Astronomy Picture of the Day

Explanation: These tantalizing panoramas follow a remarkable giant storm encircling the northern hemisphere of ringed planet Saturn. Still active, the roiling storm clouds were captured in near-infrared images recorded by the Cassini spacecraft on February 26 and stitched into the high resolution, false-colour mosaics. Seen late last year as a prominent bright spot by amateur astronomers when Saturn rose in predawn skies, the powerful storm has grown to enormous proportions. Its north-south extent is nearly 15,000 kilometres and it now stretches completely around the gas giant's northern hemisphere some 300,000 kilometres. Taken about one Saturn day (11 hours) apart, the panoramas show the head of the storm at the left and cover about 150 degrees in longitude. Also a source of radio noise from lightning, the intense storm may be related to seasonal changes as Saturn experiences northern hemisphere spring.