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While terrestrial storms are fleeting, Jupiter’s Great Red Spot has persisted for centuries, making it the most enduring weather system in our solar system.
Jupiter dominates the planetary family as the largest planet, with a diameter of nearly 140,000 km—about 11 times Earth's. It orbits the Sun at an average distance of 780 million km, roughly five times farther from the Sun than Earth. Unlike Earth, Jupiter is a gas giant, lacking a solid surface for landers. Its atmosphere is primarily hydrogen and helium, and as of 2014 it hosts up to 67 moons. (Ref. 3)
Italian astronomer Giovanni Cassini first recorded the Great Red Spot in the late 17th century. The storm’s existence predates human observation, suggesting it began centuries earlier. (Ref. 2)
About a century ago, the eye‑shaped vortex measured roughly twice its current diameter and has been shrinking steadily. If the current rate continues, the spot may become almost circular by 2040. Whether this shrinkage signals the storm’s end or is a normal fluctuation remains uncertain. (Ref. 2)
In 2014, the Great Red Spot spanned between 16,000 km and 20,000 km, enough to encompass 2.5 to 3 Earths. Scientists attribute its size and longevity to Jupiter’s internal heat and the absence of landmasses—allowing the storm to remain over a “sea” of gas, enhancing stability. The storm’s cloud tops rise about 8 km above surrounding clouds, and two powerful jet streams anchor it latitudinally. (Refs. 1, 2)
The vortex behaves like a colossal hurricane, rotating counter‑clockwise and completing one cycle every six Earth days. Wind speeds at its outer edges can reach 432 km/h (≈270 mph), surpassing any recorded terrestrial winds. (Ref. 2)
Scientists debate the cause of the spot’s distinctive color; the prevailing hypothesis points to high concentrations of phosphorus and sulfur. The hue ranges from deep red at the core to a paler salmon at the periphery. (Ref. 2)
