Data collected by NASA's Hubble Space Telescope over the past 20 years show Jupiter's Great Red Spot has been shrinking at an increasing rate to its current, and smallest, recorded size. The reduction is possibly due to the existence of eddies, that have been observed feeding into the planet-sized storm.
The Great Red Spot is, in essence, a vast, turbulent storm of astonishing size and ferocity. The storm system has persevered for roughly 300 years, so observations of its diminishing size have been met with great interest from the scientific community.
Since the early 1930s, astronomers have followed the apparent subsiding of Jupiter’s Great Red Spot. Data returned from Voyager 1 & 2 in 1979 estimated it to be roughly 14,500 miles (23,175 km) across. However subsequent readings have shown the massive anti-cyclonic storm receding, with today’s measurements from the Hubble Telescope estimating the Red Spot to be only 10,250 miles (16,496 km) across. That's a 29 percent decrease in the storm's length.
Astronomers have concluded that the storm is shrinking at an ever increasing rate, estimated at 580 miles (933 km) per year. Despite the fact that the spot has shrunk significantly whilst under observation, it is worth noting that the storm could still comfortably swallow the Earth with room to spare.
"In our new observations it is apparent very small eddies are feeding into the storm," states Amy Simon of NASA's Goddard Space Center, continuing, "We hypothesized these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot."
Looking to the future, the team of NASA scientists intend to further study the internal mechanics of the eddies in order to determine whether it is these atmospheric features that are expediting the shrinking of the Red Spot.
The storm will undoubtedly come under greater scrutiny in 2016, when NASA's Juno satellite will achieve polar orbit of the gas giant, heralding the start of its one year mission. The satellite's massive solar panels, necessary due to Juno's great distance from the Sun, will power a suite of equipment designed to probe within and through Jupiter's impressive atmospheric structure. The mission will hopefully return insightful information as to the composition of the Gas Giant, and of course, its trademark Great Red Spot.