* Astronomy

Titanic Jigsaw Challenge:  Piecing together a global colour map of Saturns largest moon

An international team led by the University of Nantes has pieced together images gathered over six years by the Cassini mission to create a global mosaic of the surface of Titan. The global maps and animations of Saturn's largest moon are being presented by Stéphane Le Mouélic at the EPSC-DPS Joint Meeting 2011 in Nantes, France on Tuesday 4th October.
The team has compiled all the infrared images acquired by the Visual and Infrared Mapping Spectrometer (VIMS) during Cassini's first seventy flybys of Titan. Fitting the pieces of the puzzle together is a painstaking task.  The images must be corrected for differences in the illuminating conditions and each image is filtered on a pixel-by-pixel basis to screen out atmospheric distortions. Titan is veiled by a thick, opaque atmosphere composed mainly of nitrogen.  It has clouds of methane and ethane and there is increasing evidence for methane rain. Only a few specific infrared wavelengths can penetrate the cloud and haze to provide a window down to Titan's surface. An exotic frozen world with many Earth-like geological features has progressively emerged from darkness.
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Updated maps of Titan, consisting of data from the Cassini imaging science subsystem and images dating from April 2004 through August 2008. The image resolutions vary from a few metres to a few tens of kilometres per pixel.


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Credit: NASA/JPL/Space Science Institute

The coloured lines in the polar portions of these maps illustrate the boundaries between surface regions having different albedos which Cassini scientists have interpreted as potential shorelines. Blue outlines indicate features that changed between observations made one year apart.
Brightness variations are due to differences in surface albedo rather than topographic shading.

The IAU has approved three new names for Titan surface features.
Two of the "seas" near Titan's north pole have been named Kraken Mare and Ligeia Mare, and the large island in the northern part of Kraken Mare has been named Mayda Insula.

This global digital map of Titan was created using images taken by the Cassini spacecraft imaging science subsystem.


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Credit: NASA/JPL/Space Science Institute

The images were taken using a filter centred at 938 nanometers, allowing researchers to examine albedo (or inherent brightness) variations across the surface of Titan. Due to the scattering of light by Titan's dense atmosphere, no topographic shading is visible in these images.
The map is an equidistant projection and has a scale of 4 kilometres per pixel. Actual resolution varies greatly across the map, with the best coverage (close to the map scale) near the centre and edges of the map and the worst coverage on the trailing hemisphere (centred around 270 degrees west longitude).