Tuesday, August 3, 2010

A Special Time for Saturn

Photo courtesy of NASA
This is a special time for those of us who have a fascination with Saturn. Shortly after sunset, look toward the west and you'll see three planets in a line. The brightest is Venus. Above it and to the left is Mars, distinctly reddish but much fainter. And just beyond that, Saturn. Check them out -- binoculars will work just fine (they're far better than Galileo's astronomical telescope). You might -- emphasis on "might" -- be able to see Saturn's rings. Or you might see the "Mickey Mouse ears" that Galileo saw and described in his sketchbook. 

Unfortunately, his telescope wasn’t good enough to get a good look at something that seemed very different from anything he'd seen until that time. He described Saturn as "triune," mistaking the rings for two moons that seemed to orbit 180 degrees from each other, giving the appearance of ears on the planet.

In 1609, when Galileo first turned his new astronomical telescope on the night sky, Saturn was just a bright point in a black sky -- so unremarkable that a year passed before he turned his new instrument at it. But he finally gave Saturn his attention on July 25, 1610 -- a monumental date in planetary study because, from that night forward, Saturn gripped his imagination. 

About 50 years passed before Saturn’s rings came into focus for Dutch astronomer Christiaan Huygens. He described them a flat, circular disk. Something altogether different from anything he and Galileo had ever seen or expected to see. It was truly unearthly.

Today, NASA's Cassini spacecraft, orbiting Saturn since July 2004, inundates researchers with remarkable new data… about the planet and its rings and moons… the plumes of dust venting from cracks in the surface of the moon Enceladus… sunlight reflecting off a lake on Titan… flashes of meteorites hitting the rings. Thanks to Cassini, Saturn continues to amaze.

Tamas Gombosi is the Rollin M. Gerstacker Professor of Engineering and chair of Michigan Engineering's Department of Atmospheric, Oceanic and Space Sciences. He has a lot to say about Cassini and what it's taught scientists about Saturn's space environment. 


You can also learn about Saturn and Cassini at the NASA site dedicated to the spacecraft's mission.