Venus is the second planet from the Sun and is similar in size, mass, and composition to Earth. However, Venus has an extremely hot atmosphere composed primarily of greenhouse gases like carbon dioxide that traps heat from the Sun, causing surface temperatures over 400 degrees Celsius. Venus lacks water on its surface due to the water having been broken down by sunlight and the hydrogen swept away by solar winds. The surface is a dry, desert-like landscape that is periodically renewed by volcanic activity.