These NASA Hubble Space Telescope views of the blue-green planet Neptune provide three snapshots of changing weather conditions. The images were taken in 1994 on October 10 (upper left), October 18 (upper right), and November 2 (lower center), when Neptune was 2.8 billion miles (4.5 billion kilometers) from Earth.Hubble is allowing astronomers to study Neptune's dynamic atmosphere with a level of detail not possible since the 1989 flyby of the Voyager 2 space probe. Building on Voyager's initial discoveries, Hubble is revealing that Neptune has a remarkably dynamic atmosphere that changes over just a few days.The temperature difference between Neptune's strong internal heat source and its frigid cloud tops (-260 degrees Fahrenheit) might trigger instabilities in the atmosphere that drive these large-scale weather changes. In addition to hydrogen and helium, the main constituents, Neptune's atmosphere is composed of methane and hydrocarbons, like ethane and acetylene.
Published: August 2, 1998