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Post by sts60 on Jan 25, 2006 23:07:10 GMT -4
The answer was given by Kaysing IIRC.
Bill Kaysing, the technical writer? Who had no education in astronomy (or physics or engineering)? That Bill Kaysing?
They couldn't have simulated the (position of the) stars correctly. Every competent amateur astronomer would have figured out the scam.
You have it exactly backward. Star positions would be one of the easier things to simulate. Far easier than trying to simulate a large-scale, 1/6 G, vacuum, Sunlit lunar surface.
And please tell me, why didn't they bring a camera on a tripod and a telescope instead of hitting golf balls around?
1. Because the objective of Apollo was lunar science, not astrophotgraphy. 2. Your question is incorrect, anyway, because a UV telescope was used on Apollo 16. I thought you said you studied Apollo? 3. A UV telescope was of some value because of UV absorption by the Earth's atmosphere, but a visual-light camera or telescope would not have been. Anything Apollo could have carried to the Moon could not have taken much better pictures than a moderately advanced amateur astronomer could have from Earth.
On the other hand, a golf club and ball stunt, while not "useful", required very little mass and no time to setup.
I'm sorry but if you can't see the sheer and utter ridiculousness of NASA's stage performance I can't help you.
Have you ever participated in mission design, or trained astronauts, or had to mark up a flight plan? I have. But I must have missed the part where you listed your experience in spaceflight planning and operations, which might give your handwaving an air of authority.
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Post by PhantomWolf on Jan 25, 2006 23:20:12 GMT -4
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Post by sts60 on Jan 25, 2006 23:24:10 GMT -4
Given today's computers calculating powers they may have been able to do it. In 1969 they couldn't.
Nonsense. Star positions in terms of parallax are virtually indistuinguishable from the Moon as opposed to from the Earth. Nor do you have any idea how much computing power might be required to do the computations anyway.
No, an experienced hobby astronomer
The term is "amateur astronomer". Can't you get the simplest details right?
checking the positions of the stars of his favorite sign
Can't you tell the difference between an astronomer and an astrologer?
would have called the bluff it would have been impossible to draw them all correctly on a backdrop.
Why, exactly? And if you couldn't figure out where they should go, how could you figure out if they're not where they should go? Your argument contradicts itself.
Also their appearance would have been a problem.
Why, exactly?
Actually, I think in a way it would have been tough to get the stars consistently right in terms of presentation. But their theoretical positions in the sky, contrary to your handwaving, would not have been a problem.
But we are digressing again.
Time for the backpedal.
Whenever we look at one of NASA's or the so-called astronauts' claims, e.g. the visibility of the stars, we find them incorrect.
Handwaving your disbelief, and ignoring detailed explanations, is not the same thing as finding something incorrect.
How many lies have to be exposed before people see the fraud?
Apparently, an infinite number. We've exposed a lot of the lies (and just plain mistakes, to be charitable) you have dredged up from conspiracist web sites, but you seem unable to see the fraud perpretrated on you.
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Post by sts60 on Jan 25, 2006 23:28:25 GMT -4
They were able to fool people for some time about the appearance of the lunar surface, since nobody knew how it really looked.
Factually incorrect. Numerous U.S. and Russian probes had orbited, impacted, and landed on the Moon before Apollo. Other unmanned missions have orbited and imaged the Moon since Apollo, and returned fully consistent imagery.
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Post by nomuse on Jan 26, 2006 0:15:05 GMT -4
Heh. Think of Destination Moon. Chesley Bonestell's wonderful backdrops were quite convicing then. Quite unconvincing now. He got so much right, and he looked at the best data available (Mount Wilson photographs, also picking a specific crater for the landing so the Earth would be properly visible in the shots).
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jan 26, 2006 1:23:54 GMT -4
Given today's computers calculating powers they may have been able to do it. In 1969 they couldn't.Nonsense. Star positions in terms of parallax are virtually indistuinguishable from the Moon as opposed to from the Earth. Nor do you have any idea how much computing power might be required to do the computations anyway. I still haven't figured out whether Stargazer is claiming there would be a measurable stellar parallax between Earth and the Moon or not. I don't think he is, but if so, below are some numbers for you. The parallax of the nearest star, Proxima Centauri, is 0.76 arcseconds, and that is measured with a baseline of 2 AU. The Moon is only 0.0026 AU away, thus the parallax of the nearest star when moving from Earth to the Moon is only 0.00099". A parallax this small can't even be measured. So the positions of stars when observed from the Moon would appear identical to what we see from Earth. EDIT: I correct some mistakes in the above calculation, please see post #446 for an explanation.
