Jupiter's Great Red Spot is shrinking, and now we might know why

A massive storm has been raging on Jupiter for at least 350 years, and appears as an enormous red oval that is visible even from Earth. This captivating meteorological feature, located in Jupiter’s southern hemisphere, is known as the Great Red Spot.

Spanning over 10,000 miles wide, the intense anticyclone blows at speeds exceeding 200 miles per hour in a counterclockwise direction – a windstorm that is undeniably the largest in our solar system. And what’s even more intriguing is that the Great Red Spot has been shrinking.

Astoundingly, while the storm’s latitudinal reach has remained rather consistent, it has dramatically contracted longitudinally.

Extending over 40 degrees in the late 19th century, the Great Red Spot had shrunk to a mere 14 degrees by 2016, when NASA’s Juno spacecraft landed for a series of orbits around the planet.

Allure of the Great Red Spot

“Many people have looked at the Great Red Spot over the last 200 years and were as fascinated by it as I am,” said Caleb Keaveney, a Ph.D. student at Yale Graduate School of Arts and Sciences and lead author of a recent study.

“A lot of those people were not professional astronomers – they were just passionate and curious. That, plus the curiosity I see in people when I talk about my work, makes me feel like part of something bigger than myself.”

Despite rigorous study, the Great Red Spot continues to be a source of intrigue, shrouded in mystery. Astronomers are unsure about when the spot formed, what led to its formation, or even why it bears a red color.

Impact of transient storms

Keaveney conducted the research with Gary Lackmann of North Carolina State University and Timothy Dowling of the University of Louisville.

The team turned their focus towards evaluating the impact of smaller, transient storms on the Great Red Spot.

The researchers utilized an atmospheric model called the Explicit Planetary Isentropic-Coordinate (EPIC) model, which was developed for planetary applications in the 1990s by Dowling.

The team conducted a series of 3D simulations. Some of the simulations featured interactions between the Great Red Spot and smaller storms of varying frequency and intensity, while others did not include the smaller storms.

The analysis revealed that the presence of other storms actually strengthened the Great Red Spot, causing it to expand.

“We found through numerical simulations that by feeding the Great Red Spot a diet of smaller storms, as has been known to occur on Jupiter, we could modulate its size,” said Keaveney.

Relevance to Earth’s weather events

The researchers drew parallels between their models and long-lived high-pressure systems observed on Earth.

These intense systems – referred to as “heat domes” or “blocks” – occur routinely in the westerly jet streams that sweep across Earth’s mid-latitudes, playing a significant role in the occurrence of extreme weather phenomena like heat waves and droughts.

The systems interact with smaller, transient weather patterns, including high pressure eddies and anticyclones.

“Interactions with nearby weather systems have been shown to sustain and amplify heat domes, which motivated our hypothesis that similar interactions on Jupiter could sustain the Great Red Spot,” Keaveney emphasized.

“In validating that hypothesis, we provide additional support to this understanding of heat domes on Earth.”

According to Keaveney, more modeling work will not only refine these findings but also provide insight into the initial formation of the Great Red Spot.

Chemical enigma of Jupiter’s Great Red Spot

One of the enduring mysteries surrounding Jupiter’s Great Red Spot is its composition. Scientists have long speculated about the chemical makeup that gives the storm its distinctive hue.

Understanding the composition of the Great Red Spot not only helps in deciphering Jupiter’s atmosphere but also offers clues to atmospheric processes on other gas giants, both within our solar system and beyond.

As researchers continue to probe the depths of this colossal storm, they hope to unlock more secrets about its longevity, dynamics, and the unique conditions driving its persistence.

The study of the Great Red Spot on Jupiter is a testament to human curiosity and the drive to understand the unknown.

The study is published in the journal Icarus.

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