Spitzer Discovers Largest Ring Around Saturn
NASA’s Spitzer Space Telescope has discovered an enormous ring around Saturn – by far the largest of the giant planet’s many rings.
The new belt lies at the far reaches of the Saturnian system, with an orbit tilted 27 degrees from the main ring plane. The bulk of its material starts about six million kilometers away from the planet and extends outward roughly another 12 million kilometers. One of Saturn’s farthest moons, Phoebe, circles within the newfound ring, and is likely the source of its material.
Saturn’s newest halo is thick, too – its vertical height is about 20 times the diameter of the planet. It would take about one billion Earths stacked together to fill the ring. The ring itself is tenuous, made up of a thin array of ice and dust particles. Spitzer’s infrared eyes were able to spot the glow of the band’s cool dust.
The ring would be difficult to see with visible-light telescopes. Its particles are diffuse and may even extend beyond the bulk of the ring material all the way in to Saturn and all the way out to interplanetary space. The relatively small numbers of particles in the ring wouldn’t reflect much visible light, especially out at Saturn where sunlight is weak.
Spitzer was able to sense the glow of the cool dust, which is only about 80 Kelvin (minus 316 degrees Fahrenheit). Cool objects shine with infrared, or thermal radiation; for example, even a cup of ice cream is blazing with infrared light. By focusing on the glow of the ring’s cool dust, Spitzer made it easy to find.