Storms Collide on Jupiter

NASA's Hubble Space Telescope has captured dramatic images of two swirling storms on Jupiter as they collided to form a truly titanic tempest.

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October 24, 2000 -- For the first time, scientists have been able to watch two of Jupiter's giant storms, each about half the size of Earth, colliding and merging to form an even bigger tempest. A similar merger centuries ago may have created Jupiter's famous Great Red Spot, a storm that is twice as wide as our planet and at least 300 years old.

"Usually when we've seen two of [the white ovals] approaching each other, they bounce back [apart]," said Glenn Orton, senior research scientist at NASA's Jet Propulsion Laboratory. But this time the storms came together in a complicated dance that scientists recorded using the Hubble Space Telescope and ground-based observatories.

Above: For sixty long years Jupiter's striking white ovals, pictured here in an image from NASA's Galileo spacecraft, existed as distinct storms. Since 1998 they've merged to form a titanic tempest second in size only to the Great Red Spot itself. Recent observations from the Hubble Space telescope captured for the first time two of the ovals in the act of coalescing.

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Seeing the collision of two such storms will help scientists understand more about the dynamics of Jupiter's atmosphere, says Agustin Sanchez-Lavega, an astronomer at Universidad del Pais Vasco, who reported the team's observations yesterday at a meeting of the American Astronomical Society in Pasadena. One question has been how deeply the roots of a storm at Jupiter's cloud tops extend into lower layers. In this year's merger, the upper layer seemed to move differently than underlying clouds.

Three white oval storms, in a band of Jupiter's atmosphere farther south than the Great Red Spot, became active about 60 years ago. In the following decades until 1998, they sometimes approached each other but never collided. In early 1998, two of the ovals were approaching each other as Jupiter went out of sight from Earth, behind the Sun. When the planet came back into view, the two had become one.

"We weren't able to see how they came together that time," Orton said.

Last year, the oval resulting from the 1998 combination approached the remaining one of the original three ovals. Each was a swirling high-pressure vortex, upwelling at the center and spinning winds counterclockwise to about 470 kilometers per hour. One was about 9,000 kilometers across, the other slightly smaller.

Above: These four Hubble Space Telescope images show steps in the consolidation of three "white oval" storms into one over a three-year span of time. [more information]

A third, darker oval, swirling clockwise instead of counterclockwise, formed temporarily between the two white ovals. That type of interceding system may be what usually keeps white ovals from colliding, the team proposed. But in this case, the middle storm appears to have been pushed even farther south and torn apart as all three passed near the Great Red Spot last December.

The disappearance of the opposite-swirling storm cleared the way for the two white ovals to meet.

Their collision dance began in March and lasted about three weeks. At the cloud tops, the storms circled around each other counterclockwise, then consolidated into a single oval about one-third wider than either had been beforehand. The ovals' approach and merger was viewed in various wavelengths, showing events at different depths, with a planetary telescope at Pic-du-Midi in France, NASA's Infrared Telescope Facility in Hawaii, and the orbiting Hubble Space Telescope, a facility of NASA and the European Space Agency.

JPL is managed for NASA by the California Institute of Technology, Pasadena. The Hubble Space Telescope is a facility of NASA and the European Space Agency. It is operated by the Space Telescope Science Institute, Baltimore, Md., which is managed for NASA by the Association of Universities for Research in Astronomy in Honolulu, Hawaii.

When Storm Collide -- NASA/GSFC Astronomy Picture of the Day

White Oval Clouds on Jupiter -- NASA/GSFC Astronomy Picture of the Day