Shadow of a rock

[lionking]

www.hq.nasa.gov/alsj/a14/as14-68-9486.jpg

Taking into consideration that
1- the iris of the camera is opened, as discussed in previous thread,
2 - that the ground is reflective
3- that the object is not dim

why does the rock completely obscured by the shadow while the astronaut and LM not, althaugh if you look at the surface of the rock, it is not that dim?

thnx

[dwight]

Polished metal is alot more reflective than a rock's surface, no? Notice the black areas of the LM are not brighter than the shaded areas of the rock.

[lionking]

dwight
look how the details of the rock here show clearly
www.spacearchive.net/img/AS16-107-17561.jpg

Look at the initial photo. The biggest rock's shade hides the rock, althaugh it is not dark, but as the rock above.


Also, look at the astronaut here www.hq.nasa.gov/alsj/a17/as17-146-22294.jpg

he is dimmer than the one in the initial photo, yet the dimmer grey rock shows more details than the white rock in the initial photo. So, dimmer astronaut and brighter rock vs. more lighted astronaut and dimmer shadows, althaugh brighter rocks.

[echnaton]

The photos will differ greatly depending on many factors, The position to the sun relative to the camera, the shutter speed, the materials reflective properties, the height of the object above the lunar surface, etc. Arbitrarily comparing different photos does not hold much promise in getting useful information.

[lionking]

O.K let's stay in the first photo.
look at the two tiny rocks that are close to the ground. They show no details. As for the reflective properties, rocks are rocks, and in this photo seem of similar color. Look at the biggest rock, it has a white rock attached to it that shows details, bcz it is facing light more, you would ay. But the LM should be in total shadow. Same for the astronaut.

Look at astronaut here www.masaakix.interlink.or.jp/apollo/d_apollo/apollo-16/_image/ap16-eva-plumcrater2.jpg

look at the white rock. He shows details, the rock next to the ground doesn't. Considering same camera exposure, white rock (althaugh a bit dimmer than the astronaut, but not to the extent that it shouldn't show any details). Besides, it's close r to the ground which would compensate its dimmer color, I suppose. Yet, it shows no details.

[AstroSmurf]

When taking a picture of the shadowed side of things, the sunlight that has been reflected from the lunar surface will illuminate them. The more of the surface that part of the object can "see", the brighter it will be lit, so the parts closer to the ground will normally be darker than the ones further up. The shape of the "facing" landscape may also affect it.

Additionally, note that an astronaut photographing up-sun (i.e. facing the sun) will work as a diffuse reflector, since his suit is highly reflective. So there actually is an extra "light source" in some of those pictures...

[lionking]

but the rock here rst.gsfc.nasa.gov/Sect19/i14-15.jpg
is fairly high, not lighted though
while its astronaut is fairly lighted

[nomuse]

You have to think in planes. Believe it or not, I can reconstruct that scene without having to take into account any material differences. To break it down into the simplest parts, those planes of the surface that face the sun are bright. Those that face away from the sun are dim. Those that face the sun at an angle are medium-lit. If you examine the rock, you will find that the dark areas are without exception tilted further away from direct sunlight than is the majority of the astronaut. Furthermore, if you look for areas on the rock that are facing directly out of the picture plane (as are the medium gray tones of the astronaut), you will observe a similar grey.

Use this as a mental model. Astronaut = cylinder. Rock = pyramid, with one corner facing the camera. Funny thing, but everything behind that corner is in shadow -- whereas, the only "corner" the astronaut has to create such a shadow is that of his PLSS.

But don't take my word for it. Take a rock's. Go find yourself some rocks and hold them up to a light...preferably a single light source, like a flashlight.

Of course this last pic is a bit small and over-compressed. A better version _would_ show some differences from the texture and lightness of the suit, and the effects of inter-object illumination.

