February 5, 2009

Highway Interruptus

image by Jim Phillips

Linear rilles are flat-floored channels usually found paralleling edges of maria. The rilles form when the center of an impact basin and the maria within it subside, causing bending cracks along the edges. No basin is completely surrounded by these rilles - they all stop at some point. Jim's low Sun view of the Hypatia Rilles show that at least one linear rille previously extended further than it now does. The bottom, longer rille is Hypatia I and the shorter rille above it is Hypatia II (rilles are designated by Roman numbers). On most images II stops at the elongated crater that cuts it, but here you can see that it extended nearly to Moltke, the small bright crater at bottom center. It appears that the eastern end of II was covered by a later lava flow, but it can't be detected. Or perhaps, as the Clementine image suggests, the rille has been largely filled in by ray deposits (from Theophilus?).

Chuck Wood

Technical Details
Jan 31, 2009, 23:48-23:50 UT. TEC 200mm F/8 Flourite @ F/40.

Related Links
Rükl plate 35

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