View Full Version : A dark spot on Titan's surface may be a tropical oasis

06-14-12, 03:40 AM
http://cdn.arstechnica.net/wp-content/uploads/2012/06/Titan_surface-640x640.jpg Titan, under the smog. The methane sea known as Kraken Mare is the dark smuge at the top of the image.
NASA/JPL-Caltech/Space Science Institute (http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4422)

Only two bodies in the Solar System are known to have persistent surface liquid: Earth and Saturn's moon Titan. Unlike Earth, Titan's liquid is methane rather than water, and most of the methane is in the moon's thick atmosphere instead of on the surface. Therefore, instead of large oceans, Titan possesses smaller, shallower seas in the polar regions. The equatorial region is marked by sand dunes, similar to fields found on Earth. Studies of Titan's atmosphere show the tropics to be free of precipitation, making it drier than the driest desert on Earth.

However, analysis of Cassini space probe data from 2004 through 2008 may have found as many as five tropical lakes on Titan. Spectral analysis by Caitlin A. Griffith et al. revealed an oval region that absorbs infrared light, an effect consistent with a small lake of liquid methane at least 2 meters deep. They also identified four other candidate lakes, but the data was far less clear. In the absence of rain, the authors suggest the most likely source for these lakes is subsurface‚??making them desert oases.

Mapping Titan's surface is complicated by the moon's thick atmosphere, which is opaque to many wavelengths of light. While Earth's atmosphere has many broad "windows"‚??ranges of wavelengths that can penetrate to the surface, including visible and radio light‚??Titan has much narrower windows in the infrared and radio portions of the spectrum. The Cassini probe and the associated Huygens lander performed detailed chemical analysis of the atmosphere; they found the opacity is due to methane and other hydrocarbons, compounds of hydrogen and carbon responsible for smog on Earth.

Read more (http://arstechnica.com/science/2012/06/a-dark-spot-on-titans-surface-may-be-a-tropical-oasis/) | Comments (http://arstechnica.com/science/2012/06/a-dark-spot-on-titans-surface-may-be-a-tropical-oasis/?comments=1#comments-bar)

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