Re:Lunar Crater Radio Telescope on the Far-Side of the Moon ...
by Asraelite on Wednesday September 15, 2021 @01:22PM
(#28541839)
> 14 days out of 28
Out of 29 and a half actually.
I'm curious where the misconception that a lunar month is 28 days comes from. I believed it too but I can't find any good reason for doing so.
Re:Lunar Crater Radio Telescope on the Far-Side of the Moon ...
by credit_guy on Wednesday September 15, 2021 @02:27PM
(#28542552)
You are right, and I was just lazy. 28 is an even number, and it felt nicer to say 14 days out of 28, rather than 14.75 out of 29.5.
Separately though, the misconception comes from the fact that we have 4 phases of the Moon (new, first quarter, full, last quarter), and it's easy to conceptualize that the interval between two is 7 days, or one week, rather than 7.38264725.
Re:Lunar Crater Radio Telescope on the Far-Side of the Moon ...
by dave333 on Wednesday September 15, 2021 @05:14PM
(#28544445)
Sidereal month (relative to fixed stars) is 27.32 days.
Synodic month relative to Earth is 29.53.
There are other months that correct sidereal for motion around the sun, eccentricity of the lunar orbit, and tilt of lunar orbit, but the difference is tiny.
The changes in temperature are exaggerated. If you cover the telescope during day with some type of cover (like space blanket [1]), then everything that's not in direct light will stay at the same temperature as during the lunar night. For the simple reason that there's no air on the moon to transfer heat, and the regolith is a very good insulator.
So you could end up using the telescope 14 days out of 28 and be done with it.
But what's more, you can set up the space blanket to only protect the part of the telescope that's in direct sunlight. For the rest of the telescope it will appear like it's perfect night, because there's not atmosphere to disperse the rays of the sun. So you can end up using the telescope during the lunar day as well, although not at full exposure.
[1] https://en.wikipedia.org/wiki/Space_blanket