In With a Bang, Out With Ammonia: Saturn's Strange, 100-Year Storms

New radio observations show that behind Saturn's beige veneer lies a storm system with its own powerful rhythms.

By Matt Hrodey
Aug 17, 2023 6:00 PM
Saturn storms
An image of a Saturn megastorm taken by the Cassini spacecraft in 2011. (Credit: NASA/JPL/Space Science Institute)

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Jupiter’s Great Red Spot is an anomaly with no known equal in our solar system. The powerful anticyclone churns beneath the planet’s equator, where it produces winds estimated at between 270 and 425 mph. While it has shrunk in recent decades (to just a bit wider than Earth), it’s probably not going anywhere soon.

The spot has marked Jupiter since at least 1831, when amateur astronomer Samuel Heinrich Schwabe first observed the storm.

Saturn, by contrast, is a bit dull in appearance and lacks in a persistent spot. But a recent study revealed new details about the atmosphere’s surprisingly varied inner life. Just like Jupiter, storms have left their mark on Saturn, altering chemical compositions for years afterward.

Saturnian Storms

While Saturn’s major storms are not as persistent as the Great Red Spot, they splash across the ringed planet in dramatic fashion. Every 20 to 30 years, they spin up like massive hurricanes and swirl their way around the planet, though no one knows for sure what causes them. The last such megastorm broke out in 2010 and persisted for more than six months, long enough for the Cassini probe to study it.

The next storm will hit in 10 to 20 years, scientists predict. In the meantime, astronomers from two institutions – the University of California, Berkeley and the University of Michigan – are studying the long-last effects of these powerful storms. Like the Great Red Spot, they make lasting changes to their world, though you need special equipment to detect them.

The new study relied on observations from the Karl G. Jansky Very Large Array radio telescope back in 2015, about four years after the megastorm. The results were revelatory and allowed the researchers to look deep into Saturn’s cloud layers, which appeared disturbed. The storm had caused ammonia vapor to precipitate down to lower levels, perhaps for hundreds of years to come.

The team also identified a number of smaller storms that have raged around Saturn’s equator for potentially hundreds of years.

Two Worlds

The astronomers say Saturn’s epic storms are unique in their own way, though they lack the Red Spot’s special rouge. The ringed planet’s storms are true storms, unlike Jupiter’s “tropospheric anomalies,” which manifest in dark- and light-colored atmospheric bands.

Scientists have yet to explain why disturbances on each gas giant play out so differently.

Future study may rely further on radio telescopes, which reveal variations in Saturn’s atmosphere not seen in visible light.

“Despite bland looking at the visible wavelengths, different latitudes on Saturn show dramatic contrast in the radio emission,” the new paper says.

Radio waves help to reveal “heat transport, cloud formation and convection in the atmospheres of giant planets on both global and local scales,” said Imke de Pater, a University of California at Berkeley professor of astronomy and earth and planetary sciences, in a statement.


Read More: Saturn's Rings Formed Long After the Planet


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