The mystery of Jupiter’s Great Red Spot revealed

Jupiter has long been known for its Great Red Spot – but only recently have scientists learned more about how and how long ago it formed.

The giant vortex on the side of the Solar System’s largest planet is a massive storm that has long been thought to have been blowing for perhaps more than 300 years and is larger than the entire Earth.

Now, according to new research in the journal Geophysical Research Letters, astronomers have modeled how the storm formed and persisted for so long and deduced that it may not be as old as previously thought.

The Great Red Spot is a massive storm located in Jupiter’s southern hemisphere and was originally thought to have been first observed in the 17th century – notably by Giovanni Cassini, who called it the Permanent Spot (PS). The red spot was not documented again until the 1830s, after which it was referred to as the Great Red Spot (GRS), with some suggesting that Cassini may have observed another earlier large storm on the planet’s surface instead.

The researchers analyzed observations of the site over several centuries, dating back to the 17th century, and used models to determine how it could have formed and persisted for so long, and whether the PS was indeed an early version of the GRS.

“From measurements of magnitudes and motions, we conclude that it is highly unlikely that the present GRS is the PS observed by GD Cassini. The PS probably disappeared sometime between the mid-18th and mid-19th centuries, in which case we can say that the Red Spot Lifetime now exceeds at least 190 years,” study co-author Agustín Sánchez-Lavega, professor of physics at the University of the Basque Country (UPV/EHU), said in a statement.

In 1879, the spot was 24,233 miles in diameter and was slowly shrinking to its current size of 8,700 miles in diameter, becoming more round than oval in shape.

“Various instruments aboard the Juno mission in orbit around Jupiter have shown that the GRS is shallow and thin compared to its horizontal dimension, as it is about 500 km long vertically,” Sánchez-Lavega said.

Above the GRS, winds are blowing to the west at about 112 mph, while below the storm they are blowing to the east at about 93 mph. This created a north-south shear that generated a giant storm vortex.

The researchers modeled wind vortices blowing through Jupiter’s atmosphere and found that the GRS was unlikely to have formed through the merging of multiple vortices or through the eruption of a huge superstorm, as is sometimes seen on Saturn, the second largest gas body in the Solar System. giant.

“We also believe that if any of these unusual phenomena occurred, it or its consequences in the atmosphere must have been observed and reported by astronomers at the time,” Sánchez-Lavega said.

They found that if the winds were unstable in a certain way, they could create an elongated storm cell that would trap them and create a proto-GRS. This process has previously been observed in other vortices on Jupiter and would result in shrinkage similar to what we have observed from the GRS over the years.

“In our simulations, the supercomputers allowed us to discover that the elongated cells are stable when they rotate around the GRS circumference at the speed of Jupiter’s winds, as would be expected when they form due to this instability,” co-author Enrique García-Melendo, a physics researcher at the Universitat Politècnica de Catalunya-BarcelonaTech (UPC), said in a statement.

However, this explanation would require the vortex to spin at a very specific speed, as it would break up if too slow, or not remain stable if too fast.

The researchers hope to further investigate the GRS’s longevity and predict whether it will break up anytime soon.

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