Archive for January 27th, 2010

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The moon in 3D!

January 27, 2010

Last month I sent in my completed logbook for the AL Lunar Club to Steve Nathan, the coordinator for that club. We struck up a conversation and he shared the above image and some information about it (with permission to post):

The Moon image is attributed to L. M. Rutherford.  The images were take on Sept. 15 and Nov. 13, 1864.  His original negatives were copied by many (!) 3D stereo card publishers for decades…into the early 1900’s.  Other phases of the Moon were also shot in 3D, but all took advantage of the libration effect. Similar 3D images exist for the planets, sunspots, meteors, etc.; all with limited, to no 3D effect. However, somewhere around here I have Neil Armstrong’s famous lunar bootprint…in 3D! (FYI: much of the NASA lunar program photography was done in 3D).  Intriguing, eh?!

If you don’t have a stereo-viewer (I don’t), don’t click on the image (leave it at column width), hold your head back at least a foot and a half from the screen (farther is easier), cross your eyes until the moons double up and then merge the two in the middle to make one bright 3D moon between the two flat ones.

Earlier I had asked if two cameras had to be widely separated geographically to get the stereopair. For making stereopairs of Earthly objects, two photos must be taken with the camera in slightly different places to simulate the separation between our eyes. Since the moon is a quarter of a million miles away, it seemed logical that you’d need the cameras to be as far apart as possible. But as you can read above, the two shots were separated not in space but in time. Steve wrote:

Libration alone will do the trick, the object of interest (the Moon) presents two different views of itself to the observer; increasing the baseline/camera separation would be redundant.

Libration is the “wobbling” of the moon over time as seen from Earth, because of the complex geometry of the Earth/Moon/Sun system. Go here for a more complete explanation.

Pretty darned cool; there is absolutely no reason I couldn’t give this a whirl as soon as the clouds clear out. If I get anything, I’ll post it here. In the meantime, here’s another version of the stereopair that I cleaned up a bit in GIMP. I like the sepia-toned classic version as well; use whichever tickles your fancy.

Finally, many thanks to Steve for sharing the image and the information!