image by John Sussenbach, Netherlands

Rümker is a perennially weird formation. It is a large collection of overlapping low domes that is older than the surrounding lavas of Oceanus Procellarum and SInus Roris. John's new image nicely shows the two distinct parts of the landform. Most of it is higher, bumpier and older than the lower, smoother and younger eastern quarter. A Clementine image confirms these observations and illustrates that all of Rümker, including the low zone is a different coloration - and hence composition - than the adjacent mare. That is too bad because from a black and white image you could argue that the material covering the low area is the same as the mare, but that is not true. It does seem to be similar in morphology to mare lavas, but how would they get high enough to cover part of Rümker? It could be that the low zone is an area that has subsided, but that won't explain why it is older and bumpier, only why it is lower.

Chuck Wood

Technical Details
14 February 2009 04.00 UT. C11 f/20 with DMK21UA4 camera

Related Links
Rükl plate 8


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