|Eros. Image captured from orbit by
433 Eros was the first near-Earth asteroid to be found and is the second-largest one known. It was discovered in 1898
by the German astronomer Gustav Witt (1866-1946), director of the Urania
Observatory in Berlin, and independently on the same day by the French astronomer
Auguste Charlois (1864–1910) in Nice.
|Close-up by NEAR-Shoemaker
Eros is an S-type asteroid. As
a member of the Amor group, Eros moves
in an orbit that crosses the orbit of Mars but does not intersect that of Earth, so there is no danger of it colliding
with us. It came about as close as it ever gets on January 23, 1975, when its
distance was about 0.15 AU (22 million km).
A 90-kg person on Earth would weigh about 60 grams on Eros, and a rock thrown
from the surface at 10 m/s (about a quarter the speed of a top pitcher's
fast-ball) would escape into space. Although gravity on Eros is very weak
it is strong enough to hold a spacecraft in orbit, as demonstrated when NEAR-Shoemaker entered orbit in February 2000.
NEAR-Shoemaker spent a year circling around the asteroid, sending back 160,000
pictures, and spotting more than 100,000 craters, about a million house-sized
(or bigger) boulders, and a layer of debris resulting from a long history
of impacts. Finally, on February 12, 2001, the little probe – never designed
to land – descended to the surface, returning its last image from
a height of just 120 m, before touching down.
||35 × 13 × 13 km
ASTEROIDS, CENTAURS, AND KUIPER BELT OBJECTS