[ExI] Fermi question

[BillK]

On Sun, Jan 1, 2012 at 4:34 PM, Jeff Davis wrote:
> With all respect, wouldn't you easily be able to see the night-time
> lighting on the earth simply by shading the sun -- covering it from
> view?  Looking toward the night side of the earth implies that you are
> looking, in general, toward the sun.  Hold up a hand, cover the sun,
> and the "glare" is gone, no?  And from space, with no dust or
> atmosphere, there would be no secondary sources of glare, no?
>
> From the moon, there could be surface glare, but if the earth were
> high enough above the lunar horizon, that glare wouldn't effect one's
> view, and then as before you block out the sun.
>
>

Well, the Apollo astronauts didn't do that. Probably because it takes
20-30 minutes for human eyes to fully adjust to darkness and they
didn't have the spare time. Anyway, just blocking out the sun would
still leave your pupils contracted by the glare around you. You would
need at least need night-vision eyes to see the pin-pricks of light
from earth cities at the moon's distance.

NASA says you would need a telescope to see earth city lights, in this
article about viewing Earth eclipsing the Sun from he Moon.
<http://science.nasa.gov/science-news/science-at-nasa/2005/20apr_lunareclipse/>
Quote:
The disk is Earth with its nightside facing the Moon. You can see
moonlit clouds floating over Earth's dark oceans and continents. You
can also see a faintly glowing ring of light around the planet--that's
Earth's atmosphere with sunlight trickling through it. A telescope
would show you Earth's city lights, too. Beautiful.
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BillK