Among other things, Dan P wrote:

>> The moon reflects light from many points
>> on its sunlit surface.  At the distance from it of Earth, the inverse
>> square law approximates the falloff pretty well, but nearer the surface,
>> most of the surface area is hidden, and you can only be really near a
>> small area, unlike a true point source where all light comes from a
>> single point. Yes, the earth only intercepts a small portion of the
>> reflected light, but the moon reflects a lot of light. Haven't you ever
>> been outside on a night with a full moon?
> 
> What you are describing is called the "albedo" of an object. This
> website[1] defines albedo as, "the fraction of light that is reflected
> by a body or surface."

There are different factors: the albedo, the apparent size, the distance to 
the sun (or the apparent size of the sun as seen from the body)...

The body gets some light -> distance from the sun
The body reflects some of this light -> albedo
The observer sees a fraction of this light -> apparent size
... and there might be some losses in between due to cosmic dust, atmosphere 
interaction, etc.

> Venus
> has been so bright to us that people have mistaken it for the light of
> an on-coming train!

It may be seen in daylight (if you know exactly where to find it), and on a 
night without moon, it can cast shadows.

-- 
light_source{9+9*x,1}camera{orthographic look_at(1-y)/4angle 30location
9/4-z*4}light_source{-9*z,1}union{box{.9-z.1+x clipped_by{plane{2+y-4*x
0}}}box{z-y-.1.1+z}box{-.1.1+x}box{.1z-.1}pigment{rgb<.8.2,1>}}//Jellby

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