Rain of Methane Spotted along Titan’s Equator

March 18th, 2011 at 3:42 am

A group of astronomers has reported that they have observed a rain of methane for the first time over the equatorial region of Titan, the largest moon on Saturn. Although clouds and rain have been spotted on Titan before, rains are only present over the poles and not along the equatorial region

Compared to Earth’s tropical climate along equator, Titan’s equatorial region is covered in dunes and has a generally arid climate. The difference lies on the seasonal swing of the two celestial bodies’ intertropical convergence zone, where winds from the northern and southern hemispheres meet and produce rainfall. While the Earth’s ICZ is confined along the equator, Titan’s slower planetary rotation causes its ICZ to move from pole to pole.

The Cassini’s Imaging Science Subsystem (ISS) detected low-latitude clouds hovering over Titan’s equatorial region for several weeks on September 2010. A month later, Cassini’s ISS observed a darkening on an area spanning about 510,000 square kilometers, most of which lasted until October 29, 2010.

Scientists propose the darkening was most likely caused by a large methane storm that moist the surface, excluding other causes such as volcanic activity or the redistribution of surface material by high-speed winds. The observation may help explain the presence of dry river beds in Titan’s equatorial region.

Source: Ars Technica


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