Saturn is the smaller of the two gas-giant planets dwelling in the outer regions of our Solar System, far from the friendly light and warmth of our incandescent golden Star, the Sun. The larger of the two gas-giants is Jupiter, which is also the largest planet in our Solar System. Some scientists think that the two gas giants do not have solid surfaces hidden beneath their immense and heavy gaseous envelopes, although others think that they probably do contain relatively small cores of rocky-icy material. The two other large denizens of the outer limits of our Sun's family are Uranus and Neptune, which are classified as ice-giants, because they have large icy cores buried beneath their heavy atmospheres which, though massive, are not nearly as heavy as the gaseous atmospheres borne by the two gas-giants.
Saturn is probably the most beautiful planet in our Sun's lovely family, with its magnificent system of enchanting rings, gleaming icy moons, and myriads of tumbling moonlets that dance and somersault both within and outside of the rings. One of Saturn's moons is Titan, the second largest moon in our Solar System, after Ganymede of Jupiter. Shrouded in a dense orange mist, Titan is famous for its frozen clouds of methane, and hydrocarbon seas and lakes. Titan's thick, veiling atmosphere is composed of a wonderful icy soup of compounds very much like those thought to have been present in Earth's primordial atmosphere. Titan's thick atmosphere--which is much denser than Earth's atmosphere--contains mostly nitrogen, like that of our own planet. But Titan's atmosphere also contains significantly greater percentages of such so-called "smoggy" chemicals as methane and ethane. The smog on Titan is so extremely dense that it actually rains "gasoline-like" liquids down on the surface of this bizarre world. Indeed, some of the chemicals discovered in Titan's atmosphere might indicate that simple and primitive methane-based life (methanogens), might dwell on this truly weird moon.
Until 2004, no spacecraft had visited Saturn in over two decades. Pioneer 11 had snapped the very first close-up images of Saturn when it flew past in 1979, Voyager 1 had its rendezvous about a year later, and in August 1981 Voyager 2 had its brief but highly productive encounter. At last, on July 1, 2004, NASA's Cassini spacecraft went into orbit around Saturn, and started taking breathtaking photographs.
Saturn has 62 known moons. Most of them are very small, icy worldlets. On June 11, 2004, shortly before arriving at Saturn, the Cassini spacecraft made its only flyby--at an altitude of 2,000 kilometers--past the very tiny icy moon Phoebe. Phoebe is a heavily cratered worldlet that circles its planet backwards--indicating that it is a captured object, born elsewhere, and not an original member of Saturn's family.
Most of Saturn's natural satellites are very small and icy dancing moonlets. However, the larger, icy midsized moons twirl around their enormous ringed planet in a lovely and mysterious dance. The largest of the icy moons is Rhea, Saturn's second-largest moon after the weird world that is Titan. Iapetus, the third largest of Saturn's moons, is two-faced, with one side composed of gleaming, very bright, highly reflective ice, and the other, dark and non-reflective, a blackened splotch staining the pristine white ice. Iapetus is larger than Mimas and Enceladus. There is an enormous impact crater on the moon Mimas, that stands out as a prominent feature on what is apparently a badly bombarded, heavily cratered world. The large impact crater Herschel on this 400-kilometer moon was excavated by a tumbling chunk of space-stuff made of rock, ice, or both, that came very close to powdering the entire little moon. Another icy moon, Enceladus, is a bewitching world, 500-kilometers in diameter, that is thought to harbor a global subsurface ocean beneath its frozen crust. Where there is liquid water there is always the possibility--though, by no means, the promise--of life. Enceladus also has the highest albedo of any other moon in our Solar System. This means that it has the most dazzlingly bright reflective surface. It also possesses a very active geology, rendering it almost free of craters because it is constantly being resurfaced by the emissions of gushing icy geysers that are responsible for fresh snow that keeps the surface of the little moon sparkling and smooth.
Research presented on October 19, 2012, at the annual meeting of the American Astronomical Society's Division for Planetary Sciences held in Reno, Nevada, has suggested a causal relationship between the seven sister moons--Titan and the six mid-sized icy moons of Saturn. The researchers suggest that the seven moons have a violent origin, and came into being when a few considerably larger moons crashed into each other to give birth to the misty, moisty moon, Titan.
