Great Red Spot
Imagine a swirling whirlpool in a drained bathtub, except it is bigger than Earth and has been spinning endlessly for hundreds of years.
Definition The Great Red Spot is a colossal, reddish anticyclonic storm churning in Jupiter's southern hemisphere for centuries. Spanning wider than Earth itself, it has survived for so long thanks to Jupiter's lack of a solid surface and powerful surrounding jet streams.
A Giant Red Eye Staring from Jupiter
Think of the violent vortex that forms when you pull the plug in a full bathtub. On Jupiter's surface, a storm just like that stretches across planetary proportions. When looking through a telescope, the vivid crimson dot nestled in its southern hemisphere is the Great Red Spot.
This tempest is impossibly vast. In its prime, it could have easily swallowed three Earths side by side, and even after shrinking over time, it can still fit our entire planet inside with room to spare. Along the storm's outer edges, fierce howling winds blast continuously at speeds between 400 and 600 kilometers per hour (250 to 370 mph).
While even the most destructive hurricanes on Earth run out of steam and dissipate in days or weeks, the Great Red Spot has been spinning without a single break for centuries, ever since humans first observed it through telescopes in the 17th century.
Why Hasn't It Vanished After Hundreds of Years?
Hurricanes on Earth feed on warm ocean moisture, but they weaken dramatically the moment they make landfall. That's because friction against the solid ground swiftly drains the storm of its rotational energy.
Jupiter, however, is a gas giant with no solid crust to stand on. There are no continents, mountains, or rocky obstacles beneath the storm to generate friction and slow it down. Because the storm never trips over solid ground, its energy remains remarkably preserved.
On top of that, Jupiter features intense atmospheric jet streams flowing in opposite directions along its colorful bands. The jet streams running above and below the Great Red Spot push against it like two hands rubbing and spinning a top, continuously feeding rotational energy into the vortex.
Looking a Little Closer
To be more precise, the Great Red Spot is not a low-pressure system where air rushes inward; it is an anticyclone with higher atmospheric pressure than its surroundings. Rising air in its center gets pushed outward, driving a massive counterclockwise rotation in Jupiter's southern hemisphere.
Why is it red? Scientists believe chemical reactions in the atmosphere are responsible. Compounds like ammonia and hydrogen sulfide from deep within the planet are lifted high into the upper atmosphere by strong updrafts. There, exposure to solar ultraviolet light breaks them down into compounds that glow red and orange.
Recent data from spacecraft and telescopes reveal that the Great Red Spot has been shrinking over the past century, turning from an oval into a rounder shape. While its width has contracted, its vertical depth remains thick and towering, making the future of this legendary monster storm one of the most exciting questions in modern planetary science.
๐ค Common misconceptions
The Great Red Spot is a giant red rocky mountain or landmass on Jupiter's surface.
Jupiter is a gas giant with no solid surface at all. The Great Red Spot is not land, but a gargantuan gaseous storm vortex swirling in the atmosphere for centuries.
๐งบ Where you meet it
The Great Red Spot is Jupiter's colossal anticyclonic storm that has churned for centuries, sustained by the absence of surface friction and energizing jet streams.