Within the main asteroid belt, which lies between Mars and Jupiter, are two of the oldest and most massive surviving residents, Ceres and Vesta. The formation of Jupiter interrupted their growths, and during the past 4.5 billion years, they have taken opposite evolutionary paths. Vesta is a rocky asteroid whose face basaltic lava flows and impacts have changed. Ceres, on the other hand, remains basically in its icy primordial state, although cratered.
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