Neptune
This picture of Neptune was taken by Voyager 2 on August 20, 1989. One of the great cloud features, dubbed the Great Dark Spot by Voyager scientists, can be seen toward the center of the image. It is at a latitude of 22 degrees south and circuits Neptune every 18.3 hours. The bright clouds to the south and east of the Great Dark Spot constantly change their appearances in periods as short as four hours. (Copyright Calvin J. Hamilton)

The Interior of Neptune
Our knowledge of the internal structure of Neptune is inferred from the planet's radius, mass, period of rotation, the shape of its gravitational field and the behavior of hydrogen, helium, and water at high pressure. This cut-away view shows Neptune composed of an outer envelope of molecular hydrogen, helium and methane roughly the mass of one to two Earths. Below this region Neptune appears to be composed of a mantle rich in water, methane, ammonia, and other elements. These elements are under high temperatures and pressures deep within the planet. The mantle is equivalent to 10 to 15 earth masses. Neptune's core is composed of rock and ice, and is likely no more than one Earth mass. (Copyright Calvin J. Hamilton)

 HST Observes Triton and Neptune
This mosaic combines an almost true-color picture of Neptune taken by the Hubble Space Telescope's (HST) Wide Field Planetary Camera (WFPC), with a picture of Triton taken with the HST's Faint Object Camera. Although faint, the image of Triton vaguely shows a brighter equatorial region. The south pole is to the lower left.

The picture of Neptune shows a bright cloud feature at the south pole, near the bottom of the image. Bright cloud bands can be seen at 30S and 60S latitude. The northern hemisphere also includes a bright cloud band centered near 30° N latitude. (Courtesy of Ted Stryk)