[ExI] Fermi question

[BillK]

On Sat, Dec 31, 2011 at 8:41 AM, Kelly Anderson wrote:
> I am perfectly willing to accept that you can't see man made
> structures from space without a lot of magnification even from low
> earth orbit. My question has shifted to whether or not you can see the
> city lights from the moon, because you can CLEARLY, EASILY see them
> from LEO...
>
>

I think this might be a case of 'in theory, maybe - but in practice, no'.
The Apollo moon mission astronauts never reported seeing city lights
and the famous photos don't show any city lights.
See:
<http://nssdcftp.gsfc.nasa.gov/photo_gallery/hi-res/planetary/earth/apollo08_earthrise.tiff>

The reason for this is glare from the sun. The astronauts were
standing in bright sunlight, so their sun visors were probably down
and their eyes adjusted to the glare. So they couldn't see the
possible specks of light from cities. And you have to be on the
sun-side of the moon in order to see the earth.

Note that the photo above doesn't show any lights on the dark part of
the earth. But the photo doesn't show any stars either, so the camera
probably also had to have a dark filter over the lens to produce a
reasonable picture.

So the jury is still out on whether you could arrange the
circumstances just right so as to see the specks of light from earth
cities. You'll have to go there and try it for yourself.  :)


BillK