Centaur
25-February-2009, 01:49 AM
The beautiful ringed planet Saturn will appear in opposition to the Sun on 2009 MAR 08 at a distance of 8.394 AU from the Earth. At that time its celestial magnitude will be +0.5, and it will have an equatorial angular diameter of 19.7 arcseconds. Its rings will appear tilted 2.6° to our line of sight.
Saturn is currently in apparent retrograde motion; apparent direct motion will resume on MAY 16. Eastern quadrature (90° from Sun) will come on JUN 06, before conjunction with the Sun on SEP 17.
As Saturn 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 AUG 10.
The rings appear rather narrow right now, but will widen a bit while the planet remains in retrograde motion and then resume narrowing afterward. 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 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 year and over a period of thirty years. They can be seen by clicking: http://www.curtrenz.com/astronomical.html
Photos and descriptions of Saturn and its rings would be welcome additions to this thread.
Saturn is currently in apparent retrograde motion; apparent direct motion will resume on MAY 16. Eastern quadrature (90° from Sun) will come on JUN 06, before conjunction with the Sun on SEP 17.
As Saturn 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 AUG 10.
The rings appear rather narrow right now, but will widen a bit while the planet remains in retrograde motion and then resume narrowing afterward. 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 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 year and over a period of thirty years. They can be seen by clicking: http://www.curtrenz.com/astronomical.html
Photos and descriptions of Saturn and its rings would be welcome additions to this thread.