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Infrared-bright Spot on Titan
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Infrared-bright Spot on Titan

November 17, 2009
The visual and infrared mapping spectrometer instrument onboard Cassini has found an unusual bright, red spot on Titan.

This dramatic colour (but not true colour) image was taken during the 16 April 2005, encounter with Titan. North is to the right. In the centre it shows the dark lanes of the "H"-shaped feature discovered from Earth and first seen by Cassini last July shortly after it arrived in the Saturn system. At the southwestern edge of the "H" feature, near Titan's limb (edge), is an area roughly 500 kilometres (300 miles) across. That area is 50 percent brighter, when viewed using light with a wavelength of 5 μm, than the bright continent-sized area known as Xanadu.

Xanadu extends to the northwest of the bright spot, beyond the limb (edge) of Titan in this image. Near the terminator (the line between day and night) at the bottom of this image is the 80 kilometre (50 mile) crater that has been previously seen by the Cassini radar, imaging cameras, and the visual and infrared spectrometer.

At wavelengths shorter than 5 μm, the spot is not unusually bright. The strange spectral character of this enigmatic feature has left the team with four possibilities for its source: the spot could be a surface colouration, a mountain range, a cloud, or a hot spot.

The hot spot hypothesis will be tested during a Titan flyby on 2 July 2006, when the visual and infrared spectrometer will take nighttime images of this area. If it is hot, it will glow at night.

This colour image was created from separate images in the 1.7 μm (blue), 2.0 μm (green), and 5.0 μm (red) spectral windows through which it is possible to see Titan's surface. The yellow that humans see has a wavelength of about 0.5 μm, so the colours shown are between 3 and 10 times more red than the human eye can detect.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.