This Hubble telescope picture of Saturn captures a rare storm that appears as a white arrowhead-shaped feature near the planet's equator. An upwelling of warmer air, similar to a terrestrial thunderhead, generates the storm.

The east-west extent of this storm is equal to the diameter of the Earth (about 7,900 miles). Hubble provides new details about the effects of Saturn's prevailing winds on the storm. These winds shape a dark "wedge" that eats into the left side of the bright central cloud. The new image shows that the storm's motion and size have changed little since its discovery in September 1994.