The gas giant Jupiter's Great Red Spot may be about to lose its "greatness" as scientists at NASA have noticed that it has shrunk to its smallest size since it was first observed in the late 1800s, and they have yet to find out why.

The mammoth swirling storm used to be as immense as 25,500 miles across and three Earths could easily fit inside the Jovian tempest. When NASA's Voyager 1 and 2 flew by Jupiter in 1979, the storm drastically dropped in size to 14,500 miles across. Now, as seen through the cosmic eye of the Hubble Space Telescope, the Great Red Spot has reached it tiniest point, with a recorded 10,250 miles when measured on its longer axis.

Since the 1930s, astronomers have tracked its downsizing and surprisingly, they found out the phenomenon occurred more rapidly than what was usually observed. In 1995, when Hubble was newly launched into space, it took a picture of the Jupiter's Great Red Spot, which revealed it measured 13,020 miles across. Fourteen years later, when Hubble made adjustments with its optics, the storm further shriveled to 11,130 miles.

In 2012, the spot is estimated to have been shrinking by roughly 580 miles every year. From three Earths that the Great Red Spot could likely swallow, it may now only engulf one Earth-size planet. The once backyard treat to perennial onlookers may no more be a sight to behold especially now that its distinct oval shape has distorted into a circle.

"In our new observations it is apparent that very small eddies are feeding into the storm," said Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Maryland in a statement. "We hypothesized that these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot."

Could the Great Red Spot be demoted into a Red Dot? It's not yet that soon, said Xylar Asay-Davis of the University of California at Berkeley who, together with his team, conducted a past study about the storm.

"Velocity is a more robust measurement because the clouds associated with the Red Spot are also strongly influenced by numerous other phenomena in the surrounding atmosphere," he told, noting that changes in Jupiter's climate may have been causing the downsizing.

Simon added that they have yet to dig deeper into the motions of the small eddies and the dynamics of the Great Red Spot to find out how the shrinkage occurred.

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