Yet Another Ring for Saturn

On Tuesday, October 6, NASA announced the discovery by the Spitzer Space Telescope of yet another ring around the planet Saturn, and the size of this one is tremendous.

The newly discovered ring has an orbital tilt of 27 degrees from Saturn’s main ring plane. Most of the ring’s material starts about six million kilometers—3.7 million miles—away from Saturn and extends outward for roughly another 12 million kilometers—7.4 million miles. Phoebe, one of Saturn’s most distant moons, actually orbits within the ring, and is suspected to be the source of the ring material.

This new ring is not as flat as the others. Its vertical height is about 20 times the diameter of Saturn—meaning that it would take about one billion tightly-packed Earth’s to fill the space of the new ring. The ring is made of ice and dust particles, but it is very, very, very fine stuff. Some have compared their size to smoke particles. Also, the particles are spread out pretty well—if you were floating in the ring you could not detect any haze created by the particles. This ring would be extremely difficult to spot in visible light, but Spizter’s infrared instruments were able to spot the cooler band of material—about 80 Kelvin, or minus 316 degrees Fahrenheit—in the slightly “warmer” space surrounding it.

Artist’s conception of the newly found ring. Image Credit: NASA

Scientists think the discovery may help to answer the question of why Saturn’s moon Iapetus has a strange appearance. Discovered by Giovanni Cassini in 1671, Iapetus has one side that is bright while the other side is very dark. The pattern of light and dark shading has been compared to the yin-yang symbol. The dark side was name Cassini Regio in honor of the astronomer.

Image of Saturn’s moon Iapetus taken September 2007 by NASA’s Cassini spacecraft. Image Credit: NASA

Some scientists suggest that the particles in the newly found ring may be responsible for the two-toned affect on Iapetus. The new ring circles in the same direction as Phoebe, while Iapetus, the other rings and most of Saturn’s moons are circling in the opposite direction. Some suggest that the material from the ring drifts inward, toward Iapetus, and builds up over time to create the darker Cassini Regio portion. Many have wondered if Phoebe had something to do with the coloration on Iapetus, and this would seem to be the proof astronomers had been looking for.

NASA’s Spitzer Space Telescope—the largest infrared telescope—was launched August 25, 2003 and is currently 107 million kilometers (66 million miles) from Earth in orbit around the sun. The discovery of the new ring came before May of this year, when Spitzer ran out of the onboard coolant necessary to keep its infrared-observing instruments at an optimal temperature. Spitzer has now begun a “warmer” mission, making the best observations that it can in less-than-optimum circumstances. To learn more about this discovery and about the Spitzer mission, check out these links:

Artist’s conception of the newly found ring
http://www.nasa.gov/mission_pages/spitzer/multimedia/spitzer-20091007a.html

Image of Saturn’s moon Iapetus taken September 2007 by NASA’s Cassini spacecraft
http://photojournal.jpl.nasa.gov/catalog/PIA08384

NASA's Spitzer Space Telescope Mission Home Page
http://www.spitzer.caltech.edu/

-