Caoimhín's Content

Now that Saturn is returning to the early morning sky, even becoming visible to the naked eye in the city, we are going to take a closer look at the planet. It is still tricky to see from higher latitudes, but as long as you are up early enough and have a clear view of the Southeastern horizon, it is there to be seen. When it first appears over the horizon, at close to 4:30 in the morning, the sky is still reasonably dark, with only a trace of sunrise glow beginning to show. However, when we are looking at an object low to the horizon, we are looking through more of the Earths atmosphere to see it. This cause the object to appear fainter, it is reduced or extincted. Saturn should be magnitude 1 under good conditions, but so low to the horizon its reduced nearly to magnitude 4. As Saturn rises in the sky it will appear to get brighter, but so will the sky itself as the orange glow of sunrise really begins to take over. Saturn rises up to about magnitude 2 before the glow of sunrise causes it to fade to nothing by just about 5:10. At the moment, we have just about 40 minutes in the morning where we can see Saturn.

Thankfully this is going to change, Saturn will rise earlier and earlier until we’re seeing it for the whole night by late September into early October. Of course the Sun continue rise earlier as well as we move into summertime. Even so, Saturn will push further and further from the Sun in our sky, giving it a chance to reach a reasonable height while the sky is still dark in just a month or so. Then, it will be perfectly fine to observe it with a telescope, but during the month of May it is still going to be a little bit too close to the bright light of the Sun. It is certainly too bright to safely use a telescope, of course you can just use your naked eye to spot Saturn, and by the end of May Saturn is reasonably close to a Waning Crescent Moon which looks pretty nice. By then we will also just about be able to see Mars in the city, but it will remain much harder to observe than Saturn.

Taking a closer look at the Ringed Planet, don’t need a particularly big telescope, even a reasonably small telescope will begin to show you Titan, Saturn’s largest moon, as long as it’s in the right position. Titan has a thick atmosphere that gives it a distinct orange colour and reflects a lot of light, making it bright and clear even next to the massive planet Saturn. With a slightly ,more powerful telescope we’ll begin to see Saturn’s Ring, and in May and for much of this year, it will appear very inclined, we’ll be seeing it almost edge on. This changes over the course of the year as well, mostly due to Saturn’s movement, so it will change gradually over the 29 Earth-year long orbit of Saturn, more so than in one Earth year. Saturn has an axial tilt similar to the Earth and sometimes we see it tilted towards us letting us see the rings at an angle, which lets us see more of their surface area. We will get to see Saturn a bit more tilted later in the year, but in the beginning of the year, the ring almost looks like a straight line, making it a bit harder to spot. Even if your telescope is too weak to see the colour of Saturn itself or any of its faint stripes, you might still see the rings sticking out from either side of the planet, you still don’t need a very big telescope.

If you do have a slightly bigger telescope, you should see a few more of Saturn’s moons. Saturn has over 100 moons, but most of them are very very small and difficult to observe. Only a handful of Saturn’s moons are large enough for us to easily see, Titan in particular. The atmosphere of Titan reflects light just like the atmosphere of Venus, and similarly obscured its surface making it hard to study from the Earth. Unlike Venus, the atmosphere doesn’t make it incredibly hot, as it is soo far from the Sun. The temperature on Titan is often well under negative 100 degrees Celsius, about -175 degrees. The obscuring clouds in the atmosphere are liquid, or vapour, methane, ethane and other organic compounds, little droplets suspended in an atmosphere that is mostly nitrogen, more so even than our own. These gasses are often called natural gasses here on Earth, especially when we use them for fuel, but they are only called organic because they have a lot of carbon in them, they are not necessarily created by biological activity. Although we can’t see the surface of Titan, a probe has landed on its surface and sent pictures home, so we do know a little about the surface, including how the methane and ethane clouds rain down into methane lakes which then evaporate back into clouds, similar to the Earths water cycle.

Early in May, with a very big telescope, we can see the shadow of Saturn stretching back onto the ring. We only get to see this clearly when Saturn is close to sunrise or sunset, it is less obvious when Saturn is at opposition. Of course, this means we can only see a large portion ogf shadow when Saturn is up for a shorter amount of the night, as well as being further from us and fainter. When we see Saturn in the middle of the night, at opposition, then it is directly behind the Earth relative to the Sun. This puts the shadow of Saturn directly behind it, still falling on the ring, but on a part that we can’t see thanks to the planet in the way. There is a previous article on this website and video on my YouTube channel, where we look at Saturn’s ring from the planet itself, giving you a chance to see the shadow of Saturn passing over Saturn’s Ring from the upper atmosphere of Saturn.

