July 14, 2014

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A Northerly View

image by Maurice Collins, New Zealand

What's unusual about this image? First, it is a visualization of the LRO altimetry rather than an image; and second, look at the direction of illumination - its from due north. Maurice constructed this image using Jim Mosher's invaluable LTVT software to see how visible the saucers on the floor of Ptolemaeus (#1) would be compared to normal lighting from the east or west. Danny Caes had asked that question about a previous LPOD, and the answer is, not really very different - still detectable with low angle illumination. The visualization also highlights rather well the crease-like rille (2) just north of the Ancient Thebit ghost crater. This delicate rille has been seen before, but this new view makes it look like the north-eastern side bends down more than the opposite does. Number 3 looks like a megadome, like the one near Gardner, but looking at an image shows that it is more of a kipuka - a piece of high standing older lava surrounded by younger material. Nearby (4) is a slightly elevated (~150 m) rise of dark, younger lava - I am surprised, for I thought it would be lower than the older lava. Many other roughly circular rises occur, but a linear also is hinted at with this northern lighting. Between the two 5's is a straight feature made up of mare ridge segments. Finally, as an unnumbered bonus, Maurice pointed out the apparent east to west arcuate fault crossing the southern floor of Alphonsus. The eastern side of this feature is seen to be a rille on LRO, but the fault nature was unknown to me until seeing this visualization. Has anyone else seen it before?

Chuck Wood

Related Links
21st Century Atlas chart 16.

Yesterday's LPOD: Really, It's a Moon Picture

Tomorrow's LPOD: Polar Panorama


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