By: Staff, SPACE.com
Published: 03/29/2013 12:22 PM EDT on SPACE.com
The dazzling rings of Saturn and its moons are likely more than 4 billion years old — the cosmic remnants of the solar system's birth, scientists say.
The finding comes after a new study of observations from NASA's Cassini spacecraft orbiting Saturn, which suggests that the planet's rings and moons formed at the same time as the rest of the solar system's planetary bodies soon after the sun sparked into life. Since Saturn's rings and moons formed from the same planetary nebula of gas and dust around the early sun that led to the solar system's other planets, they are a time capsule of sorts for astronomers, the researchers said.
These two global images of Iapetus show the extreme brightness dichotomy on the surface of this peculiar Saturnian moon. The left-hand panel shows the moon's leading hemisphere and the right-hand panel shows the moon's trailing side.
"Studying the Saturnian system helps us understand the chemical and physical evolution of our entire solar system," Cassini scientist Gianrico Filacchione, of Italy's National Institute for Astrophysics in Rome, said in a statement. "We know now that understanding this evolution requires not just studying a single moon or ring, but piecing together the relationships intertwining these bodies."
Filacchione and his colleagues analyzed data from Cassini's visual and infrared mapping spectrometer, or VIMS, to understand the distribution of water ice and colors across Saturn's rings and moons. Different colors in the rings and moons provide evidence of non-water organic materials, while water ice is a vital clue into the timeline that led to the formation of the Saturnian system, the researchers said. [See photos of Saturn's spectacular rings up close]
Observations from VIMS showed that there is too much water ice in the Saturn system to have been dumped there by comets or other more recent means, leading the researchers to conclude that the water ice must have formed around the time the solar system did.
The researchers also discovered that the surfaces of Saturn's moons typically get redder the farther away they orbit the huge planet. Some of these outer moons, like Hyperion and Iapetus, may have been coated with reddish dust shed by Phoebe, a small, retrograde moon believed to have originated in the Kuiper Belt, the researchers said.
Meanwhile, parts of the planet's main ring system may have been painted with a more subtle reddish hue by meteoroids slamming into the Saturnian system. That red may be a sign of oxidized iron (rust) or polycyclic aromatic hydrocarbons, compounds that could give rise to more complex molecules, the researchers said.
The scientists were surprised to observe reddish tones on the potato-shaped moon Prometheus, which orbits in an area where moons are generally more whitish in color. The finding hints that Saturn's rings may have given rise to some of the planet's moons.
"Scientists had been wondering whether ring particles could have stuck together to form moons — since the dominant theory was that the rings basically came from satellites being broken up," study researcher Bonnie Buratti, a VIMS team member based at NASA's Jet Propulsion Laboratory, Pasadena, Calif., said in a statement. "The coloring gives us some solid proof that it can work the other way around, too."
The research is detailed in the March 26 edition of the Astrophysical Journal.
NASA's Cassini spacecraft launched toward Saturn in 1997 and arrived in orbit around the ringed planet in 2004. The spacecraft completed its primary mission in 2008 and is currently in the midst of its second extended mission, which runs through 2017.
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A crescent Enceladus appears with Saturn's rings in this Cassini spacecraft view of the moon.
With giant Saturn hanging in the blackness and sheltering Cassini from the sun's blinding glare, the spacecraft viewed the rings as never before, revealing previously unknown faint rings and even glimpsing its home world.
This is an artist's concept of the Saturnian plasma sheet based on data from Cassini magnetospheric imaging instrument. It shows Saturn's embedded 'ring current,' an invisible ring of energetic ions trapped in the planet's magnetic field. Saturn is at the center, with the red 'donut' representing the distribution of dense neutral gas outside Saturn's icy rings. Beyond this region, energetic ions populate the plasma sheet to the dayside magnetopause filling the faintly sketched magnetic flux tubes to higher latitudes and contributing to the ring current. The plasma sheet thins gradually toward the nightside. Image Credit: NASA/JPL/JHUAPL
A quartet of Saturn's moons, from tiny to huge, surround and are embedded within the planet's rings in this Cassini composition.
This stunning false-color view of Saturn's moon Hyperion reveals crisp details across the strange, tumbling moon's surface. Differences in color could represent differences in the composition of surface materials. The view was obtained during Cassini's very close flyby on Sept. 26, 2005. Hyperion has a notably reddish tint when viewed in natural color. The red color was toned down in this false-color view, and the other hues were enhanced, in order to make more subtle color variations across Hyperion's surface more apparent.
The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft.
Vertical structures, among the tallest seen in Saturn's main rings, rise abruptly from the edge of Saturn's B ring to cast long shadows on the ring in this image taken by NASA's Cassini spacecraft two weeks before the planet's August 2009 equinox. Part of the Cassini Division, between the B and the A rings, appears at the top of the image, showing ringlets in the inner division.
Flying past Saturn's moon Dione, Cassini captured this view which includes two smaller moons, Epimetheus and Prometheus, near the planet's rings.
Data from NASA's Cassini spacecraft show that the sizes and patterns of dunes on Saturn's moon Titan vary as a function of altitude and latitude. Image credit: NASA/JPL-Caltech, and NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team
Saturn's small, potato-shaped moon Prometheus appears embedded within the planet's rings near the center of this Cassini spacecraft view while the larger moon Mimas orbits beyond the rings.
The line of Saturn's rings disrupts the Cassini spacecraft's view of the moons Tethys and Titan.
Although traveling at great speed, the Cassini spacecraft managed to capture this close view of Saturn's small moon Helene during a flyby on March 3, 2010. Saturn's atmosphere makes up the background of this composition.
The Cassini spacecraft looks at a brightly illuminated Enceladus and examines the surface of the leading hemisphere of this Saturnian moon.
Saturn's third-largest moon Dione can be seen through the haze of its largest moon, Titan, in this view of the two posing before the planet and its rings from NASA's Cassini spacecraft.
Saturn's moon Mimas peeks out from behind the night side of the larger moon Dione in this Cassini image captured during the spacecraft's Dec. 12, 2011, flyby of Dione.
A quintet of Saturn's moons come together in the Cassini spacecraft's field of view for this portrait.
The best view of Saturn's rings in the ultraviolet indicates there is more ice toward the outer part of the rings, than in the inner part, hinting at the origins of the rings and their evolution.
NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011.
Recent Cassini images of Saturn's moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. The image was taken looking more or less broadside at the 'tiger stripe' fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb of the moon. The greatly enhanced and colorized image shows the enormous extent of the fainter, larger-scale component of the plume.
NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011.
Saturn sits nested in its rings of ice as Cassini once again plunges toward the graceful giant. This natural color mosaic was acquired by the Cassini spacecraft as it soared 39 degrees above the unilluminated side of the rings.