Venus is the closest planet to Earth and the brightest object in the night sky, with the exception of the moon, and has been referred to as both the Morning and Evening Star due to its luminosity. Venus is most striking for its thick atmosphere which covers the entire planet and obscures the view of the surface from space and Earth. The hidden surface of the planet was the subject of much curiosity and speculation before the myths were dispelled by probes and exploratory spacecraft. Science fiction writers in particular pondered what what be on the surface of Venus, speculating about possible life on the surface.

However, numerous probes sent to the planet would remove any lingering doubt over the possibility of life on Venus. The surface temperature averages at around 460 degrees C with the atmospheric pressure 92 times that of Earth's, the same as that found 1km under the oceans. The extremely high temperature is caused by a runaway greenhouse effect. Venus' atmosphere is predominantly composed of carbon dioxide with clouds of sulphur dioxide. Heat from the Sun becomes trapped and the planet gets warmer and warmer, to the point it is at today.

At its closest Venus passes 41.8km away from Earth, takes 225 Earth days to orbit the Sun and 243 days to complete one rotation. Venus' orbit is the closest of any planet to being circular, with an eccentricity of less that 0.01. The extremely slow rotation of Venus makes it stand out from the other planets, taking much longer to complete. Venus also spins in the opposite direction to Earth. Venus has no moons.

Venus has been the subject of a lot of the initial ideas of colonisation by Man of the Solar System. The discovery of the conditions on the surface seemed to all but rule out any human settlement on the surface, the extreme temperature and pressure would make life impossible. There has been some talk, however, of possible colonisation of the Venus' atmosphere. 50km above the surface the conditions are much more favourable and Earth-like. Floating cities filled with human-breathable air would float in the dense atmosphere, at that height the atmospheric pressure is the same as that of Earth and temperatures range from 0-50 degrees. A different approach could be to artificially cool Venus using giant mirrors or manipulating dust clouds. In just a few decades the planet would cool significantly enough to give conditions similar to Earth on the surface.

Venus is an interesting planet given its similar properties to Earth. It is also a living example of what a runaway greenhouse effect can do to a planet. The excessive CO2 content in the atmosphere has massively heated the planet beyond what it would be otherwise, a stark reminder of what could eventually happen to Earth.