Jupiter’s Great Red Spot Revealed by Supercomputer Simulations; Giant Storm May Not Be Quite as Old as First Thought

Jupiter's Great Red Spot (GRS) is considered the largest and longest-loved vortex of all planets in the Solar System, yet its lifetime is debated, and the secret of its formation remains hidden.

Features of the Great Red Spot

The Great Red Spot is a persistent high-pressure region in Jupiter's atmosphere that produced an anticyclonic storm. This spot is a huge swirl that is long thought to have been blowing for more than 300 years.

The massive vortex is located in Jupiter's southern hemisphere, about 22 degrees south of the equator. It is believed to be first observed in the 17th century by Italian astronomer Giovanni Domenico Cassini who named it the Permanent Spot.

The giant swirl was not documented again until the 1830s, after which it was dubbed the Great Red Spot. This led other scientists to think that G. D. Cassini may have observed a different earlier huge storm on the surface of Jupiter.

New Insights About the Massive Vortex

In a new study, a team of researchers have modeled how the Great Red Spot formed and has persisted for so long. The details of their investigation were discussed in the paper "The Origin of Jupiter's Great Red Spot."

Led by physics professor Agustín Sánchez-Lavega from the University of the Basque Country, the researchers analyzed observations of the Great Red Spot made across several centuries, including those that date back to the 1600s. They also used models to find out if it was formed and stuck around for so long, and if the Permanent Spot was indeed an early version of the Great Red Spot.

Based on the measurements of sizes and movements, Lavega and colleagues concluded that it is highly unlikely that the current Great Red Spot was the Permanent Spot observed by G. D. Cassini. The Permanent Spot likely disappeared sometime between the mid-18th and 19th centuries. In this case, the longevity of the Great Red Spot currently exceeds 190 years at least.

In 1879, the spot was measured to be 24,233 miles across (38,999 kilometers). It has gradually shrunk to its current size of 8,700 miles (14,001 kilometers) in diameter and has steadily become more round than oval in shape.

The research team also modeled the vortices of wind that blow across the Jovian atmosphere. They found that it was unlikely that the Great Red Spot was created by the merging of several vortices or through the eruption of a massive superstorm as is often seen on Saturn.

The astronomers also discovered that if the winds were unstable in a certain way, it could produce an elongated storm cell that generates a proto-Great Red Spot. Such a mechanism has been observed before at other Jovian vortices and would result in a storm system similar to what has been observed from the Great Red Spot over the years.

In their supercomputer simulations, the models enabled the scientists to discover that the elongated cells are stable when they rotate around the periphery of the Great Red Spot at the speed of Jovian winds. This is expected during their formation because of this instability.