|Images of Jupiter’s Great Red Spot taken by the Hubble Space Telescope over a span of 20 years. |
Image Credit: NASA/ESA
The Great Red Spot is an anti-cyclonic storm on Jupiter similar to giant hurricanes on Earth. Observations dating back to the late 1800s gauged the Great Red Spot to be as large as 25,500 miles on its long axis. NASA’s Voyager 1 and Voyager 2 spacecrafts measured it to be 14,500 miles across in1979. In 1995, NASA’s Hubble Space Telescope showed the long axis of the spot at an estimated 13,020 miles across. And in a 2009 photo, it was measured at 11,130 miles across. The latest Hubble images confirm that the Great Red Spot now is approximately 10,250 miles across.
Astronomers have followed this downsizing since the 1930s. In 2012, amateur observations revealed a noticeable increase in the rate at which the spot is shrinking — by 580 miles per year — changing its shape from an oval to a circle.