Lunar Features — Southeast Quadrant
Hipparchus is a very large walled plain 160 km (100 miles) wide, with somewhat irregular, highly-eroded borders that some observers say have a hexagonal shape. Hipparchus has been described as a miniature version of Mare Crisium. Because the mountains that ring this formation are not particularly high, Hipparchus’s outline is recognized only when near the Moon’s terminator, and is badly washed out by the Sun’s light at all other times. Although the bordering mountains may rise as much as 1200 m (4000 ft) above the crater’s floor, they are almost level with the ground that surrounds the exterior of the formation, so there is little contrast except under very low Sun angles. This is truly an ancient crater, left over from the Imbrium impact. Its southwest side is almost obliterated. Three distinct valleys break through the southeastern rim, further interrupting the outline of this crater. One of these valleys emanates from Hipparchus G, a fine bowl crater on the crest of the east wall.
KeywordsDepression Amid Hexagonal Trench Ghost
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