Washington, Oct 12 : New infrared images from the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT) in Chile, and the NASA’s WM Keck Observatory in Hawaii, has shown drizzle of methane over the western foothills of Titan’s major continent Xanadu.

In most of the Keck and VLT images, liquid methane clouds and drizzle appear at the morning edge of Titan, the arc of the moon that has just rotated into the light of the Sun.

“Titan's topography could be causing this drizzle. The rain could be caused by processes similar to those on Earth: moisture laden clouds pushed upslope by winds condense to form a coastal rain,” said Imke de Pater, member of the team that made the discovery.

Lead author Máté Ádámkovics said only areas near Xanadu exhibited morning drizzle, but not always in the same spot.

“Depending on conditions, the drizzle could hit the ground or turn into a ground mist. The drizzle or mist seems to dissipate after local mid-morning, which since Titan takes 16 Earth days to rotate once, is about three Earth days after sunrise,” he said.

“Maybe only Xanadu has misty mornings,” he said.

Separately, the NASA/ESA/ASI Cassini spacecraft has provided new views of hydrocarbon lakes and seas on Saturn’s moon Titan.

The newly assembled radar images from the Cassini spacecraft has provided views of the hydrocarbon lakes and seas on the north pole of Titan, while a new radar image has revealed that Titan's south polar region also has lakes.

The southern region images were beamed back after an Oct. 2 flyby in which a prime goal was the hunt for lakes at the south pole.

Rosaly Lopes, Cassini radar scientist at NASA's Jet Propulsion Laboratory, Pasadena, California, said, approximately 60 percent of Titan's north polar region above 60 degrees latitude had been mapped by Cassini's radar instrument.

She said about 14 percent of the mapped region was covered with what scientists interpreted as liquid hydrocarbon lakes.

Lopes said, a mosaic image, created by stitching together radar images from seven Titan flybys over the last year and a half, had shown the north pole pitted with giant lakes and seas, at least one of them larger than Lake Superior.

“This is our version of mapping Alaska, the northern parts of Canada, Greenland, Scandinavia and Northern Russia. It's like mapping these regions of Earth for the first time,” she said.

She said the lakes and seas were very common at the high northern latitudes of Titan, where it was winter now.

“It rains methane and ethane there, filling the lakes and seas. These liquids also carve meandering rivers and channels on the moon's surface,” she said.

She said now Cassini was moving into unknown territory, the south pole of Titan.

“We wanted to see if there are more lakes present there and, sure enough, there they are, three little lakes smiling back at us. Titan is indeed the land of lakes and seas,” said Lopes.

“It will be interesting to see the differences between the north and south polar regions. It is now summer at Titan's south pole. A season on Titan lasts nearly 7.5 years, one quarter of a Saturn year, which is 29.5 years long. Monitoring seasonal change helps scientists understand the processes at work there,” she said.

She said scientists were making progress in understanding how the lakes could have formed.

She said, on Earth, lakes either filled low spots or were created when the local topography intersected a groundwater table. The depressions containing the lakes on Titan might have formed by volcanism or by a type of erosion (called karstic) of the surface, leaving a depression where liquids can accumulate. Karstic lakes are common on Earth, she said.

“The lakes we are observing on Titan appear to be in varying states of fullness, suggesting their involvement in a complex hydrologic system akin to Earth's water cycle. This makes Titan unique among the extra-terrestrial bodies in our solar system,” said Alex Hayes, a graduate student who studies Cassini radar data at the California Institute of Technology in Pasadena.

“The lakes we have seen so far vary in size from the smallest observable, approximately 1 square kilometre (0.4 square miles), to greater than 100,000 square kilometres (40,000 square miles), which is slightly larger than the Great Lakes in the Midwestern US,” Hayes added.

“Of the roughly 400 observed lakes, 70 percent of their area is taken up by large ‘seas’ greater than 26,000 square kilometres (10,000 square miles),” he said. (ANI)