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Today, we are going to be taking a look at Titan, Saturn’s largest moon. We may take a look at a couple of other moons as well, but Saturn’s moons are more reasonably visible at this time of the year than Jupiters. Around the middle of the month, the Moon is pretty close to Saturn, and pretty close to full. We’re going to move a little bit closer to the end of the month to get the Moon out of the way. Saturn rises soon after sunset, but it’s nice and high early in the morning, around 3 o’clock. Saturn is not quite at its highest at that time, but it is darkest. If we push later in the night, Saturn starts vanishing just before it reaches due south. Once the glow of sunrise starts to come into the sky, using a telescope or binoculars to see anything in greater detail is going to be a lot more difficult. We’ll stick with true darkness, we’ll say 2:45 in the morning and much later in the month, on the 26th of July.

Once we start taking a closer look towards Saturn, Neptune may also be visible, as Saturn and Neptune are very close together at the moment. Neptune may be visible as a slightly bluish dot, but even under a lot of magnification it is difficult to distinguish from a star. Focusing on Saturn, the moon Iapetus gets labeled even while it is difficult to see. Iapetus is a lot smaller and fainter than Titan, but it is also further from Saturn. Iapetus is a very faint dot next to Saturn, while Titan appears to be budding off of Saturn, bigger and brighter but barely separate under the same level of zoom. Titan is visible as a separate object even before we can see Saturn’s rings, but at that level of magnification, Titan will blend in with Saturn in certain positions. We need to move through a few dates to get Titan in the right position to be seen if we are using lower power telescopes. Moving back in time we would see an increase in brightness, a sign that the Moon is nearby in the sky. Titan is visible even with, I hesitate to say even with binoculars, but Titan is certainly visible with a lower power telescope. Even if your telescope is too low a power to see Saturn’s rings, Titan should still be visible, but with binoculars it’s difficult to see Titan even if it is in the right position. With Titan at the edge of the disc of Saturn, it is barely visible through binoculars, we’ll certainly have to go up to a telescope of some sort.

Titan is visible, distinct from Saturn, even if your telescope isn’t powerful enough to see Saturn’s rings, although this will vary on the day. We can see Titan sticking out to the side from here in Ireland on the 22nd. The 22nd and the 23rd seem to be the best dates to see Titan from here. However, once Titan is close to lining up with Saturn either in front of it or behind it, then Titan will be invisible with lower magnifications. As we start zooming in closer, we start getting a view of some of Saturn’s other moons and Titan’s size becomes much more apparent. Titan is huge compared to the other moons of Saturn, but even more importantly, Titan is significantly brighter than those other moons. We’re seeing Titan at around magnitude 8.4, so it’s certainly out of view to the naked eye. 8th magnitude, reduced to magnitude 8.7 by the atmosphere, is quite bright. If Titan was in a completely isolated part of the sky, it would reliably be visible with telescopes. Unfortunately, we always see Titan right next to Saturn. Here we have Saturn at a 0.85 magnitude, and Saturn is usually hovering around 1st magnitude, easily outshining the practically 9th magnitude moon next to it. Saturn’s other large moons are even fainter, 9.79 for Rhea, Tethys and Dione at about 10, and Enceladus at 11.78.

Enceladus is considered to be an icy moon, and you may remember from some previous videos, icy moons are considered some of the most likely to harbor life. If a moon has an icy shell on the outside, there’s a good chance that volcanic activity, created by the gravitational pull of its parent planet, is occurring under the shell of ice, thawing some of the ice into water. Water, of course, is one of the main things that we associate with life, certainly all life that we’ve discovered here on Earth has a close relationship to water. Titan is different. If we take a closer look at Titan, all we’re going to see is a fluffy atmosphere, this thick atmosphere of methane and ethane. A lot of Titan’s atmosphere is nitrogen, but that’s not the visible orange part, those are clouds of methane and ethane. These are simple hydrocarbons, a carbon atom or two with a few hydrogens stuck on the side. Underneath these clouds, those hydrocarbons rain down as liquid, gathering up in lakes and flowing as rivers. They eventually evaporate again back up into these clouds, in a cycle very similar to our water cycle. Titan has a lot of hydrocarbons and hydrocarbons are one of the building blocks of carbon based life. Carbon can form multiple bonds of multiple shapes, allowing it to bond to multiple hydrogens, multiple oxygens and multiple other carbon atoms. Titan certainly doesn’t have any atmospheric oxygen just floating around the place, but having the amount of hydrocarbons that it has, that’s made Titan a very interesting and potentially promising candidate for life in our solar system.

