Skywatch

  • September 29, 2005

    Episode 3: Titan's Methane Lake

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    It might be a lake, but you wouldn't want to vacation nearby. Titan, the largest of Saturn's 34 known moons, could have a lake of liquid methane on its surface. Titan, a moon bigger than the planets Mercury and Pluto, has its own atmosphere. NASA's Cassini mission, which has been orbiting Saturn for more than a year, sent out a probe, called Huygens, to Titan's surface. The probe sent images back as it descended. The images show a feature near Titan's south pole that looks like a lake of approximately 145 miles by 45 miles. It has a smooth shoreline and is reminiscent of Earth's lake shores. The region has methane clouds, so if the feature is a lake, it could have been formed by methane raining onto the surface. The next step is to see if the surface of the "lake" is liquid. Without landing there, how can researchers find this out? One idea is to search for reflections off of the surface of the feature, like the glare of sunlight from a water lake on Earth.