Figure 183

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The very old crater Hipparchus has been nearly obliterated during eons of lunar change. Except for the circular pattern of subdued mountains (dashed line) that surround most of it, Hipparchus would not be recognizable. It is about 150 km wide. Beyond it near the horizon at the left is Sinus Medii (33, 44), the smooth dark- surfaced area that lies at the center of the Moon when seen from Earth. Part of the rim of Hipparchus is modified by "Imbrium sculpture," the pattern of ridges and grooves radial to Mare Imbrium, which affects the lunar surface for more than 1000 km from Imbrium. The four arrows show how the pattern radiates outward across this part of the Moon. (The Imbrium basin lies beyond the left horizon.) Craters and hills have been formed in the floor of Hipparchus and subsequently have been partially inundated by marelike plains deposits. The ejecta blanket of the much younger crater Horrocks (identified by H) is, in turn, spread over the marelike filling.   -M.C.M.

Report Source: NASA SP-362, Page 177, Figure 183

This web page was created by Francis Ridge for The Lunascan Project
Section Directories  33, 44, & 45
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