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September 2008: Saturn Returns, but Rings to Disappear

On September 4, 2008, the planet Saturn will pass behind the Sun, transitioning from the evening to the morning sky. By late September, people living at mid and far northern latitudes should be able to catch Saturn in the dawn and predawn sky, as this world will be rising well over an hour before sunrise. To know the rising time for the Sun and Saturn in your sky, check the links at Earth & Sky's almanac page.
On the morning of September 27, watch the waning crescent Moon pair up with Saturn.
As Saturn climbs higher and becomes more prevalent in the morning sky, its rings will narrow until appearing almost edge-on in December 2008. In 2009 the rings will open again slightly, but will appear completely edge-on by September 4, 2009. We see Saturn's rings edge-on from Earth whenever Saturn is appreciably close to its equinox.
Saturn's rings were last edge-on as seen from from Earth on February 11, 1996. Ever since that time, we've been looking at the southern side of Saturn's rings. Saturn's southern hemisphere was most titled our way on April 7, 2003. Because Saturn's rotational axis is tilted about 27 degrees out of perpendicular with the plane of the ecliptic (Earth's orbital plane), Saturn's south pole was tilted 27 degrees toward Earth in 2003. Saturn's rings appear most open to us when Saturn is appreciably close to one of its solstices.

Saturn's Rings: Good Reflector of Sunlight

Because Saturn's rings better reflect sunlight than the planet itself, the ringed planet will be about 2.5 times fainter in 2009 (when the rings are edge-on) than it was in 2003 (when the rings were most open). But don't despair! This is your chance to see Titan - Saturn's largest moon and the second largest in the solar system - swinging in front of and behind the ringed planet.
According to Jean Meeus (page 197 of More Mathematical astronomy Morsels): "Titan will start with a shadow transit on 2009 February 24, followed by the first eclipse half a revolution later, on March 4. The last eclipse will occur on 2010 January 1, and the last shadow transit a half revolution later, on January 9. The series will contain 20 eclipses and 21 shadow transits of Titan."

A View of Saturn's Northern Side

After Saturn's rings appear edge-on from Earth on September 4, 2009, we'll see the northern side of Saturn's rings until March 23, 2025. The rings will be most titled toward Earth on October 16, 2017.

Saturn's Rings and the Zodiac

When Saturn's rings appear edge-on as our view of the rings shifts from south to north (2009, 2039) Saturn resides quite close to the border of the constellations Leo and Virgo. When our view appears edge-on as the rings shift from north to south (1995, 2025) Saturn lodges nearby the border of the constellations Aquarius and Pisces. The northern side of Saturn's rings appear most open (1988, 2017) when Saturn is north of Scorpius' tail; and southern side of the rings appear most open (2003, 2032) when Saturn resides in front of the horns of Taurus the Bull.

copyright 2008 by Bruce McClure

Saturn and Titan from New Zealand
Resources:
Guy Ottewell's Astronomical Calendar 2008, page 54
More Astronomical Astronomy Morsels by Jean Meeus, pages 195-197, 292-298

August 2008 Feature * October 2008 Feature