A field of bright rays--created by ejecta from a crater--radiating to the north (top) from off camera (lower right) is seen in this view of Mercury taken September 21 by Mariner 10. Source of the rays is a large new crater to the south, near Mercury's South Pole. Mariner 10 was about 48,000 kilometers (30,000 miles) from Mercury when the picture (FDS 166749) was taken at 2:01 p.m. PDT, just three minutes after the spacecraft was closest to the planet. Largest crater in this picture is 100 kilometers (62 miles) in diameter.
The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.