Venus

Venus is the "sister planet" to the Earth. Our nearest neighbor in our Solar system, Venus has a similar size and density as Earth.

Venus is the third brightest object we observe in the sky after the Sun and the Moon.

Because it's orbit around the Sun is inside of ours, we see its position relative to the Sun change often. When we see Venus trailing the Sun, we call it the "evening star" and when Venus is ahead of the Sun it is the "morning star."

Since Venus' orbit is only 67 million miles from the Sun (compared with 93 million for Earth), she orbits the Sun in only 225 days and receives more intense radiation. Not surprisingly, the temperatures on Venus are much higher than those we see on Earth.

Venus rotates very slowly around its axis and makes a rotation in 243 Earth-days. The direction of rotation is in the opposite direction as Earth and is the only planet to rotate in the "retrograde" direction.

Venus' atmosphere which consists of carbon dioxide, sulphuric acid and other complex compounds, is very dense with pressures as much as 90 times that of Earth. These result in nearly perpetual clouds covering and hiding the surface from our view. It was not until radar mapping missions were sent to Venus that we were able to understand the surface topology.

The surface has plains, mountains, valleys and canyons. Impact craters are also found, but in numbers that suggest that the surface is much younger that that of Mecury or the Moon.

There have been many missions to Venus by the US and the Soviet Union. The Soviet Union's Venera space probes were early missions. in 1966, Venera 2 was a fly-by mission and Venera 3 impacted Venus. Venera 4 dropped an probe into the Venusian atmosphere and Venera 7 was a lander mission. in 1975, Venera 9 provided the first surface photographs and Venera 10 measured the atmospheric pressure and analyzed surface rock compositions.
Mariner 2 "fly-by" was NASA's first mission
In 1978, Pioneer 1 started radar mapping the surface, Pioneer Venus 2 entered the Venusian atmosphere and Venera 11 and 12 both made landing on the surface.
In the 1980s, Venera 13-16 added additional probes and radar mappings of Venus.
in 1990, Magellan made a detailed radar map of the surface