Cassini spots monstrous ice cloud on Saturn's moon Titan

Photo credits: NASA/JPL-Caltech/Space Science Institute

 Washington: NASA's Cassini spacecraft has spotted a giant new ice cloud in low - to mid-stratosphere of Titan, the largest moon of Saturn.

Cassini had already imaged an impressive cloud hovering over Titan’s south pole at an altitude of about 186 miles (300 kilometers), but that turned out to be just the tip of the iceberg.

The new ice cloud system, which has been found below the stratosphere - peaking at an altitude of about 124 miles (200 kilometers) – is much bigger. It is believed that the new cloud has a low density, similar to Earth’s fog but likely flat on top.

“When we looked at the infrared data, this ice cloud stood out like nothing we’ve ever seen before,” said Carrie Anderson of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It practically smacked us in the face.”

The new monstrous cloud was detected by Cassini’s infrared instrument - the Composite Infrared Spectrometer, or CIRS - which obtains profiles of the atmosphere at invisible thermal wavelengths.

The new findings made near the south pole of Titan add to the evidence that winter comes in like a lion on this moon of Saturn.

For the past few years, Cassini has been catching glimpses of the transition from fall to winter at Titan’s south pole - the first time any spacecraft has seen the onset of a Titan winter.

Because each Titan season lasts about 7-1/2 years on Earth’s calendar, the south pole will still be enveloped in winter when the Cassini mission ends in 2017.

Scientists found that the ice clouds at Titan’s pole don’t form in the same way as Earth’s familiar rain clouds.

The new cloud was found in the lower stratosphere, where temperatures are even colder. The ice particles are made up of a variety of compounds containing hydrogen, carbon and nitrogen.

The size, altitude and composition of the polar ice clouds help scientists understand the nature and severity of Titan’s winter.

“Titan's seasonal changes continue to excite and surprise,” said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Cassini probe has delivered some incredible images as it orbits around the ringed planet, Saturn, including a recent closest-ever pass over icy moon Enceladus.