Secrets of Jupiter’s Great Red Spot Revealed

Jupiter has long been famous for its Great Red Spot, but only recently did scientists learn more about how and how long ago it formed.

The enormous vortex on the side of the solar system’s largest planet is a massive storm, long thought to have raged for more than 300 years, and larger than the entire Earth.

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

The Great Red Spot is a massive storm in Jupiter’s southern hemisphere and was originally first observed in the 17th century, most notably by Giovanni Cassini, who named it the Permanent Spot (PS). However, the red spot was not documented again until the 1830s, after which it was referred to as the Great Red Spot (GRS), with some thinking that Cassini may have observed another previous 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 formed and survived for so long, and whether the PS was indeed an early version of the GRS.

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

In 1879 the site was 39,233 miles in diameter, and it has slowly shrunk to its present size of 8,700 miles in diameter, becoming more round than oval in shape.

“Several instruments on board the Juno mission orbiting Jupiter have shown that the GRS is shallow and thin compared to its horizontal size, as it is about 500 km vertically long,” Sánchez-Lavega said.

Over the GRS, the wind will blow to the west at a speed of about 180 km/h, while below the storm it will blow to the east at a speed of about 150 km/h. This created a north-south shear, creating the giant storm vortex.

The researchers modeled the wind vortices blowing through Jupiter’s atmosphere and found that it was unlikely that the GRS was formed by the merger of multiple vortices, or by the eruption of a massive superstorm, as sometimes seen on Saturn, putting it on a second largest gas in the solar system. huge.

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

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

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

However, this explanation would require the vortex to spin at a very specific speed, because it would fall apart if it were too slow, or wouldn’t remain stable if it were too fast.

The researchers hope to further investigate the lifespan of the GRS and predict whether it will disintegrate soon.

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