The Moon and Sun Light

I'm no expert, but my curiosity was tweaked tonight.

Looking up at the moon (a full moon) I had one of those moments of clarity; the sun light makes the moon glow white in the sky.

Now, the question is:

As far as we know, as ATS users, how bright would the sun light be on the moon? It makes sense to me that it would be absolutely blinding.

If it is, does that mean they use filters when they photograph or video-tape the moon?

Thanks in advance.

The sun would appear brighter on the moon than on Earth, since the moon has no atmosphere to diffuse the light. As for filters, I'm not sure who the 'they' you're referring to are, but yes, there are special lunar filters available for telescopes and cameras and whatnot.

a reply to: Unrealised

I understand that it would be a similar brightness, but it will appear much whiter and brighter due to no scatter from an atmosphere.

I just read HERE that only 3% of the sun light is reflected to us.

Apparently, as a side note, the surface of the moon is quite black.

originally posted by: AdmireTheDistance
not sure who the 'they' you're referring to are, but yes, there are special lunar filters available for telescopes and cameras and whatnot.

The 'they' I am referring to is anybody who has been to or on the moon, and photographed it.

If indeed it has ever happened.

originally posted by: Chadwickus
a reply to: Unrealised

I understand that it would be a similar brightness, but it will appear much whiter and brighter due to no scatter from an atmosphere.

So basically, you'd need some serious eye protection to save you going blind?

originally posted by: Unrealised

originally posted by: AdmireTheDistance
not sure who the 'they' you're referring to are, but yes, there are special lunar filters available for telescopes and cameras and whatnot.

The 'they' I am referring to is anybody who has been to or on the moon, and photographed it.

If indeed it has ever happened.

Yes, we've been to the moon. Here is some good info about the Hasselblad cameras used on the Apollo missions.

Yes, we've been to the moon. Here is some good info about the Hasselblad cameras used on the Apologies missions.

Excellent.

I'll check it out.

a reply to: Unrealised

Some more info:
www.lpi.usra.edu...
sterileeye.com...

There are some members here who are far, far more knowledgeable about lunar photography (both of and on the moon) than I ever will be, but those links will at least give you some basic information.

a reply to: Unrealised

I'd imagine so, the visors used on the Apollo missions were pretty much like two way mirrors.

originally posted by: Chadwickus
a reply to: Unrealised

I'd imagine so, the visors used on the Apollo missions were pretty much like two way mirrors.

It just boggles my mind to think how absolutely blinding our area of space truly is.

To look out into the void and see a monstrous, blinding sun that we on Earth have never witnessed, would humble me to the core.

a reply to: Unrealised

I don't think it would be that monstrous, though. On a surface with a high albedo (such as the moon ), I imagine it would be quite bright, but I would think without the diffusing effect of our atmosphere, the sun itself would be little more than an incredibly bright spot. I may well be mistaken on that, though lol.

And I agree, viewing pretty much anything from space would be unbelievably humbling.

The moon gets lit up pretty good by "earthshine"



Image by me.

a reply to: eriktheawful

That's an excellent picture!


Edit: Like the Earth, I get lit up pretty good by moonshine...*badum tssss*

originally posted by: Unrealised

originally posted by: Chadwickus
a reply to: Unrealised

I understand that it would be a similar brightness, but it will appear much whiter and brighter due to no scatter from an atmosphere.

So basically, you'd need some serious eye protection to save you going blind?

The Moon's albedo is about 0.12. That is to say that 12% of the sunlight shining on the moon would reflect back up to a person standing on the moon (that intensity lessens by the inverse square law as an observer gets farther from the surface).

Moon Albedo

I can't find the source now, but I read somewhere that the light on the Moon is similar to the light reflecting off of an old asphalt car park on a sunny day. And that's old asphalt (more grey); new asphalt would be darker.


Plus, as has been mentioned, the intensity of the sunlight reaching the Moon's surface would be brighter than on Earth to begin with because Earth's atmosphere scatters the light somewhat. The Apollo astronauts had visor filters, and they made an effort not to point the cameras toward the Sun. This images that do include the sun are all awash in sun glare.

