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Looking at stuff on the moon: an analogy - The online computery journal thingy of a turtle

Jan. 1st, 2009

02:04 pm - Looking at stuff on the moon: an analogy

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Some people have wondered why we can't simply prove to the moon hoax conspiracy crowd that we've been to the moon, by pointing a telescope at the moon and photographing the artifacts left there by the Apollo missions: the LEM landing gear, the flag, the moon rover, and so on.

The simple answer is that we don't have a telescope powerful enough. This strikes some people as counterintuitive; we can see stars and nebulas millions of light-years away, can't we? But it's not how far away the thing is, it's how much of the visual field it covers. And the Apollo detritus is just way too small.

I'm trying to think of a good analogy to explain this. Here's what I've got so far:

Imagine you're standing on an observation point at the top of a hill at night. You can see the lights of a distant city. Maybe you can even identify some; for instance, that blinking red blob is the casino on Main Street, or that purple dot is the movie theater.

Now look down at your thumb. There are bacteria crawling around on your skin. Can you see them?

The city lights are the stars, your thumb is the moon, and the bacteria are the astronaut artifacts.

What do you think?

Comments:

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From:vakkotaur
Date:January 1st, 2009 08:25 pm (UTC)
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That's about right. The problem isn't faintness of light (in fact there are neutral density lunar filters so that looking at the moon with a telescope isn't so blinding), but a matter of resolving such a tiny image.

Or consider the difference between seeing the far off lights and being able to read the too fine print on a poorly designed bumper sticker.
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From:aerofox
Date:January 1st, 2009 08:35 pm (UTC)
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Japan recently put a satellite in orbit around the moon with a HDTV camera. I was hoping that it could see the artifacts, but apparently, it can't :(

this seems odd to me as it is so close!!!
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From:kinkyturtle
Date:January 1st, 2009 09:07 pm (UTC)
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That stuff on the moon is Just Too Small.
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From:orv
Date:January 2nd, 2009 12:25 am (UTC)
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This is also why the old conspiracy theory about being able to read license plates with spy satellites is fiction. (Well, and also because license plates don't face upwards.)

People overestimate the resolution of spy satellites, partly because of what they see on Google Earth. What they don't realize is that the really high-res images on Google Earth are taken from airplanes, not satellites.
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From:kinkyturtle
Date:January 2nd, 2009 01:27 am (UTC)
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Yeah, you'd think people would pick up on what's happening when they zoom in and see the blobby greenish images give way to sharp grayish images. Think, people, THINK!
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From:krinndnz
Date:January 1st, 2009 09:29 pm (UTC)
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I like the explanation from the Bad Astronomy dude. Very similar to yours, though: good ideas have this tendency to crop up independently.
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From:vakkotaur
Date:January 1st, 2009 09:54 pm (UTC)
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And I see this just after I work out the problem for myself.

Since the biggest thing left behind is the lunar lander itself, and using the landing gear span (the biggest distance) that's just over 9 meters. And the moon is on average 384,403 km away from the earth, a bit of trig and fiddling about gives 0.0005 (rounding up) arc seconds. So to detect that (not image it, merely detect as a fuzzy blob) would require a telescope with a primary of 2400 cm, or about 945 inches.

And that ignores atmospheric effects, that the earth-moon distance is rarely the average, and that the result is only enough to say "Hey, we found a blob where we think a blob ought to be." and not a nice pretty overhead view of an Apollo Lunar Module.
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From:maxgoof
Date:January 1st, 2009 10:23 pm (UTC)
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What is odd is that the astronauts left a corner reflector up there. That can be detected, easily, unfortunately, it does not reveal it's location very well, as there is still a spread that occurs.

Lunar landing deniers claim that it was put up there by an unmanned probe.
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From:thecanuckguy
Date:January 2nd, 2009 12:20 am (UTC)
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That's because WE DIDN'T REALLY LAND ON THE MOON! IT'S ALL A HOAX! IT WAS A SOUND STAGE INSTEAD, YOU CAN HEAR THE TECHNICIANS IN THE BACKGROUND!!!!!

... ahem ...

uhh, yeah, where was I?

Could it be analogous to the fact that we can't make out many fine objects (like, for example, people) in Google Earth? Especially if we zoomed out to a level that simply shows, say, just your city?
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From:nefaria
Date:January 2nd, 2009 12:29 am (UTC)
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Aaaaahhhhh!!! Thumb bacteria!

**douses you head to toe with hand santizier**
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From:kinkyturtle
Date:January 2nd, 2009 01:28 am (UTC)
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Yeah. My little analogy is mainly meant not for conspiracy nuts, but for average people who want to help discredit the conspiracy nuts and wonder why we don't just point the Hubble at the moon.
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From:deckardcanine
Date:January 2nd, 2009 02:26 am (UTC)
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Even if we could get images as clear as a typical National Geographic nature photo, there'd be the difficulty of positioning the telescope exactly right. How long would we have to sweep it around the surface of the moon before we found the landing site again? You'd have to move the scope very slowly, too.
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From:gedrean
Date:January 7th, 2009 12:26 am (UTC)
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There was a Mythbusters where they went to an observatory.
Long story short we put a reflector on the moon, about human-sized-tall. They point a laser at the moon.
They fire it. It shoots the light right back into a receptor.

Receptor gets signal and shows that the light is reflected.

Thus, we landed on the moon.
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From:kinkyturtle
Date:January 7th, 2009 12:29 am (UTC)
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Yeah, I saw that! That was cool.
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