image/gif It takes Neptune 164.8 Earth years to orbit the Sun. On 11 July 2011, Neptune completed its first full orbit since its discovery in 1846. This image of Neptune was taken by Voyager 2 less than five days before the probe's closest approach of the planet on Aug. 25, 1989.
In 1965, 4 years before the Moon landing, the Mariner 4 Mars flyby crushed fantasies but began Mars exploration. Many hoped for pictures of life on Mars. Mariner 4 revealed a desert covered with craters much like the Moon. The photos captured a curious world’s attention, and showed we are alone.caltech.edu