It is thought that Giovanni Cassini was the first person to observe the Great Red Spot.
The Great Red Spot on Jupiter has long been known, but scientists have just recently learned more about how and when formed. The huge storm that is responsible for the enormous swirl on the side of the largest planet in the solar system is believed to have been raging for more than 300 years and is larger than the entire Earth, as per a report in Newsweek.
Astronomers have modelled how the storm began and lasted for so long. They concluded that it may not be as old as previously believed, according to research published in the journal Geophysical Research Letters.
It was thought that Giovanni Cassini, who termed it the Permanent Spot, was the first person to observe the Great Red Spot, a gigantic storm situated in Jupiter's southern hemisphere. However, it wasn't until the 1830s that the red area was once more discovered and named the Great Red Spot (GRS). Some speculate that Cassini may have instead seen an earlier, larger storm on the planet's surface. To ascertain how the spot would have evolved and lasted for so long whether the Permanent Spot was an early form of the GRS researchers examined observations of the spot made over several centuries, starting in the 1600s.
Study co-author Agustin Sanchez-Lavega, professor at the University of the Basque Country, said in a statement, "From the measurements of sizes and movements we deduced that it is highly unlikely that the current GRS was the PS observed by G. D. Cassini. The PS probably disappeared sometime between the mid-18th and 19th centuries, in which case, we can say that the longevity of the Red Spot now exceeds 190 years at least."
The location was 24,233 miles across in 1879, and it has gradually reduced to 8,700 miles in diameter currently, gradually taking on a rounder shape rather than an oval one. "Various instruments on board the Juno mission in orbit around Jupiter have shown that the GRS is shallow and thin when compared to its horizontal dimension, as vertically it is about 500 km long," the author added.
After simulating the wind vortices sweeping across Jupiter's atmosphere, the researchers concluded that it was improbable that the GRS originated from the eruption of a massive superstorm, as is occasionally observed on Saturn. "We also think that if one of these unusual phenomena had occurred, it or its consequences in the atmosphere must have been observed and reported by the astronomers at the time," Mr Sanchez-Lavega continued.
The researchers discovered that in certain wind conditions, an extended storm cell may form, trapping the winds and producing a proto-GRS. This phenomenon, which has been detected at other Jupiter vortices in the past, would cause a shrinkage that is comparable to what we have been seeing from the GRS over time.