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Today, we are going to be taking a look at the planet Saturn. At the moment you can catch it just a little after sunset towards the east. Here in Ireland we can see it by about 9 o’clock in the middle of September. We’re going all the way forward to the 20th of September, which is roughly when Saturn will be at its opposition. Saturn comes to opposition every year, because opposition is just when Saturn is on the opposite side of the Earth to the Sun.

Looking at Saturn at its opposition, it’s illuminated 100% and its distance from the Earth is 8.547 AU, the least it will be this year. I went through this when we looked at the opposition in a previous piece, but we will be looking at some other things as well. Saturn’s around its closest for a few days around the opposition. AU or Astronomical Units are a very large unit, so the distance in millions of kilometers will be a little bit more accurate. Just after midnight on the 20th, 1:30 in the morning of the 21st, is when the distance is at its lowest, 1,278.576 million kilometers. We will see Saturn at its highest at this time, our local midnight is about 1:30 for summertime here in Ireland. If we take a closer look at Saturn it’s going to be at its brightest and at its closest to us, we can also see several of its moons. At the moment its rings are just barely visible, practically edge on to us. Saturn looks great at around these dates, and we can see its largest moon Titan for all of them as well.

If we come back to the 20th, Titan will pass in front of Saturn. This is a transit and a much better one than the transit of Titan that we saw on the 4th. This transit is even more distinctly a transit, Titan is definitely in front of Saturn. it looks like we can just about catch this transit from here in Ireland if you’re willing to go out at about 6:30 in the morning. This is just before Saturn goes down in the west, which is another aspect of opposition. At opposition, it’s with us all night long from sunset to sunrise, but in order to be visible that entire time, Saturn needs to be just rising as the Sun sets and just setting as the Sun rises. The transit is just getting started, and Saturn will set for us before it finishes. This transit would therefore be a little bit better visible from somewhere else on Earth, a little bit further west. If we get rid of the atmosphere and the ground then we can follow this transit a little bit longer. This lets us see Titan really passing in front of Saturn and off the other side. We can see the shadow of Titan hitting Saturn behind it, as a darker shape next to Titan. This transit will look a little bit better from a little bit further west, if you’re a little bit further west than Ireland, you will get to see the whole transit of Titan going in front of Saturn. This is a rare thing, as I mentioned in a previous video, because of the tilt of Saturn and the angle at which we see it. We do normally see moons like Titan, that are far from Saturn, a little above or a little below Saturn rather than seeing them directly in front. That’s Saturn’s opposition this year, coming up very soon, just at the end of the month.

If we move through time, we’ll see that over the course of a year, Saturn’s position doesn’t change much. We need to move from year to year in order to really see Saturn moving distinctly from the stars. Starting from Saturn’s opposition this year, if we move back to last year keeping the date and time the same, then Saturn would no longer be directly above the south. Saturn will have gotten noticeably further west. To get back to opposition, we’re going to have to change the dates, because Saturn is after moving a little bit in its orbit. Coming back to September 8th, and Saturn is reaching its opposition. Now however, it’s further from us at 8.658 AU, a little bit further from us when it reaches its opposition this year. Saturn is at its brightest at opposition, and last year that was magnitude 0.57. Coming back to 2025, and changing the date again to make sure that we’re seeing it at opposition, and we’re seeing it at 0.58. This year, it’s a little bit closer but a little bit fainter. You would expect the opposite, but the tilt of Saturn’s rings is getting involved, changing the area that’s reflecting light. The distance is changing due to the orbits of the planets. The orbit of the Earth is an ellipse and because of our elliptical orbit there are going to be years where we are further from the Sun and closer to Saturn when it’s at opposition, and there are going to be years when we are closer to the Sun and further from Saturn. Saturn’s orbit is also slightly elliptical, so that will also play into how close it is to us and how bright we see it.

