The Hubble Space Telescope reveals that wind speed on the fringes of the raging storm has increased by about 8 percent between 2009 and 2020.

It is perhaps the most famous storm in our solar system: the Great Red Spot on Jupiter. The storm is bigger than the earth and has been raging for centuries. And although astronomers have been observing it for a long time, they still don’t quite understand what drives the storm and how it has been able to hold out for so long. However, new insights – based on data from the Hubble Space Telescope – may help answer these outstanding questions.

8 percent

Based on observations from Hubble, researchers conclude that the speed of the winds on the outer edge of the Great Red Spot increased by about 8 percent between 2009 and 2020. Scientists are not yet able to properly explain the higher speed. “That’s tricky because Hubble can’t see the storm’s underside very well,” said study researcher Michael Wong. “Everything below the cloud cover is not visible in the Hubble data. But this (the discovery that the outer winds have started to blow faster, ed.) is an interesting piece of the puzzle that can help us understand what drives the Great Red Spot and how it conserves its energy.”

Thanks to Hubble

As mentioned, the new insights are due to Hubble, who has regularly observed the Great Red Spot for years. “This is something only Hubble can do,” Wong said. “Hubble’s longevity and ongoing observations make this disclosure possible.”

The rotational speed of the winds on the periphery of the Great Red Spot is much higher than that of winds on the inside. Image: NASA, ESA, Michael H. Wong (UC Berkeley).

Small change

But even with Hubble’s record, it’s a miracle that we now know that the speed of the winds on the edge of the Great Red Spot has increased. Because an 8 percent increase in 11 years may seem significant, but it means that the winds have started blowing less than 2.5 kilometers per hour per Earth year. “We’re talking about such a small change that we wouldn’t even have noticed it if we hadn’t had 11 years of Hubble data,” said study researcher Amy Simon.

The Great Red Spot in close-up. This image was taken by spacecraft Juno, which is currently orbiting Jupiter and should provide more insight into what goes on under the cloud cover. Image: NASA/JPL-Caltech/SwRI/MSSSImage processing by Kevin M. Gill, © CC BY.

Despite the new insights, the Great Red Spot remains a rather mysterious phenomenon. Moreover, the higher wind speed at the storm’s edge isn’t the only change the storm is experiencing; Previously, researchers have already shown that the storm has also become smaller and more circular rather than oval in the past century. While it has led some to believe that the Great Red Spot is past its prime, researchers are confident it will be around for a while.