Saturn's Rings Show Evidence of a Modern-Day Collision

Oct 11, 2006
Saturn's Rings Show Evidence of a Modern-Day Collision
Saturn's D ring--the innermost of the planet's rings--sports an intriguing structure that appears to be a wavy, or "vertically corrugated," spiral. Image credit: NASA/JPL/Space Science Institute.

Scientists with NASA's Cassini mission have spied a new, continuously changing feature that provides circumstantial evidence that a comet or asteroid recently collided with Saturn's innermost ring, the faint D ring.

Imaging scientists see a structure in the outer part of the D ring that looks like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). An observation made by NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its interval was then 60 kilometers (37 miles). Unlike many features in the ring system that have not changed over the last few decades, the interval of this pattern has been decreasing over time.

These findings are being presented today at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Pasadena, Calif.

"This structure in the D ring reminds us that Saturn's rings are not eternal, but instead are active, dynamical systems, which can change and evolve," said Dr. Matt Hedman, Cassini imaging team associate at Cornell University, Ithaca, N.Y.

When Cassini researchers viewed the D ring along a line of sight nearly parallel to the ringplane, they observed a pattern of brightness reversals: a part of the ring that appears bright on the far side of the rings appeared dark on the near side of the rings, and vice versa.

This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material.

Both the changes over time and the "corrugated" structure of this region could be explained by a collision of a comet or meteoroid into the D ring, which then kicked out a cloud of fine particles. This cloud might have inherited some of the tilt of the colliding object's path as it slammed into the rings. An alternate explanation could be that the object struck an already inclined moonlet, shattering it to bits and leaving its debris in an inclined orbit.

In either case, the researchers speculate the aftermath of such a collision would be a ring slightly tilted relative to Saturn's equatorial plane. Over a period of time, as the inclined orbits of the ring particles evolve, this flat sheet of material would become a corrugated spiral that appears to wind up like a spring over time, which is what was observed.

Based on observations between 1995 and 2006, scientists reconstructed a timeline and estimated that the collision occurred in 1984.

Source: NASA

Explore further: Short, sharp shocks let slip the stories of supernovae

Related Stories

Exposing breast cancer using nanoscale polymers

May 13, 2015

Photoacoustic imaging is a ground-breaking technique for spotting tumors inside living cells with the help of light-absorbing compounds known as contrast agents. A*STAR researchers have now discovered a way ...

Molecular chaperones help with folding

May 12, 2015

Chaperones are molecular helpers that assist other proteins with folding. One such chaperone is the so-called heat shock protein 60 (Hsp60). This protein forms structures in mitochondria that resemble barrels ...

Recommended for you

Hubble observes one-of-a-kind star nicknamed 'Nasty'

May 21, 2015

Astronomers using NASA's Hubble Space Telescope have uncovered surprising new clues about a hefty, rapidly aging star whose behavior has never been seen before in our Milky Way galaxy. In fact, the star is ...

Galaxy's snacking habits revealed

May 20, 2015

A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.

Supernova ignition surprises scientists

May 20, 2015

Scientists have captured the early death throes of supernovae for the first time and found that the universe's benchmark explosions are much more varied than expected.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.