Astronomy
The Properties of Jupiter's Great Red Spot Storm
Quick fact
The Great Red Spot is a massive anticyclonic storm with wind speeds exceeding 400 mph (640 km/h), and it has been continuously observed for over 350 years, though it is slowly shrinking.
Why this is interesting
You've probably seen Jupiter's Great Red Spot in pictures—a giant crimson eye staring out from the planet's clouds. But did you know it's a storm that has been raging for centuries and is large enough to swallow Earth whole?
Read the full explanation
Understanding The Properties of Jupiter's Great Red Spot Storm
Think of the Great Red Spot as a hurricane that never ends, but on a planet with no solid surface. It is not a feature of the ground—it is a giant swirling vortex in Jupiter's cloud tops. The storm is so wide that Earth could fit entirely inside it. It spins slowly, taking about six Earth days to complete one rotation, but in that spin, it stirs clouds of ammonia crystals and other chemicals. The spot is actually a high-pressure region, meaning air in its center is forced downward, unlike typical low-pressure storms on Earth. This downward motion keeps the clouds clear and gives the spot its sharp, oval shape. The red color likely comes from compounds rising from deeper layers of Jupiter's atmosphere, perhaps organic molecules or phosphorus compounds, which are altered by sunlight and cosmic radiation.
A deeper explanation
Why does this storm persist? Jupiter rotates very fast, once every 9.9 hours, generating a powerful Coriolis effect that corrals the planet's atmospheric flows into strong east-west jet streams. The Great Red Spot sits between two opposing jet streams, acting like a giant spinning gear caught between conveyor belts. It is an anticyclone: a region of high pressure where the air rotates in the opposite direction to a cyclone (Earth's hurricanes, for example). This rotation, combined with Jupiter's internal heat rising from below, continuously feeds the vortex with energy. Unlike Earth's storms, which break apart when they hit land or encounter wind shear, the Great Red Spot has nothing to slow it down—Jupiter's atmosphere is deep, turbulent, and without friction from a planetary surface. The storm is also stable because it is large enough that smaller storms merge into it, delivering energy instead of disrupting it. Understanding why this spot has survived for centuries helps scientists model fluid turbulence and atmospheric dynamics not just on Jupiter, but also on other gas giants and in ocean currents on Earth.