Post by Centaur on Jul 31, 2009 12:04:52 GMT -6
Saturn’s rings are about to disappear! As that planet orbits the Sun we view its rings from changing perspectives. The rings remain virtually parallel to an invariant plane, but they appear to wobble due to the changing direction from which we view them. The entire wobble cycle matches Saturn’s orbital period of 29.5 years, although there is an annual sub-cycle due to the Earth’s movement. The apparent tilt achieved a maximum of 27.0° on 2003 APR 07. That will reach zero when we pass through the ring plane on 2009 SEP 04, although the Sun will pass through the plane a little earlier on 2009 AUG 10.
Between the dates of the Sun’s and the Earth’s passages through the ring plane, we will be viewing the unlit side of the rings thus making them virtually invisible. Even though the rings would normally return to visibility after we pass through the ring plane, that event will occur so close to conjunction with the Sun that Saturn will be hard to detect. That will be especially true for northern hemisphere observers due to the celestial geometry near the time of the autumnal equinox.
On my website are two graphics I’ve created to illustrate the appearance of Saturn and its rings both this summer and over a period of thirty years. They can be seen by clicking: www.curtrenz.com/astronomical
Photos and descriptions of Saturn and its rings would be welcome additions to this thread.
Between the dates of the Sun’s and the Earth’s passages through the ring plane, we will be viewing the unlit side of the rings thus making them virtually invisible. Even though the rings would normally return to visibility after we pass through the ring plane, that event will occur so close to conjunction with the Sun that Saturn will be hard to detect. That will be especially true for northern hemisphere observers due to the celestial geometry near the time of the autumnal equinox.
On my website are two graphics I’ve created to illustrate the appearance of Saturn and its rings both this summer and over a period of thirty years. They can be seen by clicking: www.curtrenz.com/astronomical
Photos and descriptions of Saturn and its rings would be welcome additions to this thread.
