Eros

Asteroid 433, size 7 × 16 × 35 km, discovered in 1898 by G. Witt. It was the first asteroid to be discovered with an orbit that brings it within the orbit of Mars. In 1931, when it came within 23 million kilometres of the Earth, measurements of its position were used in an attempt to determine the scale of the solar system more accurately than had been possible previously.