for National Geographic News
A quick flyby of Jupiter by NASA's New Horizons probe has yielded the most detailed glimpse yet of the weather on the gas giant.
Images sent back from New Horizons earlier this year show stormy features similar to Earth's, including lightning on both of Jupiter's poles.
The images suggest the storms are caused by the heat from the planet itself, rather than the sun, and are maintained by circulation patterns that could be global in scale.
Perhaps even more important, Jupiter's weather appears to be different than it was when NASA probes last visited the gas giant, experts say.
"Jupiter has changed," said Dennis Reuter of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
"There's been a whole environmental change on this massive planet since Voyager and Galileo were there [in 1979 and 2003, respectively]."
Reuter is the lead author of one of several studies on Jupiter that appear in this week's issue of the journal Science.
Astronomers have observed lightning on other planets before, but until now polar lightning was only known to happen on Earth.
In a few brief exposures taken by New Horizons' cameras, lightning was shown to strike about every other second at Jupiter's poles.
(See related photo: "Jupiter Auroras 'Northern Lights on Steroids'" [March 30, 2007].)
A study of the images led by Kevin Baines at Caltech's Jet Propulsion Laboratory (JPL) showed roughly equal amounts of lightning in the planet's northern and southern hemispheres.
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