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Great Red Spot

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The Great Red Spot is a massive, high-pressure storm on the planet Jupiter. It is an anticyclone, which is a type of storm that rotates around a center of high pressure. This storm is the largest anticyclonic storm in our entire Solar System. It is located 22 degrees south of Jupiter's equator. The storm is famous for its distinct red-orange color. Scientists are still researching the exact origin of this color.

Jupiter - Great Red Spot - PJ7-60 61 62 - Balanced (49803032983)
Jupiter - Great Red Spot - PJ7-60 61 62 - Balanced (49803032983)

The storm functions through complex mechanical dynamics. It rotates in a counterclockwise direction. As of 2008, it completes one full rotation every 4.5 Earth days. This is also known as 11 Jovian days. The storm is held in place by powerful winds. A modest eastward jet stream sits to its south. A very strong westward jet stream sits to its north. These winds confine the storm to its specific area. While edge winds can peak at 680 kilometers per hour, the internal currents seem stagnant. This means there is very little inflow or outflow inside the vortex.

Winds in Jupiter’s Great Red Spot
Winds in Jupiter’s Great Red Spot

Because Jupiter is a gas giant, the storm behaves differently than storms on Earth. On Earth, land creates friction that slows storms down. Jupiter has no solid planetary surface to cause such friction. It only has a mantle of hydrogen. This lack of surface allows atmospheric eddies to persist. They continue to spin because nothing opposes their angular momentum. The storm's cloud tops are about 8 kilometers above the surrounding clouds. Infrared data shows the core is colder than other clouds. This indicates the storm is high in altitude.

Jupiter Great Red Spot Elger November 1881
Jupiter Great Red Spot Elger November 1881

History shows that observing this storm is a long-term challenge. Robert Hooke described a spot on Jupiter in May 1664. Giovanni Cassini observed a permanent spot from 1665 to 1713. However, a 2024 study suggests these might not be the same storm. The older spot had a different rotation and location. The modern Great Red Spot has been frequently observed since September 5, 1831. It gained massive popularity after a prominent appearance in 1879. Since then, astronomers have maintained continuous observations.

Le osservazioni astronomiche - Giove
Le osservazioni astronomiche - Giove

Recent data from spacecraft has revealed much about the storm's scale. In 1979, Voyager 1 transmitted the first detailed images. These images showed cloud details as small as 2 kilometers across.

Great Red Spot From Voyager 1
Great Red Spot From Voyager 1

The storm is currently shrinking in size. In 1900, its length was about 24,000 kilometers. At that time, it was three times the diameter of Earth.

Jupiter, Earth size comparison
Jupiter, Earth size comparison

By 2004, its length was about half of that size. Today, the spot is 1.3 times the diameter of Earth. It is becoming more circular and may be a perfect circle by 2040.

Scientists are also studying the storm's immense depth. The Juno spacecraft provided new insights during its 2016 mission. In 2017, Juno used a Microwave Radiometer to scan the storm. These scans suggest the vertical depth reaches 300 to 500 kilometers below the cloud level. In this deep region, the atmospheric pressure drops to about 10 bars. The storm's winds actually increase in speed as they go deeper. They reach 50% of their cloud-level velocity before the wind begins to decay. This decay happens at lower levels within the atmosphere.

The Great Red Spot also influences the temperature of Jupiter's atmosphere. Turbulence from the storm creates acoustic waves. These waves rise vertically up to 400 kilometers above the storm. When these waves break in the upper atmosphere, they convert energy into heat. This process makes the upper atmosphere several hundred kelvins warmer than the rest of the planet. This is similar to how ocean waves crash on a beach.

This heating helps explain why the upper atmosphere is so much hotter than other regions.

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🖼️ Images & Media (9)
File:Jupiter - Great Red Spot - PJ7-60 61 62 - Balanced (49803032983).png
Jupiter - Great Red Spot - PJ7-60 61 62 -...
File:Le osservazioni astronomiche - Giove.jpg
Le osservazioni astronomiche - Giove.jpg
File:Jupiter Great Red Spot Elger November 1881.png
Jupiter Great Red Spot Elger November 1881.png
File:Great Red Spot From Voyager 1.jpg
Great Red Spot From Voyager 1.jpg
File:Jupiter GRS Changes.png
Jupiter GRS Changes.png
File:790106-0203 Voyager 58M to 31M reduced.gif
790106-0203 Voyager 58M to 31M reduced.gif
File:Jupiter, Earth size comparison.jpg
Jupiter, Earth size comparison.jpg
File:Telescopes and Spacecraft Join Forces to Probe Deep into Jupiter's Atmosphere (49892941386).png
Telescopes and Spacecraft Join Forces to...
File:Winds in Jupiter’s Great Red Spot.jpg
Winds in Jupiter’s Great Red Spot.jpg
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