Jupiter’s Little Red Spot has become as strong as its big brother. The highest wind speeds in the smaller, more recent storm have reached 640 kilometers per hour, the same as those of the planet’s long-observed Great Red Spot. Amy Simon-Miller of NASA’s Goddard Space Flight Center in Greenbelt, Md., and her colleagues base their assessment on measurements that they took last April with the Hubble Space Telescope (SN: 5/13/06, p. 293: Available to subscribers at Hubble eyes Jupiter’s second red spot). The researchers describe their findings in an upcoming Icarus.
The increased intensity of Red Jr. might have contributed to its color change, the team says. The storm was originally white but by early 2006 had taken on a ruddy hue. About the diameter of Earth, the Jovian hurricane arose 6 years ago from the successive mergers of three storms first spied in the 1930s. Observations of these storms by the Voyager 1 and 2 spacecraft in 1979, as well as the Galileo craft nearly 20 years later, revealed that the top wind speeds had held steady at about 460 km/hour.
Hubble is the only telescope sharp enough to measure wind speeds on Jupiter. However, astronomers won’t use the telescope to make new measurements until early next year, when the planet moves farther from the sun’s glare, Simon-Miller says.