[ExI] Fermi question

[Kelly Anderson]

On Sat, Dec 24, 2011 at 8:45 AM, Ben Zaiboc <bbenzai at yahoo.com> wrote:
> Kelly Anderson <kellycoinguy at gmail.com> asked:
>
>>On Thu, Dec 22, 2011 at 5:49 AM, Ben Zaiboc <bbenzai at yahoo.com> wrote:
>>>
>>> The idea of the Great Wall of China being visible from space pre-dates space travel. ?It was /expected/ to be visible from space, but in fact isn't.
>>>
>>> It's too similar to its surroundings to stand out, which is why far smaller structures are visible from orbit, but the wall isn't. ?Apparently, from the Moon, absolutely nothing man-made is visible on the earth.
>>>
>>
>>Can't you see the big lighted cities at night from the moon??? Seems
>>like seeing LA all lighted up wouldn't be that hard. Of course that
>>isn't really a "structure"...
>
>
> Well, I was just reporting what people who've actually been there have said.  I don't know if any of the moon landings took place when the night-side of earth was visible, so maybe they just didn't have a chance to see.  Interesting quesion though.  Even the biggest urban sprawls would be a tiny pin-prick from quarter of a million miles away, and street lights are pretty dim, so maybe not.
>

In this video from 18 to 20 seconds, you can see some lights on the
earth that appear to be city lights, but it's hard to tell at the
YouTube resolution.
http://www.youtube.com/watch?v=6VdSFT8Ouqg&feature=player_embedded

I suspect this is at a distance more or less analogous to the distance
from the moon... so the answer would seem to be that if you were on
the moon during a solar eclipse, you could indeed see city lights...
but I don't know for sure.

-Kelly