[Apollo Gnomon]

lionking:

All this dancing around about planes and rocks and compressed images is just BS. I'm gonna tell you the real story. This is not without personal risk to me, but I don't care if they take away the company car, ruin my credit rating or put excess flouride in my water, I'm gonna tell the truth from now on.

I don't really want to be a paid debunker anymore, I'm quitting. The stupid pre-y2k computer that runs us says my post count is too low and won't release my check this month, so I had to pimp out my mom to pay the bar tab again and I'm bitter. Bitter like an English beer, I'm bitter. In fact, I'm mad as hell and I'm not gonna take it any more!

This picture and several others were discussed in a recent issue of "Moon Bunk'r," our secret newslettter. They were filming in an underground chamber made by nuclear weapons testing. The moon dirt is a mix of re-solidified melted rock, volcanic ash trucked in from Mexico, and several kinds of industrial waste products including shredded fiberglass insulation - hell on cameras and other equipment, but it looked prettty good on film.

Then it was decided to film in vacuum. So they pump the chamber full of vacuum, everybody is wearing a "space" suit, the suits don't work right, they're hot as hell and impede movement, everybody's cranky and mistakes got made. Plus, all the crew have strap-on booties to make their footprints look like craters and their knees and backs hurt.

Stanley Kubric should have been on the ball and caught the mistakes but he was busy arguing with the grips, who wanted a bigger share of the hush money because the gaffers were on strike and the grips were doing all the gaffing and gripping. So they didn't have the experience with the lights to know that the filaments overheat in a vacuum, and burn out more often. Bank after bank of the shadow in-fill lights had to be replaced, but they were under a tight schedule (rememeber - this is in a radioactive chamber, so they have to get in and out quickly) and several shots were taken with some of the lights burned out. The LM is bright because it's on the other side of the set where the lights were still working.

Only apollo 14 and 15 were filmed in this set. Apollo 11 was a real fly-by, with ground footage shot in Nevada on a smaller set; 12 was shot in several locations including a volcanic crater in Oaxaca, Mexico, and from 16 on they were filming at a set in Siberia, easier to keep cool. Canceling the later missions was part of a deal with Kruschev.

Apollo 13 actually landed on the moon. The astronauts were so sickened by radiation blasting up off the moon surface that they had to fake a damaged ship to the media, in case the astronauts didn't survive and they had to scuttle the mission.

Everyone here is going to deny this, but that's because they are either in on it or just dupes.

But you can believe me. I wouldn't lie to you. Because you're my friend.

[Retrograde]

gnomon said:

Canceling the later missions was part of a deal with Kruschev.

I can vouch for this part of the story.

[lionking]

Apollo Gnomon
truthful and you'll remain so. I always counted on you

nomuse
www.masaakix.interlink.or.jp/apollo/d_apollo/apollo-16/_image/ap16-eva-plumcrater2.jpg
astronaut here is not hit in planes by the sun. It is just behind him, (see shadows). No?
yet, he shows up lighted, but the rock not.

Now for the closeness of rocks to the ground: www.saharamet.com/desert/photos/Sahara.html

Notice the fourth photo where it says: Small erg, such dunes move on several meters each year.
Look at the mid dune. The dune is high, yet there is no difference in shadow dimness between the bottom and the top.

The NASA photo above shows a white rock, in dim shadow. A white astronaut lighted.

Another photo shows a dim astronaut in a dim shadow, while a second one shows him lit in a dim shadow.

[captain swoop]

ok so what do any of your observations prove? What are you driving at here?

Plus to sa 'a rock is a rick' is a bit general, rocks have different properties depending what they are made of!

[lionking]

I am saying that the astronaut was lit up bcz of some studio light. Rocks are white so they should show details

[captain swoop]

but that depends on the angle of the rock to the sunlight and the nature of its surface, u cant just say 'rock is rock'

[AstroSmurf]

And FYI, the rock was dark grey for the most part. "Powdered charcoal" is how Armstrong described the lunar dust, and yet it shows up pretty bright since the sunlight was so intense.