Tuesday, December 16, 2003

Return of the Rings

Return of the Rings
by Dave Adalian

Somewhere in the cold and empty void beyond the orbit of Jupiter a spacecraft is racing toward a long-awaited rendezvous.

Seven years ago NASA and the European Space Agency’s Cassini-Huygens Mission to Saturn left Earth. Twice it swung past Venus, once returned by Earth, and finally it flew past Jupiter on the way to its destination. Cassini is scheduled to enter orbit around the ringed gas-giant planet on July 1 of next year.

When the probe arrives, it will transmit back to Earth new information about the ringed world and its largest moon, Titan. Titan is the only moon in the Solar System with a thick, planet-like atmosphere, and the Huygens portion of the probe will drop below it to the surface to see for the first time what lies underneath. Perhaps lakes or oceans of liquid methane.

Potentially glorious pictures of Saturn’s 150,000-mile wide rings, its stormy atmosphere and the other lesser moons will also be captured by Cassini--the most complicated robotic probe mankind has built.

As intellectually stimulating, scientifically important and just plain exciting as that is, all the images and data in the world don’t rival viewing Saturn with one’s own eyes as it moves through the night. Now through March is the best time for doing just that.

Saturn seems to know 2004 is its year, and is planning a New Year’s celebration. Like Mars before it last August, Saturn is coming to opposition--the time of year when it appears to be opposite the Sun in the sky and is closest to Earth--on New Year’s Eve.

Because it is at opposition, Saturn rises on Dec. 31 as the Sun sets, around 4:45 p.m.

By 9 o’clock it is well up in the east, shining bright yellow from its perch in the zodiacal constellation Gemini. To Saturn’s left are the twin stars Castor and, slightly east, Pollux.

As the year turns at midnight, Saturn appears to be on the imaginary meridian line joining north pole to south, signaling our longitude--119 degrees west--is at its closest to the ringed planet for this pass. Saturn is about 800 million miles away.

This view is made truly spectacular by the current angle of Saturn’s rings, almost completely open toward Earth. A telescope will show the rings and perhaps details within them. If you haven’t got a telescope, find someone who does. It’s worth the effort.


This column originally appeared in the Visalia (Calif.) Times-Delta on Dec. 16, 2003.