Posted on Mon, Oct. 12, 2009
It's hard to imagine astronomers going for so many years missing Saturn's largest ring. The previously unknown structure, announced last week, is 10 times bigger than the visible rings. It makes Saturn's signature symbol look like mini rubber bands inside a truck tire.
But this monster space doughnut is more or less invisible in ordinary light, said co-discoverer Anne Verbiscer of the University of Virginia. It took the infrared cameras aboard NASA's orbiting Spitzer telescope to finally capture it.
The new ring is made of dust and extends from 3.7 million miles to 7.4 million miles from Saturn's surface, with a vertical height that's 20 times the diameter of the planet.
"It's hard even for me to take this in," said Verbiscer. "It's a humbling thing."
She said her request to point NASA's Spitzer Telescope at Saturn might have been based on an error. She had been observing Saturn from the ground and thought she saw some signs that its distant moon Phoebe had brightened and dimmed. She hypothesized that she might be seeing dust and ice kicked up by a collision with a tiny meteorite - a sign that there was more debris circling around in Phoebe's orbit.
The Spitzer observations then revealed the previously unknown ring. Looking back into her earlier data, however, Verbiscer said she couldn't find the original brightening of Phoebe that led her to seek out the ring, and now wonders if it was ever really there.
"It's a kind of funny situation," she said, "of a possible mistake turning out to have a huge scientific payoff." - Faye Flam
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