Lightning on Venus, illustration. In the 1970s, the Russian Venera 11 and 12 probes detected lightning. The European Space Agency's Venus Express, in 2006-7, recorded lightning in the high atmosphere of Venus. The lightning rate on Venus is about half that of Earth. This is the hottest planetary surface in the solar system, with temperatures of nearly 500 degrees Celsius (730 degrees Kelvin). This is due to its dense carbon dioxide atmosphere that traps the Sun's heat in a 'runaway greenhouse effect'. The surface atmospheric pressure is around 90 times that on Earth. Clouds of sulphuric acid obscure the Sun and the rest of the sky. Venus is the second planet from the Sun, next in from Earth and around two-thirds of the distance at about 108 million kilometres from the Sun. It is regarded as a 'sister planet' to Earth because of its similar size, gravity and mass.