‘1,20,000 km wide’: NASA’s Hubble Telescope discovers a horrific storm raging on Saturn
Produced by Tarun Mishra
Produced by Tarun Mishra
NASA’s Hubble Space Telescope (HST) captured a rare planetary storm on Saturn’s equator in November 1990, soon after its launch. The storm, known as the Great White Spot, was the first equatorial storm observed on Saturn since 1933.
Amateur astronomers initially spotted the storm in September 1990, prompting NASA scientists to prioritise observations. The storm covered Saturn’s entire equatorial region, spanning 120,000 km, with visible turbulent cloud masses and organised vortices
Using its Wide Field/Planetary Camera, Hubble recorded the storm over eight orbits on 17 November 1990. The data produced a colour-accurate movie showing a complete rotation of Saturn, offering detailed insights into the storm’s structure.
NASA scientists corrected Hubble’s spherical aberration in the images, refining details down to 700 km (440 miles). The storm displayed a mix of chaotic cloud formations and swirling bands, revealing dynamic atmospheric patterns.
Such storms occur roughly every 20–30 years, influenced by Saturn’s northern hemisphere tilting towards the Sun. Researchers studied wind speeds, cloud composition, and atmospheric triggers to understand these periodic storms.
Studies from Caltech suggest the storm was triggered by atmospheric water vapour cooling and destabilising Saturn’s upper atmosphere. This process released convective energy, leading to the large-scale storm.
The 1990 storm remains a key reference for planetary meteorology. While a similar midlatitude storm occurred in 2010, Saturn’s next equatorial storm is not expected before 2040, making Hubble’s observations critical for future research.