Something is disturbing the famed, majestic rings of Saturn as well as the lesser-known rings around Jupiter. The ring systems, which appear at first glance to be planar, wafer-thin bands of ice and dust, have on closer examination been found to be rippled, like a corrugated tin roof.

The culprit in both cases appears to be cometary debris strikes that tilted the rings, a tilt that over the years became twisted up into a spiral pattern of ripples within the rings. That is the conclusion of two studies published online March 31 in Science—one study on Saturn, one about Jupiter—which go on to pinpoint specific dates that debris plowed into the rings to generate ripples: late 1983 for Saturn; mid-1994 for Jupiter.

It is a forensic story that spans decades, as well as billions of kilometers of interplanetary space, and for which four spacecraft were called into service. NASA's Galileo spacecraft, orbiting Jupiter at the time, first noticed what turned out to be corrugations in the planet's main ring in 1996, but the nature of the ring features was somewhat unclear at the time. "Pretty much it was just one of those things where you stare at it and say, 'Huh, I hope we get more data,'" says Mark Showalter, a planetary astronomer at the SETI Institute in Mountain View, Calif., and the lead author of the study on Jupiter's rings.

It was not until 13 years later, when NASA's Cassini spacecraft noticed something similar as it orbited Saturn, that the pieces of the puzzle began to fit together. Cassini was exploring the Saturnian system during the planet's 2009 equinox, when the ring plane aligns with the center of the sun. With the sun at such a low angle, vertical corrugations within the rings cast long shadows that Cassini was able to identify. Some were just two meters high, about as tall as Los Angeles Lakers guard Kobe Bryant. They looked like a system of nearly concentric ripples, as would be formed if the rings had somehow been knocked out of alignment and then twisted into a tight, corrugated spiral by Saturn's gravity.

"This corrugation seemed to have formed at some discrete time in the past—1983," says Matt Hedman, a planetary scientist at Cornell University who led the Saturn study. "Something caused the rings to tilt, and we were seeing that tilted pattern wound up." But just what happened in 1983 remained unknown; one early hypothesis held that Saturn itself lurched somehow, throwing the planet and rings out of alignment.

The discovery of rippled rings at Saturn led to a reevaluation of the Jovian data, including a look at some later Galileo imagery from 2000 and images taken by the New Horizons probe in 2007 as it swung past Jupiter en route to Pluto. Showalter also dug up archival Hubble data of Jupiter, but its viewing angles did not allow for a good look at the ring structure. "One of the eureka moments was when we realized that if it was the same thing we were seeing at Saturn, it wouldn't look the same" as it did in 1996, Showalter says. "If that's the same physics that we see at Saturn, then we've been looking for the wrong pattern." As the tilt becomes more and more twisted into the ring, the spiral pattern gets tighter and the spacing between ripples shrinks; the corrugations that were almost 2,000 kilometers apart in 1996 were only 700 kilometers apart by 2000. In 2007, when New Horizons flew by, the spacing between corrugations was a mere 350 kilometers.

Tracing the evolution of the ripples backward in time, Showalter and his colleagues found that the ring had been tilted by about two kilometers at some time between July and October 1994. That was a huge clue pointing to a potential culprit in the interplanetary mystery—Comet Shoemaker-Levy 9 hit Jupiter in July 1994, bombarding the planet in a large, well-documented impact. Debris from the comet, which had broken up before it hit Jupiter in a number of fragments over the course of several days, seems have knocked Jupiter's rings out of whack. "That was basically our smoking gun," Showalter says.

That finding, in turn, shed light on what may have happened at Saturn. "Then we went, 'Oh, maybe this is the same sort of thing,'" Hedman says. "To tilt a broad region of the ring you need something kind of like an intense meteor shower," he says. A single, intact asteroid or comet would punch right through the ring, but a good-size comet, if broken apart as Shoemaker-Levy 9 was, could rain down on the rings with enough force to generate a sufficient tilt. (Saturn was sunward from Earth around the time of the presumed 1983 impact, so astronomers on Earth would not have been able to see it.)

The similarity between the ripple phenomena at the two planets—and the temporal connection between Shoemaker-Levy 9 and Jupiter's ripples—lends the research credibility with other ring scientists. "The fact that the biggest thing that we saw with our eyes agrees with the biggest influence in the rings of Jupiter is pretty compelling," says Jeff Cuzzi, a planetary scientist and Cassini team member at NASA Ames Research Center, Moffett Field, Calif., who did not contribute to the new studies.

"I think it's a very compelling argument, especially with the two papers together," says Linda Spilker, a planetary scientist and Cassini project scientist at the NASA Jet Propulsion Laboratory in Pasadena, Calif., who also did not contribute to the new studies. "I know we've been puzzling away on the Saturn side and looking at various explanations—linking to an event in the Jovian system really helps."

Spilker notes that Cassini has another several years of planned operation at Saturn; the spacecraft could document such a ring disruption if such debris strikes occur often enough. "Maybe if we can get lucky, we can be there and actually witness an event like this," she says.

