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From: (Henry Spencer)
Subject: Re: Solar panels "Bright new star" ?
Date: Sat, 2 Dec 2000 18:21:55 GMT

In article <V8aW5.38481$>,
John M. Darnielle <> wrote:
>  The Moon looks pretty bright even
>> though its surface is actually as black as coal (!)...
>Huh? I've seen coal, and I've seen lunar rocks, and I'm sure that one was
>black and one was grey (dark grey to light grey, but grey)

You've seen *cleaned* lunar rocks.  Here's what Don Wilhelms (a planetary
geologist) had to say about the opening of the Apollo 11 sample boxes, in
his "To A Rocky Moon":

  After what seemed like an eternity, the first box was opened at 3:49 PM.
  Then the first Teflon bag was slit open.  All eyes focused on what looked
  like: the Rosetta Stone? primordial chondrites? sparkling pegmatites?
  No; dirty coal.  Astronomers had been saying that the Moon is really dark
  and not off-white as it seems in the night sky, and obviously they were

The appearance of those first rocks has also been compared to badly burnt

>My understanding
>is that the moon is as bright as it is because of the high concentration of
>titanium dioxide in it's soil, the same pigment that makes white paint

While there is a bit more titanium dioxide than is usual on Earth, it's
not in the highly-purified form used in paint.  The *brightest* lunar
soils reflect less than 25% of the light that hits them, and 5-10% is more

>...I just don't see how the moon's surfuce can be as "black as coal".

As I noted before, consider that when the Moon -- an object in bright
sunlight! -- is in the daylight sky, it's dim to the point of being almost
invisible.  Even coal will look bright if it's brilliantly lit against an
absolutely dark background.
When failure is not an option, success  |  Henry Spencer
can get expensive.   -- Peter Stibrany  |      (aka

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