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  Earthshine visibility and the near side of the moon

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Author Topic:   Earthshine visibility and the near side of the moon
Max Q
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Posts: 391
From: Whyalla South Australia
Registered: Mar 2007

posted 01-07-2014 07:41 AM     Click Here to See the Profile for Max Q   Click Here to Email Max Q     Edit/Delete Message   Reply w/Quote
I am reading James Michener's "Space". The question was asked of Apollo 18 from Houston can you see any evidence of the previous landings.

This led me to think if the far side of the Moon was fully lit how much visibility would there be from orbit? I am thinking reflected light from the Earth.

LM1
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From: New York, NY USA
Registered: Oct 2010

posted 01-07-2014 10:49 AM     Click Here to See the Profile for LM1   Click Here to Email LM1     Edit/Delete Message   Reply w/Quote
The far side of the moon was first viewed by human eyes during the Apollo 8 mission. Apparently, it is not totally dark and craters can be seen (more here).

Max Q
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Posts: 391
From: Whyalla South Australia
Registered: Mar 2007

posted 01-07-2014 09:10 PM     Click Here to See the Profile for Max Q   Click Here to Email Max Q     Edit/Delete Message   Reply w/Quote
Thanks for that but I was meaning to ask how much visibility would there be from orbit of the near side if from reflected earth shine.

Robert Pearlman
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From: Houston, TX
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posted 01-07-2014 09:21 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
If I understand your question correctly, you're asking how visible the lunar surface would be from lunar orbit during a new moon as viewed from Earth. Correct?

Max Q
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From: Whyalla South Australia
Registered: Mar 2007

posted 01-07-2014 11:47 PM     Click Here to See the Profile for Max Q   Click Here to Email Max Q     Edit/Delete Message   Reply w/Quote
Correct.

LM1
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From: New York, NY USA
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posted 01-08-2014 08:55 AM     Click Here to See the Profile for LM1   Click Here to Email LM1     Edit/Delete Message   Reply w/Quote
If you are speaking about the NEAR side of the moon (although you mentioned the FAR side), I don't believe that astronauts in orbit around the moon can see any objects from previous flights on the moon. Satellites in orbit around the moon have seen such objects because the satellites have high-resolution cameras.

Max Q
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Posts: 391
From: Whyalla South Australia
Registered: Mar 2007

posted 01-08-2014 05:00 PM     Click Here to See the Profile for Max Q   Click Here to Email Max Q     Edit/Delete Message   Reply w/Quote
I'm sorry for the confusion, I was attempting to ask how much effect reflected earthshine has on near side visibility (if the reflected light from Earth was the only light source available). What would an astronaut be able to see from lunar orbit?

Skytrotter
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From: Indianapolis, IN USA
Registered: Sep 2013

posted 01-09-2014 07:09 AM     Click Here to See the Profile for Skytrotter   Click Here to Email Skytrotter     Edit/Delete Message   Reply w/Quote
From somewhere I remember that the light from a full earth as seen from the moon is about 16 times brighter than a full moon is as seen from the earth. If one flies in a plane at night during a full moon, it is quite easy to see details on the ground, so the surface of the near side of the moon should be quite visible under earth shine.

An even more direct way to prove this is to go out and look at the moon the next time it's a thin crescent. It is easy to see the earth shine and with binoculars one can see a fair amount of lunar detail.

So if someone were living on the moon's near side, it would never get very dark, either you would have bright sunlight or a fair amount of reflected sunlight from the earth. I guess it would only get really dark if you were on the lunar surface during a total lunar eclipse, it would appear as a total solar eclipse as seen from the lunar surface. Even then, the earth's atmosphere would refract a fair amount of the sunlight around the limb of the earth. If you have ever watched a total lunar eclipse, it usually has a dark red/orange color, so you could still see well enough to walk around on the lunar surface.

Max Q
Member

Posts: 391
From: Whyalla South Australia
Registered: Mar 2007

posted 01-10-2014 04:01 AM     Click Here to See the Profile for Max Q   Click Here to Email Max Q     Edit/Delete Message   Reply w/Quote
Awesome. Thank you Skytrotter.

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