Picture this: a hurricane that’s been raging for longer than your country has existed. This Great Red Spot is still present in Jupiter’s atmosphere, more than 300 years later. While our most powerful storms on Earth barely last a few weeks, Jupiter’s Great Red Spot has been churning relentlessly, captivating astronomers and curious minds alike. Measuring 16,350 km (10,160 mi) in width as of 3 April 2017, the Great Red Spot is 1.3 times the diameter of Earth.
This isn’t just any weather system. We’re talking about a storm so massive that The Great Red Spot is ~3 times the size of Earth. Yet despite centuries of observation and cutting-edge space missions, this crimson giant continues to guard its secrets. What makes it tick, why does it persist when everything else fades away, and how does it compare to the weather we know on Earth?
A Storm Older Than Nations
You might think hurricanes are temporary visitors, but Jupiter’s Great Red Spot laughs at our earthbound storms. Continuous observations began in 1878, with earlier recorded sightings dating back centuries, when continuous observations began. A similar spot was observed from 1665 to 1713; if this is the same storm, it has existed for at least 360 years, but a study from 2024 suggests this is not the case. The earliest possible sightings go back even further, with some astronomers believing they spotted this massive vortex in the 1600s.
Recent research has thrown a curveball into this timeline, though. However, there is no evidence for the existence of a Great Red Spot between 1713 and 1831, although such legendary astronomers as Messier and Herschel were observing alongside countless contemporaries. Maybe the Spot isn’t as permanent as we’ve thought? Perhaps the Spot that Cassini and his contemporaries saw had vanished by 1713, and the one we know today formed more than 100 years later? This means the storm we see today might be “only” around two centuries old, which still makes it older than most countries on Earth.
Size That Defies Imagination
Trying to grasp the sheer scale of Jupiter’s Great Red Spot is like trying to imagine the size of the ocean while standing on a beach. The Great Red Spot is 10,159 miles (16,350 kilometers) wide, which is about 1.3 times the width of the Earth (7,918 miles or 12,740 km). Picture being able to drop our entire planet into this storm with room to spare on all sides.
The storm wasn’t always this “small,” though. When it was first observed in detail in the late 19th century it was estimated to have been about 30,000 miles (48,280 km) wide, over three times the width of Earth! Around the turn of the 19th century, the spot was around 48,000 km (30,000 miles) wide. At the time of Voyager 1’s visit in 1979, the spot had a length of around 23,000 km (14,300 miles). Even as it shrinks, this colossal storm remains one of the most impressive features in our solar system.
Winds That Would Shred Earthly Storms
You think Earth’s hurricanes are powerful? Jupiter’s Great Red Spot generates winds that would make our strongest storms look like gentle breezes. Located 22 degrees south of Jupiter’s equator, it produces wind-speeds up to 432 km/h (268 mph). The Great Red Spot produces winds up to 432 km/h (268 mph). This is much stronger than the strongest hurricanes that hit Earth, which have maximum speeds of around 281 km/h (175 mph).
These aren’t just numbers on a chart. Winds inside this Jovian storm reach speeds up to 268 mph. To put this in perspective, the most devastating hurricanes that hit Earth typically peak at around 185 mph. Jupiter’s storm maintains winds nearly twice that speed constantly, day after day, year after year. The storm rotates counterclockwise, completing one full rotation in roughly six Earth days, which seems almost leisurely given its massive size.
The Mystery of Its Crimson Color
One of the most captivating aspects of the Great Red Spot isn’t just its size or longevity, but its distinctive color that gives the storm its name. Despite its iconic color, researchers aren’t entirely sure what causes the spot to appear red. Some researchers think it could be due to chemicals like ammonia in the upper part of the storm. Scientists have proposed various theories, from sulfur compounds to complex organic molecules, but the exact cause remains elusive.
What makes this even more intriguing is that the color isn’t constant. Though it is called the Great Red Spot, this storm changes color. Aside from being red, it can be as dark as brick red and as light as pale salmon. There are times when it can also be white. Since 2014, it has been taking on a ruddy orange color that is slowly intensifying, according to NASA. The change could be due to changes in the storm’s chemical composition or the distribution of gasses within and above it. This color-changing ability adds another layer of mystery to an already fascinating phenomenon.
Why Earth’s Storms Die While Jupiter’s Endures
Here’s where Jupiter and Earth show their fundamental differences. On our planet, hurricanes need warm ocean water to survive, and they quickly weaken when they hit land or cooler waters. Unlike Jupiter, the Earth has land masses that cause major storms to lose energy due to friction with a solid surface. Without this feature, Jupiter’s storms are more long-lasting. Jupiter has a completely different setup that allows its storms to persist.
A significant factor in its longevity is the fact that Jupiter, as a gas planet, has no surface, and thus there is no friction to slow the storm, according to JStor Daily. The long lifetime of the Red Spot may be due to the fact that Jupiter is mainly a gaseous planet. It possibly has liquid layers, but lacks a solid surface, which would dissipate the storm’s energy, much as happens when a hurricane makes landfall on the Earth. Without landmasses to break up the flow, Jupiter’s storms can maintain their structure indefinitely.
