Neptune -- from Eric Weisstein's World of Astronomy

The planet having the second greatest average distance from the Sun. It was discovered by Adams

in 1846. It is bluish green and has an atmosphere of hydrogen and helium, an icy mantle, and a rocky core. Neptune emits more energy than it receives from the Sun. It was be visited by Voyager 2 in Aug. 1989, which discovered six new satellites and a set of ring arcs. Neptune is the windiest planet in the solar system, with wind speeds of 600 m s^-1 (

Mach 1 at 59 K). The rings of Neptune are designated 1989N3R, 1989N2R, 1989N4R, and 1989N1R.

Although the average orbital distance of Neptune is less than that of Pluto, during certain periods, it is actually farther from the Sun than Pluto.

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