of Titan early next year.Cassini-Huygens will go into orbit around Saturn in July after a nearly seven-year journey. The mothership will explore Saturn's atmosphere, rings and moons, including Titan on several flybys. Huygens is expected to provide a remarkable and potentially breakthrough look at the unexplored surface of Titan and, scientists hope, reveal in pictures and other data how much Titan resembles the planet Earth in its early years.
Big and smoggy
At 3,200 miles (5,150 kilometers) wide, Titan is Saturn's largest moon. It is the second largest moon in the solar system behind Jupiter's Ganymede. Titan is about 40 percent the diameter of Earth and roughly 50 percent larger than Earth's Moon.
Titan is the only moon with a substantial atmosphere, made mostly of nitrogen, just as is Earth's air.
The air of Titan is also laden with methane, contributing to a smoggy haze of organic molecules that until recent years has prevented any observations of the surface. The methane is continually altered by sunlight, creating hydrocarbons that condense into particulate matter -- or smog.
Radar and other observations have indicated the presence of seas and suggested the moon may experience
the probe will encounter, however. Scientists have said bright glints seen on Titan are consistent with reflections of a hydrocarbon sea. But they can't rule out smooth land features. The first known bright area, seen by the Hubble Space Telescope back in 1994, was about the size of Australia.Given this limited knowledge and the impending arrival of the Huygens probe, astronomers around the world are mounting multiple ground-based efforts to stretch telescoping to its limits and provide as much information as possible over the next few months.
Best looks yet
The fresh images of Titan's surface were made with a new Simultaneous Differential Imager (SDI) on the Very Large Telescope at the European Southern Observatory (ESO) in Chile.
"I'm far too cautious a scientist say these images say absolutely that Titan has hydrocarbon oceans," said Laird Close, who built the camera. "But this does agree with the general jist of the scientific community."
The camera was not designed with Titan as its prime sort of target.
"This camera was invented to look for planets around other stars," Close, of the University of Arizona, told SPACE.com. "But it turns out that it enables you to take pictures of the atmosphere of a moon, too."
Close and his colleagues have passed their maps and other data on to researchers working on the Huygens mission. "It can't hurt to have a good map of Titan," he said.
The Keck Telescope observations also peer through the hydrocarbon haze, but instead of seeing Titan's surface, they were designed to split the atmosphere into several slices. The snapshots were combined into a movie that shows how the atmosphere changes from top to bottom -- exactly what Huygens will see on the way down.
"Before, we could see each component of the haze but didn't know where exactly it was in the stratosphere or the troposphere," said atmospheric chemist Mate Adamkovics, a graduate student at the University of California, Berkeley. "These are the first detailed pictures of the distribution of haze with altitude."
The observations confirm previous findings and refine knowledge of how the haze is distributed.
Haze over Titan's south pole is evident between 19 and 31 miles (30-50 kilometers) altitude and dissipates seasonally in Titan's long year, which lasts about 29.5 Earth-years. Across a broad part of the northern hemisphere, haze is visible high in the stratosphere of Titan, about 93 miles (150 kilometers) up. The stratospheric haze is absent from the southern hemisphere.
The movie is available at
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