October 16, 2009
Seasonal changes in the atmosphere of Saturn's largest moon are captured in this natural color image, which shows Titan with a slightly darker top half and a slightly lighter bottom half.
Titan's atmosphere has a seasonal hemispheric dichotomy, and this image was taken shortly after Saturn's August 2009 equinox. Images taken using red, green and blue spectral filters were combined to create this natural color view. Scientists have found that the winter hemisphere typically appears to have more high-altitude haze, making it darker at shorter wavelengths (ultraviolet through blue) and brighter at infrared wavelengths. The switch between dark and bright occurred over the course of a year or two around the last equinox. Scientists are studying the mechanism responsible for this change, and will monitor the dark-light difference as it flip-flops now that the 2009 equinox has signaled the coming of spring and then summer in the northern hemisphere.
Although this hemispheric boundary appears to run directly east-west near the equator, its position is not level with latitude and is actually offset from the equator by about 10 degrees of latitude.
This view looks toward the Saturn-facing side of Titan (5,150 kilometers, or 3200 miles across). North on Titan is up.
The images were obtained with the Cassini spacecraft wide-angle camera on Aug. 25, 2009 at a distance of approximately 174,000 kilometers (108,000 miles) from Titan. Image scale is 10 kilometers (6 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
Credit: NASA/JPL/Space Science Institute