December 31, 2012 in Science
“Jupiter, the most massive planet in our solar system — with dozens of moons and an enormous magnetic field — resembles a star in composition, but it did not grow big enough to ignite. The planet’s swirling cloud stripes are broken by storms, the most massive being the Great Red Spot”
“The spot, which is a cold region averaging about 110 Kelvin (minus 260 degrees Fahrenheit) is so wide about three Earths could fit inside its boundaries.
Jupiter’s atmosphere has a zig-zag pattern of twelve jet streams which make up its signature pastel-toned bands. Earth, by comparison, has only two jet streams. The Great Red Spot is sandwiched between two of these jets streams, forcing the winds that power those perimeter winds to deflect around the spot.
Spacecraft observations of the way bands of high winds scream past the Red Spot show how the spot — inaccurately described as a storm — is actually far calmer at its center than other parts of the Jovian atmosphere. The winds at the center are just 9 or 10 miles per hour, whereas around the perimeter they exceed 200 miles per hour.”
“One of the most intriguing findings shows the most intense orange-red central part of the spot is about 3 to 4 Kelvin (5 to 7 degrees Fahrenheit) warmer than the environment around it, said Leigh Fletcher, the lead author of the paper, who completed much of the research as a postdoctoral fellow at JPL and is currently a fellow at the University of Oxford in England. This temperature differential might not seem like a lot, but it is enough to allow the storm circulation, usually counter-clockwise, to shift to a weak clockwise circulation in the very middle of the storm.”
Embryonic Earth – Great Red Spot Dynamics
New thermal images from powerful ground-based telescopes show swirls of warmer air and cooler regions never seen before within Jupiter’s Great Red Spot.
“The observations reveal that the reddest color of the Great Red Spot corresponds to a warm core within the otherwise cold storm system, and images show dark lanes at the edge of the storm where gases are descending into the deeper regions of the planet.”
“This is our first detailed look inside the biggest storm of the solar system,” said Glenn Orton, a senior research scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who was one of the authors of the paper. “We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated.”
“These three natural-color Jupiter images were made from data acquired on May 15, June 28 and July 8, 2008, by JPL’s Wide Field Planetary Camera 2. Each one covers 58 degrees of Jovian “latitude” and 70 degrees of “longitude” (centered on 5 degrees South latitude and 110, 121 and 121 degrees West longitude, respectively). ”
The oval was white in November 2005, it slowly turned brown in December 2005, and then red (similar to the Great Red Spot) in February 2006.
“Curiously, no one knows precisely why the Great Red Spot itself is red. A favorite idea is that the storm dredges material from deep beneath Jupiter’s cloudtops and lifts it to high altitudes where solar ultraviolet radiation–via some unknown chemical reaction–produces the familiar brick color.
“The Great Red Spot is the most powerful storm on Jupiter, indeed, in the whole solar system,” says Orton. The top of the storm rises 8 km above surrounding clouds. “It takes a powerful storm to lift material so high.”
“These four images of clouds in a portion of Jupiter’s southern
hemisphere show steps in the consolidation of three “white oval”
storms into one over a three-year span of time. They were
obtained on four dates, from Sept. 18, 1997, to Sept. 2, 2000, by
NASA’s Hubble Space Telescope. The widths of the white ovals
range from about 8,000 kilometers to 12,000 kilometers (about
5,000 miles to 7,500 miles).”