According to this theory, the Saturn system began with a family of several relatively large moons, analogous to the four large Galilean moons of Jupiter--Io, Europa, Ganymede, and Callisto. However, strange and violent things happened in the Saturn system that drove its large moons onto a collision course with destiny. According to the theory, there were a few dramatic moon mergers, forming the Titan that we now know--but there was also a sufficiently large quantity of moon-stuff left over from the collisions to create the icy mid-sized satellites--Mimas, Iapetus, Enceladus, Tethys, Dione, and Rhea!
"We think that the giant planets got their satellites kind of like the Sun got its planets, growing like miniature solar systems and ending with a stage of final collisions," lead author Dr. Erik Asphaug, of the University of California at Santa Cruz, said in a statement to the press on October 18, 2012.
He added that "In our model for the Saturn system, we propose that Titan grew in a couple of giant impacts, each one combining the masses of the colliding bodies, while shedding a small family of middle-sized moons."
Such moon-forming mergers and collisions are not unheard of. For example, the leading theory explaining the formation of Earth's own large Moon, suggests that it was born about 4.5 billion years ago when a Mars-sized protoplanet, dubbed Theia by astronomers, collided with our planet. Just as our Moon is identical geologically to Earth's mantle, the six medium-sized icy sister moons of Saturn are all similar in composition to Titan's icy mantle, the researchers announced in October 2012.
"Our model explains the diversity of these ice-rich moons and the evidence for their very active geology and dynamics. It also explains a puzzling fact about Titan, in that a giant impact would give it a high orbital eccentricity," Asphaug continued to explain to the press on October 18, 2012.
Jupiter, like Saturn, is circled by more than 60 known satellites. Many of them are tiny moonlets, measuring only a few miles across, and are probably captured asteroids or minor planets--or their shattered remains.
Asphaug and co-author Dr. Andreas Reufer of the University of Bern in Switzerland, devised their new giant impact model using sophisticated computer simulations. They discovered that mergers between moons the size of Jupiter's Galilean satellites--which range in size from 1,940 miles wide (Europa) to 3, 271 miles across (Ganymede)--would tear icy stuff off the outer layers of the colliding moons. This icy material would then form spiral arms, which would ultimately merge together due to gravitational attraction to create Saturn's mid-sized icy moons.
The moon-mergers may have happened very long ago--or maybe quite recently. The mergers could have been tripped off by gravitational disruption caused by a migrating giant planet such as Uranus or Neptune, the researchers told the press in October 2012.
"What makes the Saturn system so beautiful and unique could be its youth. While we don't have a preferred time frame for this origin scenario to play out, it could have happened recently if something came along to destabilize the Saturn system, triggering the collisional mergers that formed Titan," Asphaug added.
Saturn is probably the most beautiful planet in our Sun's lovely family, with its magnificent system of enchanting rings, gleaming icy moons, and myriads of tumbling moonlets that dance and somersault both within and outside of the rings. One of Saturn's moons is Titan, the second largest moon in our Solar System, after Ganymede of Jupiter. Shrouded in a dense orange mist, Titan is famous for its frozen clouds of methane, and hydrocarbon seas and lakes. Titan's thick, veiling atmosphere is composed of a wonderful icy soup of compounds very much like those thought to have been present in Earth's primordial atmosphere. Titan's thick atmosphere--which is much denser than Earth's atmosphere--contains mostly nitrogen, like that of our own planet. But Titan's atmosphere also contains significantly greater percentages of such so-called "smoggy" chemicals as methane and ethane. The smog on Titan is so extremely dense that it actually rains "gasoline-like" liquids down on the surface of this bizarre world. Indeed, some of the chemicals discovered in Titan's atmosphere might indicate that simple and primitive methane-based life (methanogens), might dwell on this truly weird moon.
Until 2004, no spacecraft had visited Saturn in over two decades. Pioneer 11 had snapped the very first close-up images of Saturn when it flew past in 1979, Voyager 1 had its rendezvous about a year later, and in August 1981 Voyager 2 had its brief but highly productive encounter. At last, on July 1, 2004, NASA's Cassini spacecraft went into orbit around Saturn, and started taking breathtaking photographs.
Saturn has 62 known moons. Most of them are very small, icy worldlets. On June 11, 2004, shortly before arriving at Saturn, the Cassini spacecraft made its only flyby--at an altitude of 2,000 kilometers--past the very tiny icy moon Phoebe. Phoebe is a heavily cratered worldlet that circles its planet backwards--indicating that it is a captured object, born elsewhere, and not an original member of Saturn's family.
