Jupiter’s trademark Great Red Spot—a swirling storm feature larger than Earth—has shrunk to its smallest size ever measured, astronomers report.
The reasons for the shrinkage is unknown, but it’s accelerating, astronomers said. If it continues at recently measured rates, the famous blotch will be gone by about 2030.
If Earth’s surface were spread out like an orange peel, about one and a half of those would fit within the Red Spot today. But in 1979, that number was over three—and back in Victorian days, it was estimated around 10.
Recent NASA Hubble Space Telescope observations show the planetary pimple is about 10,250 miles (16,500 km) wide, said Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Md.
Observations as far back as the late 1800s gauged the Red Spot to be as big as 25,500 miles (41,000 km) on its long end. And NASA’s Voyager 1 and Voyager 2 flybys of Jupiter in 1979 measured the storm as 14,500 miles (23,300 km) across.
Beginning in 2012, amateur observations revealed a noticeable acceleration in the shrinkage—to 580 miles (930 km) per year—changing its shape from an oval to a circle, astronomers said.
“It is apparent that very small eddies are feeding into the storm” on the gas-giant planet, said Simon. “These may be responsible for the accelerated change” by altering the storm’s internal dynamics and energy. Her team plans to study the eddies’ motions and the internal storm dynamics to determine whether the eddies can feed or sap momentum entering the upwelling vortex, causing the shrinkage.
Source : http://www.world-science.net/