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"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.
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
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.
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
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