Illustration showing Mercury's orbit of the Sun in relation to Earth's orbit. Mercury's orbit is inclined about 7 degrees to that of Earth's, which is known as the ecliptic. Mercury is the closest planet to the Sun, with an average distance from it of 57.91 million kilometres. It takes nearly 88 days to orbit the Sun. Mercury takes just under 59 days to rotate around its own axis. Its axis of rotation is almost vertical to the plane of its orbit and so neither hemisphere is ever tilted towards the Sun, meaning that it does not experience seasons. The alignment of planets and the Sun is known as a conjunction. When the planets are on opposite sides of the Sun it is known as a superior conjunction and when both are on the same side, an inferior conjunction. For an unlabelled version of this image see C058/0996.