This series of images from Cassini shows changes on the surface of Saturn's moon Titan, as the transition to northern spring brings methane rains to the moon's equatorial latitudes. Some of the most significant changes appear within a period of only a couple of weeks.
The brightest objects seen in these images are methane clouds in the troposphere, the lowest part of the atmosphere, which are most visible on the left of panel B, the lower half of panel C, and the right of panel D. Surface features appear in shades of gray. These images show changes (outlined area) along the southern boundary of a dune field near the equator named Belet. Dark Belet occupies most of the top of these images.
The first image in this montage, panel A on the left, was taken early in the Cassini mission on Oct. 22, 2007, and shows how this region had appeared before the storms. The second image, panel B, was taken on Sept. 27, 2010. The huge arrow-shaped cloud is just out-of-frame to the left in panel B. The arrow-shaped cloud was quickly followed by extensive changes on the surface that can be seen in panel C, an image captured on Oct. 14, 2010. These changes cover an area of 500,000 square kilometers (193,000 square miles), roughly the combined area of Arizona and Utah in the United States.
The wet terrain can still be seen about a month after the storm in panel D, which was taken on Oct. 29, 2010. But by Jan. 15, 2011, which was the date of panel E, the area mostly appears dry and bright, with a much smaller area still dark, i.e. wet.
These images were re-projected, and the view in each is centered on terrain at 19 degrees south latitude, 251 degrees west longitude. Images in panels A, B, D, and E were taken with the Cassini spacecraft narrow-angle camera using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The image in panel C was taken with the Cassini wide-angle camera using the same filter. The views were obtained at a range of distances from approximately 211,000 kilometers (131,000 miles) to 1.85 million kilometers (1.15 million miles) from Titan. Scale is about 7 kilometers (4 miles) per pixel in these re-projected images.