New ring discovered around Saturn is largest in Solar System
A huge ring of dust has been discovered around Saturn that is about 50 times farther out into space than the planet’s known rings.
The faint hoop, the largest-known planetary ring in the Solar System, is believed to be made up of debris from one of Saturn’s moons, Phoebe.
According to the study, published tomorrow in the journal Nature, this dust is disturbed by minor impacts on Phoebe and drifts towards the planet where it is picked up by another of Saturn’s moons, Iapetus.
The dusty hoop extends about 8 million miles (13 million km) from the planet, and would be twice the size of the full Moon if it were visible from the Earth, Previously, the largest-known planetary rings were Jupiter’s gossamer rings and Saturn’s E ring — broad sheets of dust that extend to about 0five to ten times the radius of their planets.
The new ring is extremely faint, made up of a thin array of ice and dust particles. In a cubic kilometre of space there are only about 20 particles. “It’s very very tenuous. If you were standing in the ring itself, you wouldn't even know it,” said Dr Anne Verbiscer, an astronomer at the University of Virginia.
The ring was discovered using Nasa’s Spitzer Space Telescope to scan for infrared signals near Phoebe’s orbit. The telescope, which is currently 66 million miles (107 million km) from Earth in orbit around the Sun, picked up a faint glow of the ring’s cool dust particles.
The enormous ring may solve a longstanding riddle in astronomy: the two-tone colouration of Iapetus, which was first spotted by the astronomer Giovanni Cassini in 1671. The leading hemisphere of the moon is significantly darker than its trailing hemisphere.
Dr Verbiscer and colleagues calculate that, over the history of the Solar System, material from the ring could have supplied Iapetus’s front face with a blanket of dark dust. “It’s basically been sandblasted by small particles from the ring,” she said.
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