| Profile | Fact |
|---|---|
| Diameter | 12104 KM |
| Moons | None |
| Orbit Period | 225 Days |
| Surface Temerature | 462 degrees celcius |
| First Record | 17th Century BC |
| Recorded By | Babylonian astronomers |
Venus has been known since prehistoric times. It is the brightest object in the sky except for the Sun and the Moon. Like Mercury, it was popularly thought to be two separate bodies: Eosphorus as the morning star and Hesperus as the evening star, but the Greek astronomers knew better.
The first spacecraft to visit Venus was Mariner 2 in 1962. It was subsequently visited by many others (more than 20 in all so far), including Pioneer Venus and the Soviet Venera 7 the first spacecraft to land on another planet, and Venera 9 which returned the first photographs of the surface
The first orbiter, the US spacecraft Magellan produced detailed maps of Venus' surface using radar. ESA's Venus Express launched in November of 2005 and arrived at Venus in April 2006. The Venus Express is conducting atmospheric studies, mapping the Venusian surface temperatures and the plasma environment.
Venus' rotation is somewhat unusual in that it is both very slow (243 Earth days per Venus day, slightly longer than Venus' year) and retrograde. In addition, the periods of Venus' rotation and of its orbit are synchronized such that it always presents the same face toward Earth when the two planets are at their closest approach. Whether this is a resonance effect or merely a coincidence is not known.