A more powerful telescope will also show you a few more of the smaller moons, the ones that are close to the ring system. Many of Saturn’s smaller moons orbit further from the planet, even further than Titan, which makes them much harder to see, most of them were only discovered recently. The small moons close to the planet are a lot easier to see by accident, as they will be in your view when you look at Saturn itself. Pan is one example of a very small moon, a little lumpy ball of rock, just outside the visible ring. Small moons like Pan and Janus that are close to the ring help to keep it in shape and are known as shepherd moons. Atlas, a small moon very close to the edge of one of the bright rings, looks like it should be a shepherd moon, but it is so small it has less of an effect than the slightly more distant Janus. Looking at something so distant under high magnification, even if you are just looking at the planet Saturn, the rotation of the Earth has a pretty big effect and it can make Saturn drift out of your view quite quickly. Motorized telescopes, that can match the speed of the Earth and keep objects in view even as they drift across the sky, are a big help if you are looking at something small under high magnification. A slewing telescope is one that can move in such a way, though they will often slew to their target object as well, then track it through the sky.

That’s when you’re looking at the real plant over the course of a night, when you’re jumping through days in a piece of software, the planet jumps a bit through the sky each day, so you need to stay locked on the planet if you’re using a piece of software like Stellarium. With a slightly less zoomed in view of Saturn we can see Enceladus, which is a particularly interesting moon because it is an icy moon. Icy moons are moons that have a lot of ice on them and in the case of Enceladus, and also moons like Europa, underneath the shell of ice there is liquid water. Liquid water seems to be one of the main ingredients for life as we know it, we usually only find life where we find water. Life can survive without oxygen or without Sun light, but usually there’s some water involved if any thing is respiring and living. Some creatures need very little water, or can survive long periods without it, but all life discovered so far needs at least a little water to function. For this reason, moons like Enceladus that have a lot water under their icy shell are very promising locations to search for life in our solar system. We don’t see it from the Earth, but there is a very faint outer ring around Saturn, outside the bright inner rings that we see, generated by Enceladus. Enceladus spews little bits of water and ice into space, a phenomenon known as cryovolcanism. The water doesn’t erupt like it would from a geyser here on Earth, but is rather sucked out of cracks in the icy shell by the vacuum of space. That little bit of water and ice shooting out into space forms a very thin faint ring around Saturn, it’s similar to the faint ring around Jupiter would have, at least in that we don’t normally see it from the Earth, the rings around the other gas giants and the ice giants Neptune and Uranus, are much fainter than the bright rings of Saturn.

Once Saturn is at opposition, we’ll see it in the middle of the sky in the middle of the night, just like a Full Moon, and it will stick with us for the entire night in the same way. This is also when we’re at our closest to the planet and when it’s going to look it brightest. This generally makes it the best time to observe the planet with a telescope. This year, Saturn will reach opposition during northern Winter, so it will reach its highest at 12 o;’ clock, we won’t have to worry about daylight savings potentially complicating things. As Saturn is orbiting the Sun slower than the Earth, we catch up to it in order to form a direct line with the Sun, and then begin to move away from it. This gives Saturn a similar loop to its apparent motion as Mars, meaning it hangs roughly around its opposition point in the sky for a while, we should see this happen as we come up to October. By then we will be able to see the rings a bit more clearly, as Saturn will be tilted more relative to the Earth. Close to the exact position of opposition, the shadow of Saturn is pretty much invisible from the Earth, lining up with the planet Saturn. There also appears to be a moment where Titan is almost directly behind the planet, but still visible above Saturn through a sufficiently high powered telescope, which certainly provides a nice view of the pair. You may also can see faint stripes on Saturn, Saturn does have a stripy atmosphere similar to Jupiter but the stripes aren’t as bold or clearly defined. Saturn also has a very short day, at a little over 10 hours it is rotating a little bit slower than Jupiter but still a lot faster than the Earth. This means, just like with Jupiter, that if you go out at the same time a few nights in a row, you will see different sides of the planet. However, it’s pretty hard to tell as there are so few distinct features. We don’t have massive, obvious storms to help us tell the different sides apart, as we do with Jupiter.

This ha been, of course, just a very brief look at Saturn. We know where it is at the moment and when to see it, as well as how it will appear later in the year and when it reaches its optimum viewing position. There is still plenty left to say about Saturn, and it is a particularly nice target with a telescope, where you can see the moons, particularly Titan, even with a low power telescope, you don’t need anything crazy if you’re looking at Saturn in the sky. For right now, I do still need to warn you not to point a telescope at Saturn for maybe another month, as it is still very close to the glow of sunrise. We’ll have to wait until we’re a little further into to summer time, but hopefully you’ll get you’ll get a chance to take a closer look at Saturn then, and I will almost certainly be saying more about it when it’s in a better position. If you don’t want to miss out on up-to-date information on Saturn as it progresses along the sky, you can subscribe to this website or my YouTube channel or both. It will be a while before I get back around to Saturn specifically, but there are plenty of other interesting objects in the sky, including the comet I’ll be discussing next time, so I hope to see you back here then.