NASA’s Cassini spacecraft has provided the first direct evidence of small meteoroids breaking into streams of rubble and crashing into Saturn’s rings.
These observations make Saturn’s rings the only location besides Earth, the Moon and Jupiter where meteor impacts have been observed as they occur. The meteoroids at Saturn are estimated to range from about one-half inch to several yards (1 centimeter to several meters) in size.
“These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth — two very different neighborhoods in our solar system — and this is exciting to see,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “It took Saturn’s rings acting like a giant meteoroid detector — 100 times the surface area of the Earth — and Cassini’s long-term tour of the Saturn system to address this question.”
A rain of ionized water molecules falls into Saturn’s upper atmosphere from its rings, researchers from England’s University of Leicester have found. Using images from NASA’s Voyager spacecraft and more recent near-infrared observations from the Keck Observatory in Hawaii, it has been found that dark bands seen across Saturn are actually the “rain shadows” of particles from the rings interacting with the planet’s atmosphere, effectively cooling it and reducing heat emissions in those areas.
“Saturn is the first planet to show significant interaction between its atmosphere and ring system,” said James O’Donoghue, the paper’s lead author and a postgraduate researcher at Leicester. “The main effect of ring rain is that it acts to ‘quench’ the ionosphere of Saturn. In other words, this rain severely reduces the electron densities in regions in which it falls.”
Saturn’s F ring is a fascinating structure. Made of fine icy particles — most no larger than the particulates found in cigarette smoke — it orbits Saturn just outside the A ring and is easily perturbed by the gravity of nearby moons and embedded moonlets, which create streamers and clumps that rise up in fanciful shapes.
This brief animation, made from 33 raw images captured by Cassini on December 26 (otherwise known locally as my birthday!) shows the F ring in action as it follows shepherd moons Prometheus and smaller Atlas around Saturn. Some motion is due to the orbits of the rings and moons, and some is due to the spacecraft itself.
You can watch a slower version of the animation below:
Captured on Christmas Day, this is a raw image from Cassini showing Saturn’s F ring buckling inwards at two places due to the gravitational tug of its inner shepherd moon, Prometheus, seen at center.
As the irregularly-shaped moon approaches the ring material in its looping orbit around Saturn it draws material from the ring in towards itself, warping and stretching the fine icy ring particles into waving streamers that eventually settle back into place. It’s a very visual demonstration of gravity at work!
At its widest Prometheus is about 92 miles (148 km) across but only 42 miles (68 km) in width. It orbits Saturn once every 14.7 hours.
Raw image: NASA/JPL/Space Science Institute
As a sort of Christmas gift to the world, the Cassini mission team released this image today, a majestic mosaic showing the planet Saturn gleaming in backlit sunlight.
“Of all the many glorious images we on Cassini have received from Saturn, none are more strikingly unusual than those we have taken from within Saturn’s shadow,” said Cassini imaging team director Carolyn Porco. “They unveil a rare splendor seldom seen anywhere else in our solar system.”
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Go ahead, take a look. Let it sink in…..waaaait for it…… there. I told you.
Still wondering what it is you’re looking at? That’s ok, you’ll love it even after I tell you.
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