05.21.08
Using data from NASA's New Horizons spacecraft and two telescopes at Earth, an international team of scientists has found that one of the Solar System's largest and newest storms - Jupiter's Little Red Spot - has some of the highest wind speeds ever detected on any planet.
The New Horizons researchers combined observations from their Pluto-bound spacecraft, which flew past Jupiter in February 2007 with data from the Hubble Space Telescope orbiting Earth, and the European Southern Observatory's Very Large Telescope, which is perched on an Atacama Desert mountain in Chile. This is the first time that high resolution, close-up imaging of the Little Red Spot has been combined with powerful Earth-orbital and ground-based imagery made at ultraviolet through mid-infrared wavelengths.
Jupiter's "LRS" is an anticyclone, a storm whose winds circulate counterclockwise, which is in the opposite direction of a cyclone. It is nearly the size of Earth and as red as the similar, but larger and more well known, Great Red Spot (or GRS). The dramatic evolution of the LRS began with the merger of three smaller white storms that had been observed since the 1930s. Two of these storms coalesced in 1998, and the combined pair merged with a third major Jovian storm in 2000. In late 2005 - for reasons still unknown - the combined storm turned red.
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In this quasi-true-color view of Jupiter's Little Red Spot, generated using a New Horizons-LORRI mosaic in the red and green channels and a Hubble Space Telescope 410 nm map in the blue channel, the Little Red Spot appears with distinctly redder color than the south tropical disturbance to the north or the small oval to the southeast.
(This image appears in the June 2008 issue of the Astronomical Journal.)
Photo Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/HST |
The new observations confirm that wind speeds in the LRS have increased substantially over the wind speeds in the precursor storms, which had been observed by NASA's Voyager and Galileo missions in past decades. Researchers measured the latest wind speeds and directions using two image mosaics from New Horizons' telescopic Long Range Reconnaissance Imager (LORRI), taken 30 minutes apart in order to track the motion of cloud features. New Horizons obtained the images from a distance of approximately 1.5 million miles from Jupiter at a resolution of 8.9 miles per pixel. The LRS' maximum winds speeds of about 384 miles per hour far exceed the 156 mile-per-hour threshold that would make it a Category 5 storm on Earth.
"This storm is still developing, and some of the changes remain mysterious," said Dr. Andrew Cheng of the Johns Hopkins University Applied Physics Laboratory (APL), Laurel, MD, who led the study team. "This unique set of observations is giving us hints about the storm's structure and makeup; from this, we expect to learn much more about how these large atmospheric disturbances form on worlds across the solar system."
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http://www.jhuapl.edu/newscenter/pressreleases/2008/080520.asp
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