Tuesday, February 3, 2009

The Crown of Tethys


The crater (450 kilometers or 280 miles across) is a remarkably well-preserved example of an ancient multi-ringed impact basin: The outer ring is defined by steep, cliff-like walls that descend to generally broad internal terraces. The inner ring is formed by a prominent, crown-shaped, 140-kilometer (88-mile) diameter circular band of icy mountains. Multi-ring basins are seen on rocky bodies as well as icy ones.

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