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Apollo Discussions => The Reality of Apollo => Topic started by: bknight on December 12, 2015, 03:32:58 PM

Title: Determining distances on the moon
Post by: bknight on December 12, 2015, 03:32:58 PM
Here is an image From Apollo 15.
http://www.hq.nasa.gov/alsj/a15/AS15-84-11238HR.jpg
I have always read that distances were difficult to judge both on the moon and from the images.
So I'm attaching a poll for anyone to guess the distance to the mountain--
One rule: guess before you check it out.

Edit Second rule--don't post the correct answer, your guess is OK. :)
Title: Re: Determining distances on the moon
Post by: Ranb on December 12, 2015, 06:47:18 PM
Well, you said mountain and not hill.  While not appearing to be out of focus, the features on the mountain are not distinct.  I'm going with >45km.

Ranb
Title: Re: Determining distances on the moon
Post by: bknight on December 12, 2015, 06:53:42 PM
Well, you said mountain and not hill.  While not appearing to be out of focus, the features on the mountain are not distinct.  I'm going with >45km.

Ranb
I did say mountain, and I was dead wrong it is a HILL!(NASA's description)
EDIT:
I live on the coast and anything that has over 2700' from ground level is a mountain
Title: Re: Determining distances on the moon
Post by: Ishkabibble on December 13, 2015, 06:41:29 PM
Just a quick guess, I'd say about 23-24 Km away.

Not that I'm an expert on judging lunar distances.

I seem to remember how dumbfounded I was to see video from A17 where it looked like Schmitt was walking up to this little bitty rock, and by the time he got next to it, the thing was as big as a house and he could stand under part of it. 
Title: Re: Determining distances on the moon
Post by: raven on December 13, 2015, 08:37:24 PM
It doesn't help that this is a 2D picture, while the astronauts would have had some idea of depth thanks to stereoscopic vision. If you get a chance, look up some of the anaglyphs.  The moon looks very different with some depth to it.
 Still, yes, very difficult as a rule. No atmospheric haze, no scale sensitive objects, like trees or buildings, that help give a sense of scale.
Title: Re: Determining distances on the moon
Post by: bknight on December 13, 2015, 08:49:36 PM
It doesn't help that this is a 2D picture, while the astronauts would have had some idea of depth thanks to stereoscopic vision. If you get a chance, look up some of the anaglyphs.  The moon looks very different with some depth to it.
 Still, yes, very difficult as a rule. No atmospheric haze, no scale sensitive objects, like trees or buildings, that help give a sense of scale.
That would have been slightly better, but the image didn't have one of the stereo pairs, here is Mt Hadley, slightly closer http://www.hq.nasa.gov/alsj/a15/AS15-84-11247HR.jpg  but it looks further to me when compared.
Both were taken during the SEVA and probably did not have sufficient time for stereo pairs.
Title: Re: Determining distances on the moon
Post by: smartcooky on December 13, 2015, 11:54:41 PM
Keep in mind that for a person of average height, the horizon on the moon is only abut 2.4 km away which means that for one astronaut, if his fellow astronaut is about 5km away, he would be completely over the horizon
Title: Re: Determining distances on the moon
Post by: bknight on December 14, 2015, 12:01:42 AM
Keep in mind that for a person of average height, the horizon on the moon is only abut 2.4 km away which means that for one astronaut, if his fellow astronaut is about 5km away, he would be completely over the horizon
I think you mean below the horizon, but I get the idea.
Title: Re: Determining distances on the moon
Post by: BazBear on December 14, 2015, 11:09:35 AM
Keep in mind that for a person of average height, the horizon on the moon is only abut 2.4 km away which means that for one astronaut, if his fellow astronaut is about 5km away, he would be completely over the horizon
I think you mean below the horizon, but I get the idea.
Over the horizon = below the horizon. https://en.wikipedia.org/wiki/Over-the-horizon_radar
Title: Re: Determining distances on the moon
Post by: Zakalwe on December 14, 2015, 11:26:23 AM
It's a bit of a strange question, IMHO. Judging distance, from a single image, when the very basics aren't known is difficult if not impossible. No steroscopic view, no information on the focal length of the lens and so on.

It'd be just as difficult to judge the distance to this dune:

(https://upload.wikimedia.org/wikipedia/commons/3/36/Singing_Sand_Dunes.JPG)
Title: Re: Determining distances on the moon
Post by: bknight on December 14, 2015, 12:10:26 PM
It's a bit of a strange question, IMHO. Judging distance, from a single image, when the very basics aren't known is difficult if not impossible. No steroscopic view, no information on the focal length of the lens and so on.

It'd be just as difficult to judge the distance to this dune:

(https://upload.wikimedia.org/wikipedia/commons/3/36/Singing_Sand_Dunes.JPG)
Yes and no from me, do you remember the video of A16 where John and Charlie leave the LRV towards the "House rock".  Looked fairly close and smaller then when they got close to it.