All of the icy moons, like Enceladus around Saturn, and Callisto around Jupiter, these other icy moons are full of water. For that reason, we’re expecting any life that we find living in that water to be reasonably similar to life on Earth, using water as its primary solvent. Whereas on Titan, methane and ethane are the common liquids, and other liquid hydrocarbons down on the surface. If we find any life on Titan, it’s more likely that it will use those liquid hydrocarbons as its solvent. Using a different solvent is a big difference in the way that life functions. We use water as a solvent for life here on Earth, so water is a very important part of our diet, we need to drink a lot of water to stay alive, and we generally find organisms living in places with some amount of water. Those life forms that can live in very dry areas, they very often hibernate or aestivate, they go into a state of dormancy when it’s too dry. It’s called a tun state in the case of tardigrades, if they get too dry or things get too cold and all of the water freezes, they allow themselves to dry out and go into stasis until the water comes back. Titan is too cold for liquid water, so that’s not an option for potential life. If we find life that can use something like methane or ethane as a solvent instead, it brings up the possibility that life can be very different from the life that we expect here on Earth.

Looking at the broader morning sky, we can see the very bright Venus between the sunrise and Saturn. Just above the sunrise is the Moon with that nice orange-yellow glow because it’s so close to sunrise. We’re looking at the sky on the 23rd of July at just about 4:30 in the morning. JUst below the Moon is Jupiter. If we take a closer look at Jupiter, we’re going to see Jupiter’s largest moons, the Galilean moons. Callisto is out at the west side, Io is a little closer to Jupiter. Io of course is covered in volcanic activity, we don’t expect to find much liquid water there, so of course not much life. We can see Ganymede near Io and out the eastern side is Europa. We can also see that these moons are quite bright. They are a lot closer to us than the moons that are orbiting Saturn, but the iciness of these moons contributes to their brightness. Ice is very reflective, so it gives these moons a reasonably high albedo. In Stellarium, albedo is not a factor that is listed on the side with the other details of the selected object. We don’t see albedo as a factor there, but many of these moons do have a high albedo. Each of them except Io basically, they’re all considered to be icy moons. Europa, Ganymede and Callisto, they’re all moons that have a shell of ice. Some of them show evidence of cryovolcanism, where liquid water spurts out from their icy shells. This is of course a really good sign that they have liquid water under those icy shells, we almost certainly wouldn’t see liquid water spurting out if there wasn’t liquid water there to be compressed in the first place.

Saturn has an icy moon, Enceladus, and it also has this “atmosphered” moon, Titan. As such, Saturn in particular is an interesting possibility for the chances of life. Saturn also has a much weaker electromagnetic field than Jupiter. the electromagnetic field of Jupiter is incredibly powerful, so the moons that exist within that field are going to be bombarded by high energy particles from the Sun caught in that magnetic field. Saturn’s magnetic field is weaker and it’s further from the Sun, so that isn’t as much of an issue. On Enceladus, it is an icy moon, so we can maybe expect life that uses water in a similar way to life here on Earth. Titan on the other hand, due to its methane/ethane atmosphere, if there is anything living on Titan, it will be living in a very different biosphere, and that is promising. It would be very interesting to find life on Titan because it would show that life can be very different from the kind of life that we expect here on Earth, and it would broaden our options when it comes to looking for life in other places. If life survives on a planet like Earth and on a moon like Titan, that opens up multiple options for where life could exist elsewhere in the universe.

I hope that you enjoyed this piece, just talking a little bit about Titan, the icy moons, and the potential for life existing on them, the reason that it’s important, and why Titan is so interesting. It is this very, very different moon, if there is a biosphere there, it would be very different. If you did enjoy this piece then please do like it. If you enjoy this kind of content, then you can subscribe to this website and my YouTube channel. Hopefully I’ll see you back here next time.