Lumps in the Rings of Saturn

"Surprising, Huge Peaks Discovered in Saturn's Rings "
Space.com (September 21, 2009)

"Stunning new views of Saturn from a NASA spacecraft have revealed odd formations in the planet's trademark rings, including ripples as tall as the Rocky Mountains.

"The new images taken by NASA's Cassini spacecraft show that Saturn's icy rings - once thought to be relatively thin - can be miles thick in some points and include weird, bright streaks from clouds kicked up by the cosmic clash between ring particles and interloping space debris.

" 'It's like putting on 3-D glasses and seeing the third dimension for the first time,' said Bob Pappalardo, Cassini's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., in a statement. 'This is among the most important events Cassini has shown us.'

"Cassini recorded the new images of Saturn in the week surrounding the planet's Aug. 11 equinox, a time when its bright bands of rings are edge on to the sun and nearly invisible as seen from Earth...."

This is a pretty big deal.

"...'We thought the plane of the rings was no taller than two stories of a modern-day building and instead we've come across walls more than 2 miles [3 kilometers] high,' said Cassini imaging team leader Carolyn Porco at the Space Science Institute in Boulder, Colo....

"One ripple rises nearly 2 1/2 miles (4 km) above the plane of Saturn's rings. The big blip is caused by the gravitational tug of the planet's moon Daphnis. It is the highest peak among the rings, mission managers said...."

These miles-high ripples in the rings apparently are easier to detect when the rings are edge-on to the sun: something that hasn't happened since the last Saturnian equinox, about fifteen years ago. This time, we've got a robot out there: orbiting Saturn. Cassini has been there since October of 1997. (Moon and Planets Exploration Timeline, Space Today Online)

Previous Saturn missions were flybys, where spacecraft whip past planets, gathering as much information as possible. Missions like that are valuable, revealing new details, but sort of like a whirlwind tour of Europe: When it's over, you've got a lot of pictures, a lot of information, some general impressions - but not the sort of knowledge that comes from sticking around for a while.

The Space.com article has four photos - three of the new features.