Recent images of Titan, Saturn's largest moon, bear a striking resemblance to some of the deserts on Earth. The pictures, captured by the Cassini spacecraft as it flew by Titan last October and released today, show sand dunes at Titan's equator much like those in the Sahara desert. "It's bizarre," said Ralph Lorenz of University of Arizona's Lunar and Planetary Laboratory. "These images from a moon of Saturn look just like radar images of Namibia or Arabia." On Earth, all wind is ultimately a result of heat differences produced by sunlight that warms the planet unevenly. Scientists have long assumed...