Illustration of clouds in the atmosphere of Venus. Clouds of sulphuric acid obscure the Sun and the rest of the sky. Venus has the hottest planetary surface in the solar system, with temperatures of nearly 500 degrees Celsius. This is due to its dense carbon dioxide atmosphere that traps the Sun's heat. Venus is 108 million kilometres from the Sun, around around two-thirds of the Earth-Sun distance, and is slightly smaller than Earth.