Most of Saturn's natural satellites are very small and icy dancing moonlets. However, the larger, icy midsized moons twirl around their enormous ringed planet in a lovely and mysterious dance. The largest of the icy moons is Rhea, Saturn's second-largest moon after the weird world that is Titan. Iapetus, the third largest of Saturn's moons, is two-faced, with one side composed of gleaming, very bright, highly reflective ice, and the other, dark and non-reflective, a blackened splotch staining the pristine white ice. Iapetus is larger than Mimas and Enceladus. There is an enormous impact crater on the moon Mimas, that stands out as a prominent feature on what is apparently a badly bombarded, heavily cratered world. The large impact crater Herschel on this 400-kilometer moon was excavated by a tumbling chunk of space-stuff made of rock, ice, or both, that came very close to powdering the entire little moon. Another icy moon, Enceladus, is a bewitching world, 500-kilometers in diameter, that is thought to harbor a global subsurface ocean beneath its frozen crust. Where there is liquid water there is always the possibility--though, by no means, the promise--of life. Enceladus also has the highest albedo of any other moon in our Solar System. This means that it has the most dazzlingly bright reflective surface. It also possesses a very active geology, rendering it almost free of craters because it is constantly being resurfaced by the emissions of gushing icy geysers that are responsible for fresh snow that keeps the surface of the little moon sparkling and smooth.
Research presented on October 19, 2012, at the annual meeting of the American Astronomical Society's Division for Planetary Sciences held in Reno, Nevada, has suggested a causal relationship between the seven sister moons--Titan and the six mid-sized icy moons of Saturn. The researchers suggest that the seven moons have a violent origin, and came into being when a few considerably larger moons crashed into each other to give birth to the misty, moisty moon, Titan.
According to this theory, the Saturn system began with a family of several relatively large moons, analogous to the four large Galilean moons of Jupiter--Io, Europa, Ganymede, and Callisto. However, strange and violent things happened in the Saturn system that drove its large moons onto a collision course with destiny. According to the theory, there were a few dramatic moon mergers, forming the Titan that we now know--but there was also a sufficiently large quantity of moon-stuff left over from the collisions to create the icy mid-sized satellites--Mimas, Iapetus, Enceladus, Tethys, Dione, and Rhea!
"We think that the giant planets got their satellites kind of like the Sun got its planets, growing like miniature solar systems and ending with a stage of final collisions," lead author Dr. Erik Asphaug, of the University of California at Santa Cruz, said in a statement to the press on October 18, 2012.
He added that "In our model for the Saturn system, we propose that Titan grew in a couple of giant impacts, each one combining the masses of the colliding bodies, while shedding a small family of middle-sized moons."
Such moon-forming mergers and collisions are not unheard of. For example, the leading theory explaining the formation of Earth's own large Moon, suggests that it was born about 4.5 billion years ago when a Mars-sized protoplanet, dubbed Theia by astronomers, collided with our planet. Just as our Moon is identical geologically to Earth's mantle, the six medium-sized icy sister moons of Saturn are all similar in composition to Titan's icy mantle, the researchers announced in October 2012.
"Our model explains the diversity of these ice-rich moons and the evidence for their very active geology and dynamics. It also explains a puzzling fact about Titan, in that a giant impact would give it a high orbital eccentricity," Asphaug continued to explain to the press on October 18, 2012.
Jupiter, like Saturn, is circled by more than 60 known satellites. Many of them are tiny moonlets, measuring only a few miles across, and are probably captured asteroids or minor planets--or their shattered remains.
Asphaug and co-author Dr. Andreas Reufer of the University of Bern in Switzerland, devised their new giant impact model using sophisticated computer simulations. They discovered that mergers between moons the size of Jupiter's Galilean satellites--which range in size from 1,940 miles wide (Europa) to 3, 271 miles across (Ganymede)--would tear icy stuff off the outer layers of the colliding moons. This icy material would then form spiral arms, which would ultimately merge together due to gravitational attraction to create Saturn's mid-sized icy moons.
The moon-mergers may have happened very long ago--or maybe quite recently. The mergers could have been tripped off by gravitational disruption caused by a migrating giant planet such as Uranus or Neptune, the researchers told the press in October 2012.
"What makes the Saturn system so beautiful and unique could be its youth. While we don't have a preferred time frame for this origin scenario to play out, it could have happened recently if something came along to destabilize the Saturn system, triggering the collisional mergers that formed Titan," Asphaug added.
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