Author Topic: Colour difference between highland and mare  (Read 411 times)

Offline Peter B

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Colour difference between highland and mare
« on: January 22, 2024, 10:09:05 AM »
Hi folks

I was wondering if the Brains Trust could help me again, please.

A poster on YT has said that the surface of the Moon always looks the same shade of grey, regardless of mission; but images of the Moon as a whole show the highland areas as much lighter than the mares. Therefore, according to the poster, the surface of the Moon in the Apollo 16 photos should be much lighter than the surface of the Moon in the photos from the other missions.

I compared the ground colour in hi-res versions of AS11-40-5875 and AS16-113-18339*, and while I think the ground in A16 is slightly lighter than it is for A11, it's only a small difference.

Can anyone explain the reason why the colour difference wouldn't be more pronounced? Thank you!

* I chose those photos because they were photos taken of Aldrin and Young (a) in direct sunlight, so we could see their sunlit spacesuits, and (b) early in their (first) moonwalk, so their spacesuits hadn't got dirty yet.

Offline Allan F

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Re: Colour difference between highland and mare
« Reply #1 on: January 22, 2024, 10:11:54 AM »
Exposure. Either in-camera or in the reproduction of the photos. You can't really infer anything about the brightness unless you have the original negative/positive and the exposure information. Also, there is the issue of the retro-reflector properties of the surface, which alters the amount of reflected light dependent on the direction of the camera relative to the sun. If you shoot with the sun at your back, the regolith will appear much brighter and if you shoot across the sun, or even up-sun.
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