Christopher James Huff wrote:

> In article <408719ff$1@news.povray.org>,
>  Dan P <dan### [at] yahoocom> wrote:
> 
>>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." This site contains some albedos that illustrate 
>>your point:
> 
> Yes, I know. I mentioned this in some of the messages I posted 
> previously. Such as the one a couple steps up this thread posted in 
> response to one of your messages. Which you replied to. It'd help if you 
> read them first...

... perhaps I am misreading this message. Are you feeling threatened by 
my explanation of albedo, which is causing you to become confrontational?

> The Moon's albedo varies drastically with angle because of glass beads 
> in the regolith (surface debris formed by impacting bodies...lunar dirt, 
> basically) which tend to reflect light back in the direction it came 
> from. The apparent albedo from earth is usually closer to 7%, but it 
> reaches about 12% at full moon. It'd be interesting to simulate this in 
> POV...

I'd like to see that too!

>>The Earth is 21% brighter than the moon (as you've said), probably 
>>because of all the water on the surface and in the clouds. Venus is 43% 
>>brighter because it has a lot more clouds to reflect the light. Venus 
>>has been so bright to us that people have mistaken it for the light of 
>>an on-coming train!
> 
> Venus is also closer to the Sun, about 0.7 AU, which means it intercepts 
> twice as much sunlight. Approximating the Sun as a point source. ;-)

Well, true; the amount of light that hits a surface does not change its 
albedo, though, but I see your point; I shouldn't have used "brightness" 
there without saying "all things being equal".

 > Still, I think you'd have to be pretty confused to mistake it for a
 > train light.

Indeed. People get like that, though.
-- 
Respectfully,
Dan P
http://<broken link>

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