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Post by Count Zero on Jan 26, 2006 1:54:38 GMT -4
So the positions of stars when observed from the Moon would appear identical to what we see from Earth. I worked out the maximum parallax of the next closest object to the Earth, namely Venus. Even at closest approach (Earth at perihelion, Venus at aphelion) the maximum parallax (Moon at apogee) would be only .6 degrees, which is ~1/4 of the diameter of the Earth seen in this picture. Of course, we wouldn't be able to see that, because we'd be looking straight into the Sun. Move Venus to a more favorable viewing angle, and the parallax drops to insignificance.
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Post by Count Zero on Jan 26, 2006 2:40:28 GMT -4
And btw. why didn't they just point one those TV-Cameras up to the sky, live for all the world to see. Or did I miss those too? Yes, you missed those too. Ed Fendell (the remote camera operator) looked up a lot, sometimes deliberately to look at the Earth or to track the ascent stage liftoff on Apollo 16 & 17, and sometimes accidentally - The Apollo 15 camera had problems with its tilt function. Need I remind you that the camera was set to view a sunlit landscape? Are you going to remind me that, without an atmosphere, the stars are brighter? Well, the sunlight on the landscape is going to be brighter for the same reason and by the exact same amount. So as the camera aperture stops down to compensate for that, it will continue to not see the stars. Let's talk camera exposure. The astronauts used ISO 160 film. If you wanted to photograph stars from the surface of the Earth with that film, you're going to have to open the aperture wide and expose the film for several seconds. Let's pick a number, say 10 seconds (in fact, it would take much longer: On the Gemini missions they were photographing stars above the atmosphere using exposures of up to two minutes). It's a ludicrously low number, but hey, let's be optimistic. Now then; you say that the stars as seen from the surface of the Moon are much brighter. Although you have been asked several times "how much brighter?" you have failed to answer.* Let's say they are twice as bright: You would still need to keep the shutter open for 5 seconds. Five times as bright? 2 seconds. Ten times as bright? 1 second. The astronauts shot all of their photographs at 1/250th of a second shutter speed, and they had the aperture stopped-down. The TV camera scanned each frame at 1/10 of a second and was also stopped-down. Even with the most wildly optimistic assumptions, it was flat-out impossible for the cameras shooting in daylight to see the stars. Go try it yourself - It'll take less time than it did for me to write this post. *On page 26 of this thread (reply#381, to be exact) I laid out a simple experiment, using no equipment, to find out just how much the atmosphere attenuates starlight. According to my calibrated eyeballs, it looks like roughly 20%. In other words, stars (and sunlight) on the Moon would look ~25% brighter than they do on Earth. I welcome other people's measurements.
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Post by nomuse on Jan 26, 2006 5:28:31 GMT -4
Nice work, Count. I'm pretty rusty in those calculations but that sure sounds like it's in the right ballpark. (I would'a guessed a few degrees, maybe. Nothing larger).
Something tells me Stargazer is going to move away from this line of enquiry, however. I have heart, though; this is the closest we've gotten yet to actually engaging him in discussion.
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Post by PhantomWolf on Jan 26, 2006 7:56:49 GMT -4
I would have thought it was less than 20%. Of course one of the problem with doing it the way you did is that dust and smoke tend to be lower and thus is thicker closer to the horizon and also any light pollution is going to be greater nearer the horizon as well.
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Post by Count Zero on Jan 26, 2006 8:23:18 GMT -4
If you assume that the layers of dust & smoke are uniform horizontally (look in every direction of azimuth), then the 30 degree elevation is still looking through twice the thickness as straight-up/90 degrees.
Light pollution can reduce the apparent brightness of stars nearer the horizon, but that biases the estimates to make the atmosphere a bit more "lossy" (say, 40% instead of 20%). This merely creates a worst-case estimate.
