science · 06 March 2015 · 10 years ago
In 2015, the NASA spacecraft, Dawn,entered orbit around the dwarf planet, Ceres, at 7:39 EST. The 7½ year journey of 3,100 million miles (4,900 million km) was made with steady acceleration from ion propulsion. It became the first spacecraft to orbit a dwarf planet. On its way (2011-12), it had explored the giant asteroid Vesta. Dawn returned many images of both bodies, the two most massive (largest and third-largest in size) in the asteroid belt between Mars and Jupiter. Ceres, discovered by Giuseppe Piazzi on 1 Jan 1801, is spheroidal, ave. 590 mi (590 km) diameter. As Dawn neared Ceres, its cratered surface showed some unusual small bright spots (perhaps ice). Vesta is ave. 318 mi (530 km) diameter.
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