Additionally, On the Earth, the energy to power our storm systems comes from sunlight. Jupiter is too far from the Sun and receives very little energy. The energy needed to power all the turbulence in Jupiter’s atmosphere comes from heat released from the planet’s core. This internal heat source provides a steady energy supply that doesn’t depend on external conditions.
The Juno Mission’s Groundbreaking Discoveries
For centuries, astronomers could only observe the Great Red Spot from the outside, but NASA’s Juno mission changed everything when it arrived at Jupiter in 2016. Data collected by NASA’s Juno spacecraft during its first pass over Jupiter’s Great Red Spot in July 2017 indicate that this iconic feature penetrates well below the clouds. Juno data indicate that the solar system’s most famous storm is almost one-and-a-half Earths wide, and has roots that penetrate at least 200 miles (300 kilometers) into the planet’s atmosphere.
The mission’s findings were truly remarkable. They discovered that the roots of the Great Red Spot extend to at least 240 kilometers below the cloud tops, as far as down the microwave radiometer could see. In a study published today in Science, Weizmann Institute of Science researchers and their collaborators on NASA’s Juno mission to Jupiter report that this spot – really a giant, persistent storm – extends to a depth of about 500 kilometers below the planet’s clouds. This depth is comparable to driving from New York to Nashville straight down through Jupiter’s atmosphere.
The authors determined that the spot reaches a maximum depth of about 300 miles (500 kilometers) below the cloud tops. As deep as this seems, the Great Red Spot is still much shallower than the enormous jets of wind that surround and power it, the researchers said; those bands of wind extend to depths of about 2,000 miles (3,200 km) below the cloud tops.
How Jupiter’s Atmosphere Differs from Earth’s
Understanding the Great Red Spot requires grasping how fundamentally different Jupiter’s atmosphere is from ours. Circulation in Jupiter’s atmosphere is markedly different from that in the atmosphere of Earth. The interior of Jupiter is fluid and lacks any solid surface. While Earth’s weather is driven by temperature differences between land and sea, Jupiter operates on entirely different principles.
The two main constituents of the Jovian atmosphere are molecular hydrogen (H2) and helium. It is mostly made of molecular hydrogen and helium in roughly solar proportions; other chemical compounds are present only in small amounts and include methane, ammonia, hydrogen sulfide, and water. This composition creates conditions unlike anything we experience on Earth, where the atmosphere thins out gradually without a solid surface to provide a boundary.
Jupiter’s distinctive banded appearance results from complex atmospheric dynamics. Thus, belts and zones are Jupiter’s equivalents of the familiar high- and low-pressure systems that cause our weather on Earth. However, a major difference between Jupiter and Earth is that Jupiter’s rapid rotation has caused these systems to wrap all the way around the planet, instead of forming localized circulating storms, as on our own world. Jupiter’s great size and fast rotation make the Coriolis effect very strong. Instead of being split into just three smaller cells encircling each hemisphere, as on Earth, Jupiter’s circulation cells split into many alternating bands of rising and falling air.
The Shrinking Giant and Future Mysteries
Perhaps one of the most intriguing aspects of the Great Red Spot today is that it’s not the massive storm it once was. In the 21st century, the major diameter of the Great Red Spot has been observed to be shrinking. In 2004 its length was about half that of a century earlier, when it reached a size of 40,000 km (25,000 mi), about three times the diameter of Earth. At the present rate of reduction, it will become circular by 2040. Scientists are witnessing this ancient storm transform before their eyes.
As observed by an amateur astronomer in 2019, it also seems to be “flaking.” It has been shrinking over recent decades. Though it is bigger than Earth, the Great Red Spot is actually shrinking. It continues to shrink at a measurable rate. In 2019, the spot began “flaking” at its edge, with fragments of the storm spinning off and dissipating. This dramatic change raises questions about whether we’re witnessing the death of this centuries-old storm.
The cause of the Great Red Spot’s shrinking remains unknown. Some research has hypothesized that the spot could disappear in a few decades, but because researchers don’t fully understand how and why the spot is changing, it may also last for much longer, possibly many centuries. The uncertainty surrounding its future makes ongoing observation even more crucial.
The Great Red Spot stands as one of nature’s most impressive demonstrations of atmospheric dynamics, showing us what happens when the right conditions allow a storm to persist for centuries rather than days. Its massive size, incredible wind speeds, and mysterious longevity continue to challenge our understanding of planetary weather systems. As this ancient storm slowly shrinks and changes before our eyes, it reminds us that even the most seemingly permanent features in our solar system are constantly evolving. Whether the Great Red Spot will disappear in our lifetimes or continue spinning for centuries more remains one of the most captivating mysteries in planetary science. What do you think about this cosmic giant? Tell us in the comments.
Jan loves Wildlife and Animals and is one of the founders of Animals Around The Globe. He holds an MSc in Finance & Economics and is a passionate PADI Open Water Diver. His favorite animals are Mountain Gorillas, Tigers, and Great White Sharks. He lived in South Africa, Germany, the USA, Ireland, Italy, China, and Australia. Before AATG, Jan worked for Google, Axel Springer, BMW and others.
