST. (Yes, December has 2 full moons).  So on the evenings just before, and just after, those dates...the moon may LOOK full to the common layman, but it really isn't. If you look very closely, you'll see that one side or the other isn't quite filled out completely.
Since the moon moves eastward, it's the east side (left hand side) not completely filled out prior to full moon date, and the western side after the full moon date.

Haloes are a weather event caused by high altitude ice crystals in the air, generally up
in the stratosphere. I don't know if they are more common in our winter... or any time of the year as it's so dependent on weather and frontal passages. Anytime you see light, thin cirrus clouds, there is always a chance for a halo (22 degree is the most common halo) and related halo phenomenon...moon dogs, upper tangential arcs, parry arcs, etc. So it's normal anytime of the year when you have frontal zones passing through your region...again, you don't specify a location.  For more information, you can google those terms.  The same haloes and halo effects also apply to the sun too.

Oh, the phases of the moon are simply the fractional amount of lunar surface illumination
that we can see from earth, depending on the Sun-Earth-Moon angle. About one week after full
moon is last quarter (rising in east around midnight) because the moon is at 90 degrees from the sun-Earth alignment. New moon is about 7 days after that when the moon is in the sun's vicinity
(therefore the far side of the moon, not the near side, is fully illuminated, so we can't see it). Then about 7 days after that it moves to 1st quarter (setting in west around midnight) because again it's 90 degrees from the sun-earth alignment, but on the other side of the sky, so it's our first quarter phase. Then another 7 days we're back to that 180 degree full moon angle again. (Which of course is a straight line).
And the cycle begins again. This has been going on for over 3 billion years now.
Clear Skies,
Tom Whiting
Erie, PA USA