Fresh Rim of Slipher S
November 28, 2012
Distinctive asymmetrical ejecta surrounds a 140 meter (459 feet) diameter crater in the lunar highlands. The distinctive wave-like texture may look a little bit like a terrestrial beach, but it's actually impact ejecta on the rim of the crater Slipher S (26 km diameter), which is located on the lunar farside at the edge of the larger and older crater Slipher. Notice that there are only a few small craters dotting the surface, and so the rim is well preserved. To a lunar geologist, the lack of impact degradation on a surface like this one indicates a (relatively) young age, and in fact this crater is currently mapped as an Eratosthenian-aged crater. You are actually looking at some of the deepest materials excavated by this crater. When impact craters form, the rocks excavated from the deepest parts of the crater actually fall near the rim. In effect nature is providing a drill hole to the subsurface bringing deep rocks right to the surface.