Nav: Home

In a cosmic hit-and-run, icy Saturn moon may have flipped

May 31, 2017

ITHACA, N.Y. - Enceladus - a large icy, oceanic moon of Saturn - may have flipped, the possible victim of an out-of-this-world wallop.

While combing through data collected by NASA's Cassini mission during flybys of Enceladus, astronomers from Cornell University, the University of Texas and NASA have found the first evidence that the moon's axis has reoriented, according to new research published in Icarus.

Examining the moon's geological features, the group showed how Enceladus appears to have tipped away from its original axis by about 55 degrees.

"We found a chain of low areas, or basins, that trace a belt across the moon's surface that we believe are the fossil remnants of an earlier, previous equator and poles," said lead author Radwan Tajeddine, research associate in Cornell's Department of Astronomy and a Cassini imaging team associate. "Their pattern reflects spatial variations in the icy shell, consistent with a variety of geological features visible in Cassini images."

At the moon's current southern end, active jets discharge water vapor (as well as organic compounds, gases, salts and silica) through vents from an ocean deep beneath the moon's icy-crust surface. It's a place technically known as the south polar terrain, and astronomers have nicknamed the long, geologically active fractures "Tiger Stripes" - each about 80 miles long and a little over a mile wide.

Tajeddine believes an asteroid may have struck the moon's current south polar region when it was closer to the equator in the past. "The geological activity in this terrain is unlikely to have been initiated by internal processes," he said. "We think that, in order to drive such a large reorientation of the moon, it's possible that an impact was behind the formation of this anomalous terrain."

Wobbly, rickety and unsteady after an asteroid's smack, the physics of Enceladus' rotation would have eventually re-established stability, a process that likely took over a million years. To do that, the north-south axis needed to change - a mechanism called "true polar wander."

Enceladus' topographic and geological features can be explained through geophysical processes, but the moon's north and south poles are quite different. The south is active and geologically young, while the north is covered in craters and appears much older.

"The differences Cassini has observed between the north and south poles remains peculiar," Tajeddine said. "Originally, the poles of Enceladus would have been the same, more or less, before true polar wander occurred. The true polar wander hypothesis seems very plausible when we take a combined look at the patterns of highs and lows across the moon's surface, the physical appearance of surface features and the differences between the current poles."
-end-
Other authors of the research, which posted online April 30 and will officially publish July 1, 2017, "True Polar Wander of Enceladus From Topographic Data," are Cornell's Joseph Burns, the Irving Porter Church Professor of Engineering and professor of astronomy; Peter C. Thomas, visiting scientist; and Paul Helfenstein, senior research associate; and Krista M. Soderlund, University of Texas at Austin; Matthew M. Hedman, University of Idaho; and Paul M. Schenk, Lunar and Planetary Institute, Houston. The research was funded by NASA.

Cornell University

Related Saturn Articles:

Saturn surpasses Jupiter after the discovery of 20 new moons
Move over Jupiter; Saturn is the new moon king. A team led by Carnegie's Scott S.
New SwRI study argues that Saturn's rings are actually not young
No one knows for certain when Saturn's iconic rings formed, but a new study co-authored by a Southwest Research Institute scientist suggests that they are much older than some scientists think.
Hubble reveals latest portrait of Saturn
The NASA/ESA Hubble Space Telescope's Wide Field Camera 3 observed Saturn on 20 June 2019 as the planet made its closest approach to Earth this year, at approximately 1.36 billion kilometres away.
Saturn's rings shine in Hubble's latest portrait
Saturn is so beautiful that astronomers cannot resist using the Hubble Space Telescope to take yearly snapshots of the ringed world when it is at its closest distance to Earth.
Saturn's moon Mimas, a snowplough in the planet's rings
The Solar System's second largest planet both in mass and size, Saturn is best known for its rings.
More Saturn News and Saturn Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...