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Jupiter’s iconic Great Red Spot is a massive storm that has been swirling for years in the atmosphere of the solar system’s largest planet.
But astronomers debate how old the whirlpool actually is, and when and how it formed. Some experts believe the whirlpool has been around for centuries, first spotted by Italian astronomer Giovanni Domenico Cassini in the 17th century, while others believe the storm is much more recent.
Now, new research suggests that the Great Red Spot formed about 190 years ago, meaning Cassini observed something else on Jupiter in 1665. Despite being newer than previously thought, the storm remains the largest and longest known whirlpool in the entire solar system, according to the researchers.
A study detailing the findings was published in the journal Neurology on June 16. Geophysical Research Letters.
Jupiter’s striking appearance is characterized by the stripes and patches of cloud bands and cyclonic storms that surround the planet. Its colors come from the composition of its various atmospheric layers, which are made up of ammonia, water ice, sulfur, and phosphorus gases, respectively. National Aeronautics and Space Administration (NASA)Fast jet streams shape clouds and stretch them into long ribbons.
Cyclonic storms on Jupiter can last for years because the gas giant has no solid surface to slow down the storms.
The Great Red Spot is a giant vortex in Jupiter’s atmosphere that is about 10,159 miles (16,350 km) wide, roughly the diameter of Earth. According to NASA:The storm towers more than 200 miles (322 kilometers) high.
Fierce winds slam along the storm’s boundaries at up to 280 miles per hour (450 kilometers per hour), and its distinctive red color is the result of chemical reactions in the atmosphere.
This iconic feature can even be seen with a small telescope.
It resembled a dark oval at the same latitude that Cassini first spotted through his telescope in the mid-1600s. He called the feature he spotted a “perpetual spot,” and Cassini and other astronomers observed it until they lost sight of the storm in 1713.
Then, in 1831, astronomers discovered a large elliptical storm at the same latitude on Jupiter, which continues to exist today and can still be observed today. But astronomers have long wondered whether the storms could be the same phenomenon, or whether they could be two different vortexes that appeared in the same place more than a century apart.
To solve this mystery, the team collected a huge amount of data by analysing historical drawings and images depicting the structure, location and size of the spots over time, which they used to create a numerical model to recreate the storm’s potential duration.
Ann Ronan Pictures/Print Collector/Getty Images
Astronomer Giovanni Domenico Cassini first observed what he called “permanent sunspots” on Jupiter in 1665. New research suggests that the Great Red Spot formed about 190 years ago, meaning Cassini observed something else on Jupiter in the 17th century.
“From our measurements of its size and motion, we infer that it is highly unlikely that the current Great Red Spot is the ‘permanent spot’ observed by Cassini,” lead study author Agustín Sánchez Lavega, professor of applied physics at the University of the Basque Country in Bilbao, Spain, said in a statement. “The ‘permanent spot’ probably disappeared between the mid-18th and 19th centuries, which would put the lifespan of the red spot at more than 190 years.”
The study authors said the permanent sunspot lasted for about 81 years, and none of the drawings the team analyzed mentioned the storm’s specific color.
“It was incredibly inspiring and exciting to read the notes and drawings that the great astronomer (Cassini) made about Jupiter and its stars, as well as his late 17th century papers describing this phenomenon,” Sanchez-Lavega said. “Others had investigated these observations before us, and we have now quantified the results.”
As well as examining historical data, the researchers also ran supercomputer simulations using a model of the behaviour of vortices in Jupiter’s atmosphere to investigate how the storm may have developed.
The team ran simulations to see whether the Great Red Spot formed from a giant superstorm — a merging of smaller vortices generated by Jupiter’s intense, alternating winds — or from wind instabilities that could give rise to atmospheric storm clusters — masses of air sprung up and down by winds that move as a single entity.
Vincenzo Pinto/AFP/Getty Images
In 2010, visitors to the Vatican Museums were able to view a series of paintings by Donato Creti from 1711. The third painting from the right depicts Jupiter in the night sky.
The first two scenarios produced cyclones, but the shapes and other features observed in the Great Red Spot were different.
“We believe that if one of these anomalies had occurred, it, or its effects in the atmosphere, would have been observed and reported by astronomers at the time,” Sanchez Lavega said.
But researchers believe that persistent atmospheric storms resulting from extreme wind instability created the Great Red Spot.
According to data from 1879, the storm was approximately 24,200 miles (39,000 km) long at its longest, but has become smaller and more rounded over time, and is currently approximately 8,700 miles (14,000 km) long.
A previous study published in March 2018 found that the Great Red Spot As the overall size decreases, the height increases.. 2018 Survey They also used archival data to study how the storm changed over time.
Data from modern space missions, such as NASA’s Juno spacecraft, have given astronomers unprecedented insight into the shape of storms.
“The various instruments on the Juno spacecraft in orbit around Jupiter show that it is shallow and thin compared to its horizontal length, and its vertical length is about 500 kilometers (310.7 miles),” Sanchez Lavega said.
Next, researchers will try to reconstruct the storm’s shrinkage rate over time to understand the processes that stabilize it and determine whether it will continue for many more years to come or disappear once it reaches a certain size (which may have been the fate of Cassini’s permanent spots).
“I love articles like this that delve into pre-photographic observations,” said Michael Wong, a research scientist at the University of California, Berkeley. As a co-author on the 2018 paper, I said after reading Sánchez-Lavega’s work, “While[our]paper used trace data going back to 1880, the new Sánchez-Lavega paper uses hand-drawn data going back even further. The supplementary material to this paper is also excellent.”
Wong was not involved in the new study.
“By continuously observing the weather and climate of these planets over long periods of time, we can learn a lot about these planets.”