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Post by stabbogaz on Sept 6, 2006 9:16:23 GMT -4
All being well, this might shut the eejits up once and for all. ;D Compare these two photos : Look into the sky between the right hand pole & the rock on the horizon & tell me what you see. And what on earth is the blueish streak that moves up between the two above the right hand pole ?
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Post by gwiz on Sept 6, 2006 11:16:43 GMT -4
The fact that there are similar bright specks in the shadow on the left gives a clue to their nature.
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Post by sts60 on Sept 6, 2006 12:41:42 GMT -4
Does anybody know where there's an electronic version of the star images (pretty cruddy ones, really) taken by handheld camera from the CM on one of the later missions?
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Post by PhantomWolf on Sept 6, 2006 16:33:40 GMT -4
Look into the sky between the right hand pole & the rock on the horizon & tell me what you see.
Some dust on the scan I'm afraid.
And what on earth is the blueish streak that moves up between the two above the right hand pole ?
More dust, or possibly a hit by a cosmic ray, sorry to burst your bubble, but none of the marks are stars
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Post by freon on Sept 6, 2006 23:13:26 GMT -4
They didn't have cameras capable of taking pictures of those brilliantly lit stars in those days. Even though they had 3 to 4 days travel either way, it was not even a consideration. And with the rolling of the CM, they would have come out all blurry anyway.
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Post by LunarOrbit on Sept 6, 2006 23:47:56 GMT -4
it was not even a consideration. Why should it have been? They're the same stars we can see better from Earth's ground based telescopes.
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Post by grashtel on Sept 7, 2006 1:01:19 GMT -4
They didn't have cameras capable of taking pictures of those brilliantly lit stars in those days. Even though they had 3 to 4 days travel either way, it was not even a consideration. And with the rolling of the CM, they would have come out all blurry anyway. As LO said why would they? The viewing conditions in space aren't sufficiently better to make taking pictures with a small telescope worthwhile as the big ground based ones get better pictures. Carrying a big telescope on Apollo wouldn't have been practical as it would have been too big, too heavy, and too expensive to be a secondary part of the mission, and as Apollo's primary mission was studying the Moon couldn't be a primary part.
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Post by Kiwi on Sept 7, 2006 7:29:03 GMT -4
Stabbogaz: It is impossible to take a correctly-exposed picture of a normal sunlit scene and include stars in the same picture. Well, at least in the vicinity of Earth. Perhaps it could be done out near Jupiter or Saturn, but I haven't checked.
The simple reason is that a good exposure-setting for stars is at least 30,000 times more than that for a sunlit scene, and anyone who has an adjustable camera can easily prove this for themselves. Shoot some stars at the same exposure as for a sunlit scene and you won't get any stars on either film or pixels.
Here is the maths. A typical down-sun exposure with 100 ISO film is 1/250 at f11. The shortest exposure that will register the brightest stars is about 8 seconds at f2.8, but because of film's reciprocity failure during long exposures, 20 to 30 seconds at f2.8 is a better exposure.
Each step below doubles the exposure, and the increase over the sunlight exposure is shown.
1/250 @ f11 1/250 @ f8 ======= 2x 1/250 @ f5.6 ====== 4x 1/250 @ f4 ======= 8x 1/250 @ f2.8 ===== 16x 1/125 @ f2.8 ===== 32x 1/60 @ f2.8 ====== 64x 1/30 @ f2.8 ===== 128x 1/15 @ f2.8 ===== 256x 1/8 @ f2.8 ====== 512x 1/4 @ f2.8 ===== 1,024x 1/2 @ f2.8 ===== 2,048x 1 sec @ f2.8 === 4,096x 2 sec @ f2.8 === 8,192x 4 sec @ f2.8 == 16,384x 8 sec @ f2.8 == 32,768x 16 sec @ f2.8 = 65,536x 32 sec @ f2.8 = 131,072x
As you can see, 130,000 times is nearer the mark than 30,000 times. But don't take my word for it -- prove it to yourself. Take a well-exposed star picture and another of a sunlit scene and note the difference in exposure.
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Post by sts60 on Sept 7, 2006 12:40:18 GMT -4
They didn't have cameras capable of taking pictures of those brilliantly lit stars in those days.
Well, since stars are somewhat brighter when seen from above the atmosphere (though not that much brighter - we've crunched the numbers on one of the stargazer threads), and cameras could take pictures of the stars from the ground, that doesn't really make any sense.
Even though they had 3 to 4 days travel either way, it was not even a consideration.
As others have said, what would have been the point? The celestial sphere doesn't change on such a short trip, and any camera which could have been carried on Apollo could have been outdone by a reasonably-well-equipped amateur.
And with the rolling of the CM, they would have come out all blurry anyway.
If I recall the photograph correctly, there was some trailing. But the CSM wasn't always in PTC roll. Anyway, I said it was a pretty cruddy picture.
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Post by Jason Thompson on Sept 8, 2006 7:59:59 GMT -4
It is impossible to take a correctly-exposed picture of a normal sunlit scene and include stars in the same picture. Well, at least in the vicinity of Earth. Perhaps it could be done out near Jupiter or Saturn, but I haven't checked.
The complete lack of stars in the many images from Hubble and planetary probes of the outer planets suggest that even here it is not possible.
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Post by orumdude on Sept 9, 2006 9:40:17 GMT -4
They look like stars to me. Of course the people on this forum are so clever they can tell dust on a camera lens just by looking at a picture. I'm sure they must be qualified in some way.
The sight of the sky outside the earth's atmosphere would have been stupendous but that would have given the game away completely because the planets would have been expected in some of the pictures too and they would be in small but noticably different positions particularly Mars and Venus. Even Bill Gates would have taken a picture of the stars from the moon.
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Post by Data Cable on Sept 9, 2006 11:49:37 GMT -4
the planets would have been expected in some of the pictures too and they would be in small but noticably different positions particularly Mars and Venus. Why?
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Post by echnaton on Sept 9, 2006 12:07:47 GMT -4
The sight of the sky outside the earth's atmosphere would have been stupendous
The sight to an astronaut is largely irrelevant. The pertinent questions are,
1) how much brighter are the stars when viewed from above the atmosphere? 2) Is it possible to photograph stars at the same time as properly exposed sunlit objects? Answer these questions.
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Post by orumdude on Sept 9, 2006 12:12:31 GMT -4
The sight of the sky outside the earth's atmosphere would have been stupendousThe sight to an astronaut is largely irrelevant. The pertinent questions are, 1) how much brighter are the stars when viewed from above the atmosphere? 2) Is it possible to photograph stars at the same time as properly exposed sunlit objects? Answer these questions. They are much clearer, see Hubble 2) No it isn't but they could have taken pictures with the correct equipment. pointing it at the stars.
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Post by grashtel on Sept 9, 2006 14:22:04 GMT -4
They are much clearer, see Hubble Only about two to three times as clear, important for a major telescope like Hubble, not significant for anything Apollo could have practically carried. Consider this, if the viewing conditions in space are so much better why doesn't every space mission take advantage of them to snap a few reels of the stars? Apollo's primary mission was to study the Moon, carrying a telescope big enough to take advantage of the better viewing conditions in space would have severely compromised that mission (for visible light observations anyway), even assuming that 1960s technology was even able to build a major telescope that could survive the stresses of launch without being too heavy to be practically launched at all. Also Apollo did take pictures of stars, 16 had a small ultraviolet telescope that was used on the surface of the Moon. As to why they used an ultraviolet one rather than a visible one, that is because ultraviolet observations are not possible from the surface due to the atmosphere blocking most UV light.
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