Facts about Jupiter’s Great Red Spot and images of the centuries-old cyclone.

By Lee Dyson

Published: Thursday, 16 November 2023 at 14:51 PM

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Jupiter’s Great Red Spot is a huge storm in Jupiter’s Southern Hemisphere that’s about 1.3 times as wide as planet Earth.

It is a giant oval storm of whirling clouds that travel anticlockwise, with wind speeds reaching up to 680 kilometres per hour: much faster than any of Earth’s storms.

The Great Red Spot is Jupiter’s most famous feature, a vast storm that has been observed continuously for almost 200 years and was probably first spotted in 1665.

Sitting on the edge of Jupiter’s South Equatorial Belt, the Great Red Spot is confined between a strong westward jet stream to its north and a weaker eastbound one to its south.

Winds along the edge can exceed 430km/h as it spins counter-clockwise (turning once every six Earth days), but the central eye of the storm seems largely stagnant.

While most of Jupiter’s darker features are lower- lying than the pale clouds of the zones, the top of the Great Red Spot soars to 8km above its surroundings.

The Great Red Spot changes colour and occasionally disappears from view altogether.

The source of the Great Red Spot’s colour (which can vary from intense red to a salmony-pink and sometimes disappears completely, leaving just a ‘hollow’ in the surrounding weather systems to reveal
the spot’s presence) is still unknown.

However, most scientists believe it is created by chemicals welling up from deep inside the planet and perhaps undergoing reactions on exposure to sunlight.

NASA Juno and the Great Red Spot

In 2019, Juno made two low passes over the spot, allowing scientists to probe beneath the surface by looking for slight deflections in the probe’s path caused by concentrations of mass (and higher gravity) in the region.

These confirmed that the Great Red Spot probably extends to 300km beneath the cloud tops.

Scientists got their best ever look at the storm when NASA’s Juno spacecraft flew over the Great Red Spot on 10 July 2017.

During the flyover, Juno passed about 9,000 km above the Great Red Spot’s cloud tops.

Data collected by NASA’s Juno spacecraft has revealed that the Great Red Spot penetrates at least 320km down into Jupiter’s atmosphere. That’s over 30 times deeper than the deepest point of Earth’s oceans.

Want to explore the Great Red Spot for yourself? Read our guide on how to observe Jupiter through a telescope

How old is the Great Red Spot?

The Great Red Spot is known to have been raging for centuries, having been observed by astronomers for over 300 years.

Astronomers Robert Hooke and Giovanni Cassini are known to have observed and recorded a feature located on Jupiter at the Great Red Spot’s latitude, suggesting they may have also observed the huge cyclone.

But the first confirmed sighting of the Great Red Spot is thought to have been by German amateur astronomer Samuel Heinrich Schwabe in 1831.

How big is the Great Red Spot?

Observations of the Great Red Spot have shown that it is shrinking over time.

The Voyager spacecraft recorded the width of the Great Red Spot as around 25,000km in 1979 – about twice the diameter of Earth – and it’s now thought to have shrunk to 16,000km, as of April 2017.

Data from ground-based telescopes reveals that the Great Red Spot has reduced in width by a third and height by one eighth since the time of the Voyagers’ fly-by.

Pictures of the Great Red Spot

There are plenty of amazing images of the Great Red Spot captured by the Juno spacecraft and the Hubble Space Telescope over the years.

Below is a selection of images of the Jovian storm captured by astrophotographers and BBC Sky at Night Magazine readers.

For advice on capturing images of Jupiter yourself, read our guide on how to photograph the planets.

And don’t forget to send us your images or share them with us via Facebook, Twitter and Instagram.

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