Comment by 8bitsrule
11 hours ago
Very readable explanation of why and how useful a dark-side lunar radio telescope would be.
TLDR: As a result of expansion of the universe, over 13B years the wavelength of neutral hydrogen signals has been stretched from 21cm to 'tens of meters'. On Earth, this part of the spectrum is cluttered with noise from Earth and Sun. For 14 days at a time...not a problem on the dark-side.
It’s far side, not dark side. The moon doesn’t have a dark side anymore than the earth does
NASA uses "dark side" (meaning far side, not night side) when facing the public [0]:
> A series of test images shows the fully illuminated “dark side” of the Moon that is not visible from Earth.
> The far side of the Moon was first observed in 1959
[0] https://science.nasa.gov/earth/earth-observatory/the-dark-si...
> the fully illuminated “dark side”
Personally, I don't find the phrase 'fully illuminated “dark side”' to be a convincing alternative to the physically more accurate term 'far side'. Of course NASA has only just emerged from the Earth's dark side as I write this (UK here, mid-morning), so I'm not expecting an immediate response from them.
And yes, I do know that 'side' is itself not entirely accurate because of libration [0] but that's a different hill to die on.
[0] https://en.wikipedia.org/wiki/Libration#Lunar_libration
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