June 2, 2016

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Hip, Hip, Hooray for Hippalus

Originally published April 21, 2006

Hippalus rille-wesImage by Wes Higgins

The standard of excellence for the Hippalus Rilles east of Mare Humorum is the now classic Stephen Keene image showing the area under grazing illumination. That is still the benchmark for low Sun imaging, but Wes’ recent view of the rilles achieves a new standard for higher angles of illumination. There are many stories to decipher from this image. At top right are closely aligned secondary craters from Bullialdus (just out of the image). These are not long secondary crater chains as seen at images but rarely seen from Earth. These rilles are narrower and shallower than the Hippalus rilles and not obviously related to sagging of the Humorum basin. A thorough study of the tectonics of this area is needed!

Chuck Wood

Technical Details:
April 8, 2006. 18″ Reflector, FL=9000mm, Infinity 2-1 camera, MAP processing, stack of 500 frames.

Related Links:
Rükl plates 52 & 53
Wes’ website

Yesterday's LPOD: ISS Over the Moon

Tomorrow's LPOD: Crater Chains and Unknown Rille


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