Kenneth nous apporta ses lumieres en ce 2005-12-24 02:56:
> Tim Riley <timothyrileyatnetscapedotnet> wrote:
> 
> 
>>I had to jump in here, even though I haven't been following the discussion
>>closely. The moon is illuminated by two sources: the sun and the earth. The
>>reflection of sunlight off of the earth (the albedo) is why we can see the
>>dark portion of the moon. The earth reflects approximately 39% of the
>>sunlight that hits it (which is where the title of Vangelis' album
>>"Albedo 0.39" comes from).
>>
> 
> 
> I had actually forgotten about that!  Thanks. But I seem to remember reading
> somwehere that the moon's surface material is VERY dark...which would
> explain why the "darK" part of the moon seems almost black, compared to
> it's much brighter half-moon shape.  In other words, the dark half is
> reflecting much less than 39%. Wheras, the sun is SO bright that it makes
> the moon's intrinsically-dark material positively GLOW with brilliance! ;-)
> So I would *assume* that the albedo isn't contributing very much to the
> bright half's appearance, relatively speaking.
> 
> Ken
> 
You're right. On the bright side of the moon, the earth's contribution can be
considered as 
negligeable, and practicaly ignored. You also need to consider the relative size and
the distance 
between the earth and the moon: if the earth was the size of a baseball and the moon
about that of a 
ping-pong ball, the distance separating them would be a little more than 2 meters,
reducing earth's 
contribution further.

-- 
Alain
-------------------------------------------------
When the bosses talk about improving productivity, they are never talking about
themselves.

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