Moon Gazing PREFLIGHT
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The following questions refer to the material you were to read in preparation for the lesson.

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Atmospheric Turbulence

The following animated GIF is a simulation experiment of atmospheric turbulence. You've seen the phenomenon when you see "heat waves" above a hot road, or above a hot car hood. When this happens in the atmosphere, it makes the light from a star "twinkle", which of course, would blur a long time-exposure photograph.
(Unfortunately, it is 2 MBytes large, so don't click this link unless you have reasonably fast Internet access!)
TURBULENCE

This turbulence in the atmosphere causes "bad seeing" conditions for telescopes. SO despite having large mirrors, the telescope only achieves 1" (one arcsecond) typical resolution. That is, a star gets blurred into at least a 1" blob. The best seeing in the world appears to be on top of Mt. Mauna Kea in Hawaii, where 0.5" is sometimes possible. However, within the last 15 years, a new technique has become possible that tries to "undo" the turbulence. It's called adaptive optics, and it involves a "rubber mirror" which can be distorted in exactly the opposite sense to the atmospheric turbulence, to neutralize the atmospheric effect. Here's a before and after example of that process looking at a star cluster known as M13:

If you have a good connection, here's a marvelous animated gif that shows what happens when the telescope "turns on" it's turbulence correction, or "closes the loop" of it's feedback controls. Its 1.5 MB, so again, don't click unless you have a fast connection.
Keck Telescope Movie

Question: The book gives a series of huge telescopes in a table on page 142. A new telescope they didn't mention is the "Overwhelmingly Large" telescope, or OWL, which is planned to be 11 meters in diameter. What is the theoretical resolution of this telescope at 500 nm wavelength if it were on the Moon? What is the resolution on Earth looking through the atmosphere? What is the resolution expected with adaptive optics?



honors extra


Lockheed-Martin Concept
NASA GSFC concept
TRW Concept
Question: So with the ability to make photographs BETTER than the $2 Billion Hubble Space Telescope, and to do it on the ground for only a $100 Million or so, why is NASA proposing a "Next Generation Space Telescope" in space for another $Billion or so!?




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