Saturn has been described as “astrophysics become art”, and judging by the image of Saturn as seen through a 12-inch reflecting telescope shown below, it is not hard to see why. The planet has a certain “regal” air about it, and while it is possible to see some of its rich detail through binoculars and retail telescopes, this magnificent planet really only becomes breathtaking when viewed with medium to large instruments. Here is how to see Saturn at its absolute best.
Although the best time to view Saturn has passed (opposition occurred on June 3rd 2016), there is still opportunity for observers in the UK to view the ringed planet. For instance, during early September, Saturn sets at about 22:50 Local Time as seen from London.
Finding Saturn is not difficult; with the naked eye, it looks like a fat golden star near Mars and the star Antares, in the constellation Ophiuchus. Note however that Saturn is close to the horizon, and observers in the far northern UK might therefore not be able to see the planet at its best through the thick atmosphere near the horizon.
Nonetheless, look for Saturn at one corner of a very conspicuous triangle formed by Saturn, Mars, and Antares. Under really dark skies, it should now be possible to see Mars and Saturn on opposite sides of the Crown of the Scorpion, an arc of three stars near Antares, the heart of the Scorpion.
As with all planets, Saturn is best seen at opposition, when it is directly between Earth and the Sun, and therefore at its point of closest approach to Earth. The next two dates of opposition will be on June 15th 2017, and June 27th, 2018. In the meantime, though, Saturn will remain a conspicuous early evening object until October 2016.
Consider the image above; the view in the background approximates the best possible view of Saturn under near perfect seeing conditions through a 4-inch telescope, while the foreground image is close to what can be expected through an 8-inch instrument under similar conditions. However, obtaining clear views of Saturn through a telescope has much more to do with local seeing conditions than both instrument aperture and/or magnification.
The reason for this is the fact that Saturn has low colour contrasts. In practice, this means that fine details are easily washed out by atmospheric turbulence, which is magnified along with the image at high magnifications. In really bad seeing conditions, images of Saturn can be so unstable that it looks like the observer is seeing the planet through a layer of running water.
The trick to observing Saturn lies in the three “P’s” of amateur observing- Patience, Practice, and Perseverance. For instance, if seeing conditions are less than perfect, it might still be possible to observe other planets or even deep sky objects, but this does not work with Saturn. Therefore, be patient and wait for perfect seeing conditions, be persistent in your efforts to view Saturn, and when seeing conditions improve, even momentarily, practice observing techniques by experimenting with magnifications and filters to get the best views.
As a general rule, magnifications of between 150 × and 250 × work well in combination with yellow eyepiece filters in large instruments, but less well on smaller instruments because filters tend to dim views of Saturn in small telescopes.
What to expect
The image of Saturn above was taken by the Voyager 1 spacecraft from a distance of about 1.6 million kms, and while it is possible to obtain excellent images of the ringed planet with ground based telescopes, do not expect to achieve the resolution of this image. However, it helps to have an idea of what to look for when observing Saturn, and in 2016, amateur observers can expect to see the ring system almost as it is shown here, inclined towards out line of sight by 26.5 or so degrees. This angle will increase to 27 degrees by 2017.
While the broad gap between the “A” and “B” rings – the Cassini Division – is easily resolved even in modest telescopes, the much narrower Encke Division is a true challenge even for large instruments under excellent seeing conditions. Nonetheless, since the ring system is favourably tilted, its inclination offers an excellent opportunity to experiment with various filters and magnifications to try and “split” the subtle colour differences between various parts of the ring system, but be aware that the best that can often be hoped for is to resolve the Cassini Division when the planet is close to the horizon.
Observing Saturn’s moons
Resolving fine detail on Saturn is as much an art as it is a science, and the novice observer might find it more profitable to observe Saturn’s’ larger moons when seeing conditions are less than ideal.
The image above was created by a free software program , and it shows the actual positions of five of Saturn’s moons at 20:20 on September 4th, 2016. Note however that while the largest moon, Titan, can be seen with a 2-inch telescope, at least a six-inch instrument is needed to spot the moons Iapetus, Rhea, Dione, but with a little perseverance, it might be possible to spot Tethys as well. Note that to spot the moon Enceladus, a ten-inch instrument is required.
Simply by entering the date, time, and type of telescope into the program, an observer gets an instant plot of the moons and by altering the time zone offset, the moons’ positions can be animated to reflect their relative positions over the length of the planned observing session. Being able to predict the positions of Saturn’s moons adds a lot to any observation of the planet, so go ahead and try it- you’ll be glad you did!