Albedo and reflected light from the moon

[Billahertz]

Hi all,

I'm looking for a way to calculate how much light is reflected from the surface, on the moon, and whether that light would be strong enough to be classed as a bright light source.

I have no idea where to start with this, but basically I'm trying to prove a Lunar Hoax Conspiracy Crackpot wrong. He is stating that the Lunar Surface is not bright enough to obscure human vision on the moon so Astronauts can't immediately see stars. Obviously this is rubbish as Apollo astronauts have testified such, but ideally I need to prove it with some hard science. Any help would be appreciated.

 

[tony873004]

It's his claim. Make him do the math.

The Lunar surface is about as bright as asphalt. Tell him to stand in a well-lit parking lot at night and observe stars. There's a reason amateur astronomers avoid such places. And no matter how well you light this parking lot, it's going to pale in comparison to sunlight.

Furthermore, the astronauts probably could see stars if they looked straight up so the horizon wasn't in their view. The problem that the hoax believers point out is that no stars appear in the pictures. Tell your friend to try to take pictures of stars, but leave the camera settings at what they would be for bright daylight pictures.

 

[russ_watters]

The moon washes out most of the stars in the sky when viewed from earth. It's a stupid claim he's made. Yeah - make him do the math. He won't believe your math anyway.

 

[Chronos]

The moon has no atmosphere so stars are always visible from its surface. Apollo photos generally do not show stars because the exposure times were optimized to capture images on the surface of the moon - which is very bright compared to background stars.

 

[russ_watters]

Your eyes work similar to a camera though, Chronos - your pupils constrict to optomize for the brightness of the surface of the moon, making the stars invisible.

 

[DaveC426913]

He is stating that the Lunar Surface is not bright enough to obscure human vision on the moon so Astronauts can't immediately see stars.

Sorry, can you clarify? I'm trying not to make assumptions about your specific situation.

Your friend is claiming that the Moon's surface is not bright enough, and he is further claiming that because of this, astronauts should? or should not? be able to see stars?

It sounds like your friend is saying astronauts should be able to see stars, despite the reflection from the lunar surface. Yes?

 

[DaveC426913]

In answer to your question though, the Moon's albedo is 7%. It reflects about 7% of sunlight - quite low, relatively. Nonetheless, that's still a lot of unfiltered light.

 

[russ_watters]

In answer to your question though, the Moon's albedo is 7%. It reflects about 7% of sunlight - quite low, relatively. Nonetheless, that's still a lot of unfiltered light.

When I was in high school, there was a solar eclipse that covered 96% of the sun. It created an odd sort of twilight, but it was still bright enough to read by and there were no stars visible.

 

[DaveC426913]

When I was in high school, there was a solar eclipse that covered 96% of the sun. It created an odd sort of twilight, but it was still bright enough to read by and there were no stars visible.

Russ, I'm surrpised at you. :grumpy:

The big mistake MH'ers often make is thinking that they can work by analogy. "If it works here on Earth, it should work on the Moon."

The Earth in eclipse has no comparison to the Moon. No planet with an atmosphere can serve as an analogy to phenomena on an airless Moon.