Is the sun visible if you're standing on the moon..?

mfb

@trollcast: You have a typo in your moon distance (missing 0), but the values afterwards look correct.

A human head is ~20cm wide, I would expect something like ~40cm outer diameter for the helmets, and the ratio of earth size / helmet size in the image is something like 1:4. This gives a distance of ~3m for the photographer. Looks reasonable.

Try to take a photo of a human and the moon at night - you will note how small the moon appears from earth (even compared to earth as seen from moon). You usually see the moon somewhere in the night sky, without reference size - it just looks bigger that way.

Retroreflectors?


Below the images, the angle of the sun is shown - it is not extremely high, but they certainly landed when it was day.

enosis_

I never thought about it before - but the effect seems the same. If the sunlight is behind you on the moon - the illumination of objects is brilliant. If the sunlight is in front of you - it would be quite difficult to focus.

buzzdiamond

When I look up at the moon here from earth, the moon has a certain size. It may vary from time to time, but I have a good picture in my mind of how big it looks and/or how the smallest it will look. Based on the smallest the moon can look, if the earth is bigger than the moon (4x), then the earth will never look smaller in the sky when standing on the moon, then the moon looks standing on the earth. In the picture I referenced, the earth looks smaller in the sky than the moon does here on earth. That was my observation.

Saturday night, there was a program on TV showing video clips of the landing on the moon and the take off from the moon. I was watching very closely the takeoff. There was a camera on the lunar lander, with the flag in it view, just before takeoff. I'm not sure how thick the flag pole is or how deep it is in the moons surface. I don't think it would be very deep if it was only twisted into the ground by hand, or having said that, it would be planted very sturdy.

Now with the flag pole in view, you could also see footprints in the ground around the pole. As the lunar lander took off, there was much wind pressure from the engine to set the flag flapping wildly, as seen through the camera. Oddly enough, the pole did not bend or topple over. Also, the footprints did not disappear with large amounts of dust blowing up from the ground. As you can imagine, this seemed very odd to me, as I would expect to see something different than what I saw. I'm only stating what I saw on the video, which leaves me wondering, as well as others I would assume.

Having said that, since the flag pole did not topple over, and the flag was flapping wildly from the power of the engine thrust, would the flag still be flapping today..?

Drakkith

So? Again, you have no reference to compare the relative size of the Earth to. (Sorry, but a picture in your mind is NOT sufficient) How do you know whether it's apparent size is too small or not?

The footprints didn't get blown away because there is no air to do so. The exhaust is much too thin and isn't blowing correctly to do so. Any dirt that is loosed from the ground is NOT stopped by an atmosphere like it would be here on Earth. It simply flies up and outwards from the spot it is kicked up from. Since the footprints are not directly underneath the rocket they don't get erased. The flag was flapping because it is hanging loosely from the pole and can easily move around. That plus the ground isn't blocking the exhaust from impacting it. The force on the flag was enough to set it flapping, but not nearly enough to bend the pole. Remember that here on Earth a flag has to move air out of the way, effectively giving it "extra" mass.

No, it would lose energy as friction and such and stop.

russ_watters

Irrelevant. Next time you have a chance, take a photo of the moon with a normal camera and no zoom. You'll be shocked at how tiny it looks in the photo.

Chronos

I submit as evidence the Lunar Laser Ranging Experiment, which relies on mirrors placed on the surface of the moon.

Borek

Moon has a certain size because you are accustomed to watch it with your eye, that means always the same focal length. Try to take several pictures of some object with a Moon in the background with different zoom levels using any camera, and see how the ratio of their sizes change.

phinds

Chronos, anyone steeped enough in conspiracy nonsense to believe that men did not land on the moon is not going to be interested in actual evidence.

davenn

yeah exactly, they will just say it was left there by an unmanned mission

Dave

webtrekker

It was left there by an unmanned mission.

Actually, if the Moon is visible from the Moon then, by default, so must the Sun be!

mfb

Hmm... what is easier?

1) launch a big manned rocket, get in an orbit around moon, let them chat with earth a bit (the rocket was there, that was easy to track from earth). Develop an automatic system capable of landing several tons of mass on moon. Develop some robot to distribute various objects around the landing spot, including retroreflectors, flags, rovers and footprints. Let the system launch again (we have some hundred kg of rock from moon) and dock to the astronauts in orbit. Get everything back. Find some way to simulate moon-conditions on earth, film movies there. Find some way to keep a conspiracy involving at least 1000 humans secret.
2) Same as above just without the conspiracy, advanced robots and movies filmed on earth, simply let the astronauts enter that lander and do some tasks manually, including "walk on moon and leaving footprints".

Integral

Do not forget that a the time of the moon landings we were at the peak of the cold war. The Soviets were watching everything we did. You can bet that every radio transmission was monitored if there had been the even the slightest hint of trickery the Soviets would have been screaming bloody murder. To me the existence of a competing power attempting the same feat is the best assurance that we did indeed go to the moon.

phinds

Why are you guys trying to show that we went to the moon? Only conspiracy theory nut cases think we didn't and they have shown over and over that there is no amount of evidence and resonable discourse that is going to change their minds. You are just buying into their nonsense by even taking part in such an arguement.

webtrekker

'A little nonsense now and then is relished by the wisest men.' - Willy Wonka

SHISHKABOB

but what if the USSR was in on it too D:

enosis_

Funny stuff!

Vanadium 50

OK, enough with the moon landing conspiracy theories, and back to discussing the actual science.