The central question is, how much brighter is the sunlight on the Moon compared to sunlight on the Earth?

To put it another way, how much light does our atmosphere block?

We don't need to google this or trust any agency for this information. We can find out for ourselves by performing a simple experiment (no special equipment required):

If we look straight-up from the surface of the Earth, we are looking through "one thickness" of the Earth's atmosphere. If we look at the sky at a slant (non-vertical) angle, we are looking through a greater thickness of the Earth's atmosphere. Using a little trig, we find that if we look up at ~30 degrees (1/3 of the way from the horizon to straight overhead), we are looking through "two thicknesses" of the Earth's atmosphere.

Thus, the difference in atmospheric effects from 30 degrees to 90 degrees is the same as the difference between looking at 90 degrees through the atmosphere and looking through no atmosphere at all.

So if the atmosphere were absorbing/scattering more than 90% of the incoming light, then the Sun, Moon and stars would be more than 10 times as bright when straight-up as compared to when they are one-third of the way to the zenith. We can see with our own unaided that this is not the case. In fact, we can see that objects straight-up are less than twice as bright, therefore we know the atmosphere absorbs/scatters less than 50% of incoming light.

Of course, since the International Space Station is also above the atmosphere and the same average distance from the Sun that the Moon is, sunlight on the ISS is just as bright as on the surface of the Moon. In fact the ISS gets more reflected light, since the Earth's albedo is ~3 times that of the Moon. This is graphically illustrated in this video. At 00:16 seconds you can see the sunlit side of the Moon superimposed on the Sahara Desert. The lunar regolith is much darker:

Sunlight outside the Earth's atmosphere is pretty blinding. Even the ISS astronauts commented on this, in terms of getting a quick suntan when looking out of the Cupola module, or in terms of photography: time.com...

Exo-atmospheric is really, really bright. You know the sunny 16 rule, which is F16 at one over the ISO for a shutter speed? If you follow that rule, you basically can’t go wrong for standing outside in the summertime with a nice sunlit scene. The sunny 16 rule applies to being in orbit, but you have to stop down two more stops because it’s a lot brighter. So that’s an example: Being exo-atmospheric, the sun is a lot brighter.

It's pretty blinding reflected back to Earth if you look through a telescope!

One of the experiments carried out by Apollo was 'dim light' photography in Earthshine. Photographing lunar features in shadow is much more useful for determining surface relief than bright light.

This Apollo 16 image for example:



from

tothemoon.ser.asu.edu...-127-20018

was taken near the moon's western limb with it well in shadow, lit solely by reflected light from Earth.

originally posted by: Unrealised
Now, the question is:

As far as we know, as ATS users, how bright would the sun light be on the moon? It makes sense to me that it would be absolutely blinding.

Think of weathered asphalt under direct sunlight. You'd still want to wear your sunglasses, because it would be very bright.

If it is, does that mean they use filters when they photograph or video-tape the moon?

Thing with photographing or filming, is that the camera can (and will, if you use automatic settings) use appropriate exposure and aperture for the lighting conditions at hand. Thus, when the Moon fills most (or all) of the frame, the camera will adjust for the Moon's brightness. When looking at the Moon through a telescope, it's advised to use the "moon filter" which will dampen some of that brightness.

So, on the one hand, the Moon is pretty dark (graphite-grey, asphalt-grey), but is illuminated by the blindlingly-white sunlight.

originally posted by: wildespace
Exo-atmospheric is really, really bright. You know the sunny 16 rule, which is F16 at one over the ISO for a shutter speed? If you follow that rule, you basically can’t go wrong for standing outside in the summertime with a nice sunlit scene. The sunny 16 rule applies to being in orbit, but you have to stop down two more stops because it’s a lot brighter. So that’s an example: Being exo-atmospheric, the sun is a lot brighter.

So why did they use a "Looney 11" settings? Being a lot brighter they should have been using Looney 22?
i.imgur.com...