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Saturn and Its Largest Moon Reflect Their True Colors

September 3, 2012 Leave a comment

ScienceDaily (Aug. 29, 2012) — Posing for portraits for NASA’s Cassini spacecraft, Saturn and its largest moon, Titan, show spectacular colors in a quartet of images being released today. One image captures the changing hues of Saturn’s northern and southern hemispheres as they pass from one season to the next.

Colorful Colossuses and Changing Hues: A giant of a moon appears before a giant of a planet undergoing seasonal changes in this natural color view of Titan and Saturn from NASA’s Cassini spacecraft. (Credit: NASA/JPL-Caltech/SSI)
 
 

A wide-angle view in today’s package captures Titan passing in front of Saturn, as well as the planet’s changing colors. Upon Cassini’s arrival at Saturn eight years ago, Saturn’s northern winter hemisphere was an azure blue. Now that winter is encroaching on the planet’s southern hemisphere and summer on the north, the color scheme is reversing: blue is tinting the southern atmosphere and is fading from the north.

The other three images depict the newly discovered south polar vortex in the atmosphere of Titan, reported recently by Cassini scientists. Cassini’s visible-light cameras have seen a concentration of yellowish haze in the detached haze layer at the south pole of Titan since at least March 27. Cassini’s visual and infrared mapping spectrometer spotted the massing of clouds around the south pole as early as May 22 in infrared wavelengths. After a June 27 flyby of the moon, Cassini released a dramatic image and movie showing the vortex rotating faster than the moon’s rotation period. The four images being released today were acquired in May, June and July of 2012.

Read more: http://www.sciencedaily.com/releases/2012/08/120829191639.htm

 

Cassini sees tropical lakes on Saturn moon


June 15, 2012
Scientists had thought that Titan simply had extensive dunes at the equator and lakes at the poles, but now they know that Titan is more complex than previously thought.
by Jet Propulsion Laboratory, Pasadena, California, NASA Headquarters, Washington, D.C.
Saturn’s rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe. Image Credit: NASA/JPL-Caltech/Space Science Institute
NASA’s Cassini spacecraft has spied long-standing methane lakes, or puddles, in the “tropics” of Saturn’s moon Titan. One of the tropical lakes appears to be about half the size of Utah’s Great Salt Lake, with a depth of at least 3 feet (1 meter).The result, which is a new analysis of Cassini data, is unexpected because models had assumed the long-standing bodies of liquid would only exist at the poles.

Where could the liquid for these lakes come from? “A likely supplier is an underground aquifer,” said Caitlin Griffith from the University of Arizona in Tucson. “In essence, Titan may have oases.”

Understanding how lakes or wetlands form on Titan helps scientists learn about the moon’s weather. Like Earth’s hydrological cycle, Titan has a “methane cycle,” with methane rather than water circulating. In Titan’s atmosphere, ultraviolet light breaks apart methane, initiating a chain of complicated organic chemical reactions. But existing models haven’t been able to account for the abundant supply of methane.

“An aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted,” Griffith said. “Methane is a progenitor of Titan’s organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life.”

Global circulation models of Titan have theorized that liquid methane in the moon’s equatorial region evaporates and is carried by wind to the north and south poles, where cooler temperatures cause methane to condense. When it falls to the surface, it forms the polar lakes. On Earth, water is similarly transported by the circulation, yet the oceans also transport water, thereby countering the atmospheric effects.

The latest results come from Cassini’s visual and infrared mapping spectrometer, which detected the dark areas in the tropical region known as Shangri-La, near the spot where the European Space Agency’s Huygens probe landed in 2005. When Huygens landed, the heat of the probe’s lamp vaporized some methane from the ground, indicating it had landed in a damp area.

Areas appear dark to the visual and infrared mapping spectrometer when liquid ethane or methane is present. Some regions could be ankle-deep puddles. Cassini’s radar mapper has seen lakes in the polar region but hasn’t detected any lakes at low latitudes.

The tropical lakes detected by the visual and infrared mapping spectrometer have remained since 2004. Only once has rain been detected falling and evaporating in the equatorial regions, and only during the recent expected rainy season. Scientists therefore deduce that the lakes could not be substantively replenished by rain.

“We had thought that Titan simply had extensive dunes at the equator and lakes at the poles, but now we know that Titan is more complex than we previously thought,” said Linda Spilker from NASA’s Jet Propulsion Laboratory in Pasadena, California. “Cassini still has multiple opportunities to fly by this moon going forward, so we can’t wait to see how the details of this story fill out.”

http://www.jpl.nasa.gov/news/news.cfm?release=2012-172