image by Pete Lawrence, Selsey, England.
This wonderful image emphasizes the steep walls that surround the 207 km wide Humboldt crater. The walls look absolutely shear with no irregularities until the jumbled pile of slumped material is reached at their bottoms. The scarped rim is missing on the farside of the crater in the region behind the three craters on the floor of Humboldt and behind the nearby dark pyroclastic deposit. This area is not well imaged from space, but the poor Orbiter IV image shows that at least part of this missing zone occurs where Humboldt’s rim intersects a pre-existing crater. A more clear, non-overhead view, from Apollo 15 confirms that formation of Humboldt’s rim was severely modified by this pre-existing low spot. The very strong rim scarp occurs where Humboldt is nearly tangent to the older crater Barnard to the right. In this case, the adjacent crater seems to have been a buttress that supported a larger than normal scarp. Finally, the middle of the three craters on the farside of Humboldt’s floor is a famous concentric crater. Pete’s image is the only Earth-based view that I am aware of that hints at the existence of the inner donut.
Technical Details:
April 21, 2007, 19:35 UT. Celestron C-14 + Lumenera SKYnyx 2-0M + Astronomik red filter.
Related links:
Rükl plate 60
Pete’s spectacular web site
A new novel about the naturalist Humboldt and his compatriot Gauss.
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