Thread: Apollo 13 Hoax?
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Old 05-November-2001, 01:11 AM
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The Bad Astronomer The Bad Astronomer is offline
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I didn't say it is as reflective as a mirror or fresh fallen snow. But I can see from here that it's not as black as asphalt.
You are not correct. The reflectivity of the Moon (known technically as the albedo) is indeed roughly that of asphalt or a blackboard. The Moon looks white because it is brightly lit in a dark sky. A piece of asphalt the same size as the Moon, at that distance, sitting in full sunlight would look the same.

Instead of guessing, you could research this. The information isn't hard to find. Try a web search on "moon albedo" and see what you get.

Quote:
Still the usually quoted surface tempreture range is +200 degrees F. in the sun and -200 degrees F. in the shade.
Again, this is misleading. The surface of the Moon does get hot, but not until the Sun is shining down on it at a steep angle. Try walking on your beach at an hour after sunrise and compare how hot the sand is to noon.

Anyway, the analogy is false; the reflectivity of metal is probably 3-5 times better than the Moonrocks.

Quote:
Also try touching a silvery chrome bumper in the sun just after noon, it's hot.
While chrome is highly reflective in the visible portions of the spectrum, I have read that it has a very low emissivity; that is, it traps heat very well. So while it does reflect efficiently, what it does not reflect it doesn't emit efficiently. The heat builds up, just more slowly (this too can be found on the web).

The lesson here is that your common sense may steer you in the wrong direction, as it has in this case. There may be (and almost certainly always will be) many factors of which you are unaware that profoundly affect the case you are studying.