For the time being, the puzzle seems to work as assembled. "We're taking pieces that nobody would have thought fit together," Showalter says. "And we're finding one fairly simple story—it's comets hitting the rings and tilting them, and the tilts turn into spirals. It's a fun thing to piece together."

4 Comments

1. 1. edromar 10:21 PM 3/31/11

   jOHN mATSON: Well, at least people are coming to recognize how commonly coments hit and/or explode approaching impact to cause disruptions on heavenly bodies such as the explosion of a comet over the North Pole 10.5 K years ago caused earthquakes leading to massive tsunami floods out of the Arctic Ocean South over the whole Northern hemisphere, creating an order of havoc far beyond Tunguski where the Comet exploded over a relatively stable area without massiv e waters to flow in tsunamis!

   Reply | Report Abuse | Link to this

2. 2. scottryan1 07:00 AM 4/4/11

   BLACK HOLES & MATTER & ANTI MATTER UNIVERSE
   
   
   Matter & anti matter. It starts a new line or there is matter universe on top & anti matter universe on the bottom.
   This is why black holes are formed.
   So once a star blast in that fast & with force, you punch a hole into the other side, that is anti matter universe.
   
   There is a anti matter world below us or a parallel universe, & the lines are breached that forms a black hole. So when everyone says there is know anti matter they are wrong & that is why.
   
   Under us or in a parallel universe there is a universe of anti matter, & it’s a star that collapses that will connect the 2 worlds because of the force made. As in 356 quintillion gauss compressed into a pin point in a split second makes the force & or mass matter & anti matter form. or opens the door way by punching a hole joining the 2 universe together.
   it will brake & punch a hole into this world, so a black hole is in away, a different universe. it’s a anti matter universe.
   .
   Ether way I believe that a black hole connects us to a anti matter universe.
   This is why a black hole go nuts & sucks in everything.
   
   so does that mean that any matter getting sucked into a black hole would blow up in the other anti matter universe instantly. the force is visible but it is invisible when anti matter & matter meet. the energy is massive.
   so we just see the energy force / a black hole when they meet. let alone when lots of matter gets sucked in.
   
   Its almost like water & a drain & pulling the plug. gravity will make it go down. so it swells with massive gravity inside the black hole, because the 2 different universes are up & below. the matter & antimatter will meet & explode that makes massive force / energy in a black hole, but invisible force to the eyes of us. that is the same as a black hole, they are invisible and only its energy can be seen. so that means it is matter & anti matter that meet in a black hole or once it gets in, in it.
   

   Reply | Report Abuse | Link to this

3. 3. scottryan1 07:04 AM 4/4/11

   time may also go backwards in a black hole. well as you go down. so it will take you back to a time where there was anti matter everywhere.
   
   its almost like 1 massive black hole will form & time will go back to the beginning & all matter will meet & explode.
   
   the 2 matters must meet. it must make a black hole on both sides from the punching force. well it meets at the same point. so the second it gets to the centre or so on, it will blast out on both sides.
   
   so in the centre of a black hole there is no force or gravity. even gravity has been pushed off to the sides. this way radiation gets spit out. matter & anti matter must make microwave radiation or.
   
   the big bang, matter and anti matter hit each other, & there was microwave radiation everywhere, or it makes dark matter blow up or increase its energy, there for shooting radiation out with force .
   
   for that to be so, nothing must get sucked into a black hole from the center, it must all get sucked in from the sides.
   
   that and or dark matter explodes from the force matter & anti matter hitting each other makes. there for like the microwave bubble, it makes microwave radiation like the bubble around the universe after the BIG BANG. so when dark matter gets sucked in it, it will explode under the force of antimatter & matter makes. well somthing like that.
   
   the 2 matters must meet. it must make a black hole on both sides from the punching force. well it meets at the same point. so the second it gets to the centre or so on, it will blast out on both sides.
   maybe its like 2 black holes back to front even, or just 1 from that blast of the star puching a hole in space time wrape into the anti matter universes..
   
   well maybe when the matter & anti matter meet, they form radiation. the back ground here is a microwave radiation background in this universe. is that the type it spits out of the black hole as well.
   
   Or you could also say cold & dark matter that blow up when it hits matter & anti matter makes the radiation. for the big bag to happen, dark matter must hit matter & anti matter, or but blow up under that force, maybe.
   
   Not only that the force must be massive, if matter & anti matter formed in this universe it must have made a massive amount microwave radiation. so why is that everywhere. when they meet it must make / spit out massive amounts or microwave radiation.
   
   

   Reply | Report Abuse | Link to this

4. 4. scottryan1 07:05 AM 4/4/11

   well that will at least explain how stuff can come shooting out. no gravity or force in the centre or top of the black hole. gravity has its self been pushed off to the sides, some how stooping force from being in the centre.
   
   it also explains a bit of the sting theory.

   Reply | Report Abuse | Link to this