reply to post by Arbitrageur
Hi Arbitrageur, thanks for taking the time to look at that site.
What I am thinking here is that the fact that in telescope mode, and with a super-fast film, they needed such long exposures to image the heavens.
That they could do such long exposures before any image blur occurred shows, to me, what a good place the Moon would be for astronomy, but yes, the
new space based 'telescopes' probably negated the need for a Lunar astronomy base.
Anyway, when they switch to spectrographic mode, the heavens light up. They are looking at a Balmer line of hydrogen, and that is what the partial
shell around Earth is, but it is not, as Exponent seems to think, because the gas is at over 6000 degrees. All gases though will emit at different
wavelengths at certain voltages, as can be seen with spectrum tubes.
Nearly all present day astronomy is now performed by spectrogaphic means, and they use filter wheels to try and pin down what the 'light' is from,
but Hydrogen being the most common element, it is the most important. The 'light' in this case is actually a continuum, billions of little lights if
you like, which means they are looking at what is a point source array, in which case the 'light' will be emitted as a planewave, or
quasi-planewave, which is capable of travelling almost infinite distances with no loss of intensity, while the transverse EM wave, the type of light
our eyes can see, falls off with the inverse square rule.
This explanation on this page is probably very, very close to a proper explanation:
Abolishing the wave-particle duality nonsense
Most 'light' I believe is travelling in the vacuum as planewaves, which our eyes can not see, at any wavelength. It requires gratings to convert the
wave fronts to the transverse EM our eyes, or a regular camera that mimics our eyes can see, but in the case of being able to see stars from Earth, it
is the ionosphere which provides the method of creating the transverse waves. So, as to why the moon is so dark, it is because the Sun does not shine
on, or reflect off of the Moons surface. The light they there is produced by solar EUV/UV interaction with mainly electrons in the Lunar ionosphere.
They say it is Earthshine, and it is in a way, but it is really from the UV planewaves produced in our ionosphere interacting in the Moons ionosphere
to create a similar effect to Earth glow. So, no direct sunlight hits the Moon, or any other planets surface, that's why the light levels are so low.
They can not see the Moon from the ISS if they could look at it in a direction perpendicular to Earths surface, as the ionosphere is too thin up there
for the conversion process to work, they have to catch it when it is passing through the Earths ionosphere, just above a crescent Earth. NASA can not
prove me wrong, and won't even try.