Eros
Eros is a large near-Earth asteroid, about 34 kilometres long, the first asteroid orbited and landed on by a spacecraft.
433 Eros was discovered in 1898, the first near-Earth asteroid found. It is shaped like a peanut or a stretched saddle, about 34 by 11 by 11 kilometres, and spins once every 5 hours and 16 minutes.
Eros was studied in detail by NASA's NEAR Shoemaker spacecraft, which orbited it from 2000 to 2001 and then landed. The surface proved to be covered in loose rock and dust, with boulders scattered across it and flat ponds of fine material in the bottoms of some craters. A huge saddle-shaped depression, named Himeros, marks one side.
Eros is an S-type asteroid, a stony kind thought to be related to ordinary chondrites. In the early twentieth century, observations of Eros during close approaches were also used to measure the distance between Earth and the Sun more precisely. It cannot hit Earth in the foreseeable future, but it is a relatively large object among those that come close.
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Level: Explorer Ages 10 and up