Lunar South Pole. Topographical map showing the Moon's South Pole (centre, middle). Colours represent altitude, from purple (over 9,000 metres below surface level), through to blue (3,000 below), green (zero altitude), yellow (2,000 metres above surface level), orange (4,000 metres above) and red (8,200 metres above). The Moon has a massive impact crater (bottom, middle), known as the South Pole-Aitken basin. It is seen here as the purple and dark blue patch just below the south pole and is 2,500 kilometres in diameter. The impact occured early in the Moon's history and hit the surface at an acute angle leaving behind a crater up to 13 kilometres deep. Data taken from by the Clementine spacecraft.