Image: Two Halves of Titan

Description: Seasonal changes in the atmosphere of Saturn's largest moon are captured in this natural-colour 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-colour 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 infra-red 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 signalled 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 (5150 kilometres across). North on Titan is up. The images were obtained with the Cassini spacecraft wide-angle camera at a distance of approximately 174,000 kilometres from Titan. Image scale is 10 kilometres per pixel.
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