Friday, 28 February 2014


Big beautiful Saturn, complete with its astonishing set of rings. The Cassini Division is the black radial where astronomers believe a moon has cleared out the icy debris via its gravity. Image courtesy of NASA/JPL Cassini Imaging Team.


If there is one celestial object that is both readily visible in even the worst light polluted skies, and yet full of the astronomical “wow” factor, it has to be Saturn, our solar system’s beautiful ringed gas giant planet.

For anyone new to telescopic observing, Saturn is usually an early and easy target. The planet has fascinated me for a long time, revealing an interesting bright disk when viewed through my 10x50 binoculars, but definite and tantalising “handles” or “ears” when viewed with some old 12x50s - very much in accordance with Galileo’s findings in the early seventeenth century. It yearns for greater magnification.

Saturn is like an old friend to me, both often gracing our skies and never failing to impress when other planets, like Mars, often fail. Having had an hour observing the Moon, I simply couldn’t wait any longer to observe Saturn with my 200mm Dobsonian. Like most people, when I first observed Saturn I was unprepared for the awesome views of the planet as revealed through a large, quality telescope with a sturdy mount.
Through a 26mm Plossl eyepiece, the planet is small, very bright, with clearly visible rings, and at least one of its family of moons is visible (Titan, of course).

Titan, a world where science fiction
meets science fact. This photograph
of its boulder strewn surface was
taken by ESA's Huygens lander whilst
 NASA's Cassini spacecraft
orbited the Saturnian system.
Using the x2 Barlow and Plossl, the whole system becomes much more striking, with another couple of specks of moons coming into view (Rhea, the planet’s second largest and Tethys). Saturn has a family of nearly sixty moons in tow, and to really enjoy this “mini solar system” it was time to put a 9mm eyepiece through its paces, when the Cassini Division and the A and B rings came clearly into view. Close inspection of the planet itself shows a slight shadow on the disc, cast by its beautiful ring system. There are a few cloud bandings visible on the
planet’s disc – these bands however, are much less pronounced than those of Jupiter.

It is truly amazing to think, as you view the solar system’s second largest planet that it is a staggering 1.3 billion kilometers away – indeed the light reaching your eyes from Saturn has taken over an hour and a half to reach Earth. It kind of gives you some idea of astronomical distances, as in cosmic terms, Saturn isn’t even next door – it’s in another room in our house!

Returning to its moons, the largest, Titan has already been visited by a robotic emissary from Earth, in the form of the ESA Huygens lander, which along with NASA’s Cassini spacecraft has revealed an amazing world of orange skies, ice rock, mountains and possible liquid ethane lakes, that starting with the great Carl Sagan has fascinated astronomers for years. This enigmatic tiny little world appears to have a definite brownish hue through the telescope using the Barlow and 9mm eyepiece , due to its bizarre hydrocarbon atmosphere. Indeed, it is the only moon in the Solar system with a dense atmosphere (ten times as dense as that of the Earth) – a pre-biotic atmosphere of tholins in icy stasis – an almost an
Earth atmosphere, frozen in time before life got going.

Titan has weather too – it rains liquid ethane and methane on Titan – yes it’s that cold! Observing Titan, you envisage those boulders and rocks of solid ice from the Huygens photographs, and you think about Cassini’s scans of this tiny world. You suddenly realise Titan is not just a small disk in your telescope - it’s a place - we’ve been to Titan!

The air is starting to chill, but before I pack away the equipment, I observe other minute specks of light around Saturn. Averted vision shows them to be even brighter – they are more of Saturn’s family of moons, including Rhea and Tethys again, and Dione and possibly Enceladus – the Ying Yang moon! I think of venting water and ice inhaled by Cassini, and I wonder how liquid water possibly exists within such a deep freeze as the Saturnian system. I think of Cassini’s evidence for a deep subsurface water ocean on Titan, kept liquid by the immense gravitational tidal forces of Saturn. And I think how the Lord of the Rings has
wonders aplenty to keep mankind busy for years to come.


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