NASA-International Space Station: Scientists Elucidate Mystifying Lake Asymmetry on Titan

Scientists Elucidate Mystifying Lake Asymmetry on Titan

Researchers at the California Institute of Technology, NASA's Jet Propulsion Laboratory, and other institutions propose that the eccentricity of Saturn's orbit around the sun may be accountable for the unusually uneven distribution of lakes over the northern and southern polar regions of the planet's largest moon, Titan

As revealed by Synthetic Aperture Radar imaging data from NASA's Cassini spacecraft, liquid methane and ethane lakes in Titan's northern high latitudes cover 20 times additional area than lakes in the southern high latitudes. The Cassini data also show that there are significantly more partially filled and now-empty lakes in the north. The asymmetry is not likely to be a statistical fluke because of the big amount of data collected by Cassini in its five years surveying Saturn and its moons.

Scientists initially considered the idea that "there is something intrinsically different about the northern polar region versus the south in stipulations of topography, such that liquid rains, drains or infiltrates the ground more in one hemisphere," said Oded Aharonson of Caltech, lead author of the Nature Geoscience paper.

Like Earth and other planets, Saturn's orbit is not completely circular, but is instead somewhat elliptical and oblique. Because of this, during its southern summer, Titan is about 12 percent nearer to the sun than during the northern summer. As a result, northern summers are extensive and subdued; southern summers are short and extreme.

"Like Earth, Titan has tens-of-thousands-of-year variations in climate driven by orbital motions," Aharonson said. On Earth, these variations, well-known as Milankovitch cycles, are associated to changes in solar radiation, which concern global redistribution of water in the form of glaciers, and are believed to be responsible for ice-age cycles. "On Titan, there are long-term climate cycles in the worldwide movement of methane that make lakes and carve lake basins. In both cases we discover a record of the process embedded in the geology," he added.

"We may have established an example of long-term climate change, similar to Milankovitch climate cycles on Earth, on another object in the solar system," he said.

Posted by CuttsMatt | at 9:25 PM