In case anyone was wondering, the curvature of the Earth is largely irrelevant to the calculation. 10 miles straight-up gets you above 90% of the atmosphere, and basically all of the crud. The 30-degree angle translates to a horizontal distance of 17.32 miles, or 15 nautical miles. This is 1/4 of one degree of curvature: half of the angular diameter of the Moon in the sky.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jan 26, 2006 9:30:28 GMT -4
The parallax of the nearest star, Proxima Centauri, is 0.76 arcseconds, and that is measured with a baseline of 1 AU. The Moon is only 0.0041 AU away, thus the parallax of the nearest star when moving from Earth to the Moon is only 0.0031". A parallax this small can't even be measured. I have a couple corrections to the above (I must have been tired and not thinking clearly when I wrote it). The baseline used to measure stellar parallax is not 1 AU, it is 2 AU. Furthermore, the Moon's distance from Earth is 0.0026 AU (I used a mix of units, km and miles, in my previous calculation). The result of these corrections is that the parallax of Proxima Centauri when going from Earth to the Moon is 0.00099 arcseconds. Of course we can calculate the angle directly knowing the actual measurements. Proxima Centauri is 4.22 light years away, or about 4X10^13 km. The distance to the Moon is about 385,000 km. The parallax is the arctangent of 1/2 the baseline divided by the distance to the star, p = arctan(0.5*385,000/4X10^13) = 0.000000275 deg = 0.00099"
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Post by Kiwi on Jan 26, 2006 10:06:13 GMT -4
And please tell me, why didn't they bring a camera on a tripod and a telescope... Stargazer, do you actually pay any attention and do any real research? Away back on page 3, post 30, I told you about the Apollo 16 camera and photographs and asked you some questions, because you had already made the ridiculous and untrue claim that photographs of stars were never taken from the lunar surface. I directed you to an early article about the photos that you could have sought out and found, just as I did.
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Post by sts60 on Jan 26, 2006 10:29:56 GMT -4
Good job, Bob and CountZero. Nice quantitative answers.
The human eye can detect individual stars down to about 6th magnitude. There are roughly 6,000 such stars visible from the Earth's surface. If we take CountZero's worst case estimate of 40% visible extinction in the atmosphere, the limiting magnitude from a point above the atmosphere, such as the surface of the Moon, is found by:
Apparent brightness (AB) on Earth = (1-0.4) AB on Moon AB Moon = AB Earth / 0.6 = 5/3 AB Earth So stars on the Moon will appear up to 5/3 (1.66...) brighter. One order of apparent visual magnitude corresponds to a difference of 2.512.
There are about 13,000 stars of apparent visual magnitude +6 to +7*. Since the atmospheric extinction worst-case is less than one order of magnitude, and there are more stars to the fainter end of the range than to the brighter end, we can take about half the number as a ball-park figure.
What that means is you could see, if you had thoroughly dark-adapted eyes (>20 minutes in darkness) and of course no scattered or reflected sunlight in your field of view, up to twice as many stars as you could see on Earth, something like 13,000+. But most of them would be the much more numerous faint stars. The brighter stars would stand out more; it would be a spectacular sight, even better than a dark night in the desert.
But it would still be a matter of degree, not a completely unprecedented experience (except for perhaps a lifelong city-dweller!) And the number of stars you could see, even using the worst-case value for atmospheric extinction, is far, far less than what stargazer claimed. His claim of "trillions" of stars is off by a factor of about one billion.
stargazer, do you retract that claim? If not, why not?
*source: Brian Marsden, The Amateur Astronomer's Handbook.
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Post by stargazer on Jan 26, 2006 11:06:58 GMT -4
Unfortunately the astronauts forgot to do this, either because they were to dumb or more probably because they never were on the moon. You claimed "trillions" before, which was egregiously wrong. Do we assume by "zillions" you retract that and simply assert "far more than they could have seen from anywhere on Earth"? Because that's still wrong. Ok, it seems I was a little imprecise concerning the number of stars, so I checked that. A man standing on the moon--if there ever were a way to survive in that searing radiation hell wearing such a ridiculous space suit--would be able to see exactly |4.3 Quintzillions - 1| stars... and then some. That's none of your business.
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