Through the eye of the Hubble Telescope, scientists have recorded a gigantic storm blowing across Saturn at more than 1,000 mph, sending ammonia clouds billowing 150 miles into space.

Pictures taken by the telescope's planetary camera show that the storm, which began in September as an Earth-size white spot, now girdles the planet in a band 6,000 miles across."It might just be the largest atmospheric structure right now in the solar system outside of the sun," Andrew Ingersoll, a planetary scientist from the California Institute of Technology, said Tuesday. "The last time Saturn did anything of this magnitude was in 1933."

After amateur astronomers discovered the white spot in September, the Hubble was trained on Saturn, the second largest planet in the solar system. The flaw in the telescope's mirrors does not detract from the instrument's ability to see such relatively close objects.

By Nov. 9 and 11 when the first pictures were taken, the storm clouds ringed the planet with clearly visible swirls and loops. The Hubble photographed Saturn again last weekend, bringing the number of pictures to 400.

They will be made into a film, said Charles Pellerin, director of astrophysics at NASA headquarters, "and pretty soon we'll be able to watch what some people have called the storm of the century evolve in great detail."

Astronomers don't know what is causing the great white belt of clouds and whether it is diffusing as it spreads or whether material from the planet is feeding it.

"These planets like Jupiter and Saturn are fluid objects, all the way to the center," Ingersoll said. "There are no volcanoes erupting because there are no volcanoes. There is no solid crust. These planets are sort of bubbling cauldrons of liquid and gas."