- Naming systems in astronomy have come under pressure in recent decades because of the huge amount of detailed knowledge of the solar system produced by space probes. In theory, the objects of the solar system with a visible solid surface, like asteroids, satellites and the inner planets, could require millions of names for their hills, mountain ranges, craters, valleys and other features. The problem began in the 17th century with the Moon, where most features are named after scientists of the past. The space age has brought similar problems including Venus (whose surface is ‘visible’ in radar wavelengths), where features have been named mainly after prominent real and fictional women, Mercury, where artists and authors figure, Mars, where scientists and place names dominate, and the satellites of the outer solar system, where mythological characters associated with the satellite names are preferred. The process is in the hands of a committee of the International Astronomical Union.