The oldest and largest storm in our solar system may be finally winding down.

New photographs from the Hubble Space Telescope suggest that the anticyclonic storm you my know as the Great Red Spot (GRS) is smaller than it has ever been. Researchers remain puzzled over what is causing the famously furious storm to calm down a bit.

“Recent Hubble Space Telescope observations confirm that the Great Red Spot (GRS) is now approximately 10,250 miles across, the smallest diameter we’ve ever measured,” said Amy Simon of NASA’s Goddard Space Flight Center in a press release.

The first confirmed viewings of the GRS date back to the 1800s. These early observations put the spot at roughly 25,500 miles across at its widest diameter. In 1979 when Voyager 1 and Voyager 2 flew by Jupiter, we were able to size the spot at 14,500 miles across. In 1995, Hubble measured the diameter as 13,020 miles across, and by 2009 it was at 11,130 miles. The storm is getting smaller but it is still huge. To give you a sense of how much bigger this storm is than Earth, our own diameter is a puny 7,917.6 miles.

By 2012, as more and more observational ability fell in the hands of amateur observers here on Earth, scientists became aware of an apparent increase in the spot’s actual rate of ‘shrinkage’ (Costanza, 1994). The reason behind the shrinkage, and why it’s happening faster and faster, remains a mystery to scientists.

One detail scientists have noticed are the small eddies that have appeared along the edges of the GRS. “In our new observations it is apparent that very small eddies are feeding into the storm,” said Simon. “We hypothesized that these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot.” Simon and her team plan to take a harder look at these eddies in the future to see if they are related to the spot’s changing size.

HT: HubbleSite

IMAGES: Jupiter by Cassini-Huygens by NASA/JPL/University of Arizona, Jupiter and the Great Red Spot by NASA, ESA, and A. Simon (Goddard Space Flight Center)

VIDEO: Space.com