radar astronomy

Radar astronomy is the use of radar to measure the topography, rotation rate, and distance of objects in the solar system, including the Moon, planets, and asteroids, and to detect meteors. Ground-based radar astronomy, with the exception of meteor work, demands the use of large radio telescopes. Some space probes, notably Magellan at Venus and Mars Express, have been equipped with radar to study the surface and subsurface of planets from orbit.