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News Release Archive:

News Release 810 of 966

April 19, 1995 02:00 PM (EDT)

News Release Number: STScI-1995-21

Hubble Discovers New Dark Spot on Neptune

April 19, 1995: The distant, blue-green planet Neptune has again surprised astronomers with the emergence of a new great dark spot in the cloudy planet's Northern Hemisphere, discovered by the Hubble telescope.

Only last June, Hubble images revealed that a great dark spot in the Southern Hemisphere discovered by the Voyager 2 spacecraft during its 1989 flyby had mysteriously disappeared. The new dark spot is a near mirror image of the one found in the Southern Hemisphere. Bright, high-altitude clouds accompany the new northern dark spot. Atmospheric gases that flow up over the spot cool to form the methane-ice crystal clouds. The new spot might be a hole in Neptune's methane cloud tops, giving astronomers a peek at lower levels of the atmosphere.

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Credit: H. Hammel (Massachusetts Institute of Technology) and NASA