The Lake County Astronomical Society

Saturn's Rings - GONE!

Dave Wagner

What a tragic headline that would make! When it comes to beauty in the heavens, there are few finer sights than Saturn and it's rings. Accessible to every size and shape of telescope, a hit at any star party, a wonder still not fully understood.

And while many scientists estimate Saturn's ring system has endured for over 100 million years, for us on this blue orb those gorgeous rings will be gone this time next year.

Tell me it's not so! Ok, Ok, the sky is not falling and the rings will be there at least until after re-runs of CSI have traveled well beyond the edges of our galaxy. You probably knew that already. But what many of the general public and probably those who are new to astronomy do not know, is that the rings will slowly 'disappear' next year, or at least lose their broad prominence and grandeur as the rings face 'edge on' to earth bound eyes in 2009.

From the start - While the existence of Saturn was known from pre-historic times, it's rings were not recognized as such until 1659 when Christian Huygens correctly inferred the geometry of the rings. Galileo was the first to observe Saturn through his small, low-resolution telescope in 1610, but the oblique shape confused the observations. In 1612 Galileo was further confounded when that odd shape went back to being round. (I can only imagine Galileo just finishing a cleaning on his telescope in 1612, and after observing Saturn was finally a properly round planet, tossing into the trash the last 2 years of observing notes on Saturn...).

Perhaps my first view of Saturn was not so different than what Galileo had experienced almost 400 years earlier. New to the hobby, I had swung my very new and capable SCT telescope via GO-TO command to take in my first sighting of the ringed planet. To say the least, I was confounded. All I could see was an unrecognizable oblongish blob of light in the sky. I didn't realize at the time the tremendous distortion that can be caused when looking low to the horizon by all the atmospheric movement. (Like I said, I was a bit the newbie).

Mechanics - Just like earth, Saturn is tilted on its axis to its plane of the orbit about the sun (27 degrees, versus the 23 degree tilt of the earth). Just as that tilt provides each hemisphere on earth with it's chance to angle towards the sun (providing our seasons), Saturn's tilt does the same. For the last 14 years we have had Saturn's southern hemisphere primarily facing our direction. As a result we have been looking only at the underside of Saturn's rings. As the planet reaches it's equinox, when we'll see both hemispheres equally, the ultra thin rings will be 'edge' on to observers on the our planet. When looking edge on to a thin blade, the blade basically disappears from sight. In 2009, when the rings go edge on to our view, they too will be GONE from our view.

Take a look at the sequence photo of Saturn each year at opposition. It goes from southern exposure in 2001, to edge on in 2009, then to northern exposure peaking in 2017, returning to edge on in 2025, and finishing after nearly one full orbit in 2029, with a southern exposure.

If my Astromist software is accurate (Assistant, Saturn, Rings - is the menu sequence to reach the ring angle viewer for you Astromist users out there), then in January of 2009 the rings will be tilted only 0.3 degrees from edge on to our view. Probably worth a look just to see IF we can see the rings. The ring angle will widen some (as earth changes it's angle to Saturn), but the rings will eventually return to edge on to our view in September 2009. It won't matter by then though, as Saturn will be lost in the glare of the setting sun when the rings pass through 0 degrees to our view. Any way you slice it, the rings will be at their least viewable and least spectacular angle for all of 2009. And 2010?? Not that much better. During opposition we'll get maybe 4 degrees of angle at opposition, about 1/2 of the angle we'll see at opposition this month. It's going to be a long dry spell for viewing the rings.

Bottom Line -Make hay while the sun shines, get going while the going is good, eat while the food is hot, limited time offer, so get yours while supplies last! Get a memorable view of those rings real soon, because it will be a longgggg wait until we can get those glorious wide angle views of the ringed planet again. Don't miss it!