THE Cassini spacecraft has found a giant methane-spewing volcano on Saturn鈥檚 moon Titan.
Before Cassini, the methane in Titan鈥檚 atmosphere was taken as evidence that there must be oceans of liquid methane to replenish it in the air. However, both the Cassini orbiter and the Huygens probe, which landed on Titan in January, saw no reflections from the moon鈥檚 surface that would be typical of liquid surfaces, virtually ruling out oceans of methane.
Now, Cassini鈥檚 infrared camera has peered through Titan鈥檚 hazy atmosphere and spotted a large dome-like structure, 30 kilometres across. Christophe Sotin of the University of Nantes in France and his colleagues have analysed the images and say the dome is an ice volcano produced by a rising plume of hydrocarbon ices (Nature, vol 435, p 786). Such low-temperature volcanism could be a significant source of methane on Titan, says Sotin.
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