Coming back to opposition in 2024, again we have to go a few days back from the date in 2025. Saturn has, since 2024, moved a little bit around the Sun, so as we go back in time each year, we’re going to have to go back by a few days as well, to get Saturn back to opposition. If we go back another year to 2023, the same thing will happen, Saturn’s not quite at south at the same date, so we have to come back a few days, from the 9th of September to August 28th. That year the Moon was up, passing by Saturn just before opposition and really interfering with the view. However, as with every opposition, Saturn was 100% illuminated, at 8.763 AU which is a little further away again. These changes in date and distance help us tell that we’re lining up with Saturn at different points of its orbit. We’re seeing it brighter again in 2023, up to 0.43. Again, despite the growing distance, the change in the tilt of Saturn’s ring is making it seem brighter. If we keep going through years, these details will keep changing, so we’ll make a big jump, we’ll go all the way back to 2010.

Back in 2010, Saturn’s opposition would have been at a much different time of the year, we’re going to have to come back day by day through the year until we get Saturn up to the south at physical midnight. We won’t be in summer anymore, we’ll be back to UTC+0, meaning that our local physical midnight changes from 1:30 at night to 12:30 at night, or 00:30 if you prefer. We’re back into winter time back in the year 2010, and back to March 21st to get Saturn up to opposition. It’s at 100% illuminated, and down to just 8.504 AU from us, a little closer than opposition this year, and at magnitude 0.51 it’s also a little brighter, as we’d expect. Saturn is again at opposition and it’s a different distance from us again, it’s a different level of brightness again, this time brighter than 2025, still faint than 2023. Again, opposition is happening on a different date, a completely different time of the year as we’ve jumped over a decade. If we take a closer look, Saturn’s rings are visible at a different tilt, we’re seeing the rings at a different angle than what we were seeing them as for this year.

If we move through time and stay locked on Saturn, we’ll see the tilt of the rings change. Even just on year forward to 2011 and Saturn’s at a very different tilt, visibly different each year. Keeping the date the same means that we’re also seeing Saturn further from opposition. Coming back to 2010, Saturn’s shadow is not visible on its rings, because the shadow is directly behind it. it’s directly in line with us and the Sun, so we don’t get to see its shadow. As we move through the years, we start to see more and more of the planets shadow falling on its rings, which helps us to tell that Saturn is getting further from opposition. We could see a lot of Saturn’s shadow in 2016, and its rings were also more visible, an incredible tilt. Continuing forwards, the tilt keeps changing. Once we’re back to 2025, the rings are barely visible.

Jumping year by year means we’ve come to March 21st 2025. This was earlier in the year, when the rings were incredibly thin, practically invisible due to the tilt. Thankfully they have gotten a little more visible over the course of the year. If we keep going year by year, we can see the tilt changing, giving us a better view of the rings as we come into the 2030s, and of course moving further from opposition. March 2025 wasn’t opposition this year because of course opposition this year will be on the 21st of September. However, it did show Saturn’s rings at a very shallow angle. Moving ahead day by day, as we come forward through this year the tilt changes and the rings become more visible again. Most of this change in view is down to the axial tilt of Saturn, similar to the tilt causing the Earths change in seasons. However, how much we see the rings doesn’t just depend on Saturn’s tilt. Both the Earth and Saturn have slightly inclined orbits, though not by much it is enough to change how we see things over time. As we come back to opposition, the illumination percentage goes up as well and the distance numbers come down.

That brings us back to the opposition of Saturn for this year, after a look at opposition for some previous years, just to give you an idea of how much it changes. Our view of Saturn changes drastically, how bright it is, how close it is to us, the tilt and visibility of its rings. It doesn’t just change over the course of the year, but over the course of many years. The date of Saturn’s opposition will change over from year to year and how it looks at opposition, whatever the opposition is. Even if you go and look at Saturn at opposition every single year, the date you’re looking at it will change and how you see Saturn will change. Just before the opposition on the 21st, at 1:30 in the morning here in Ireland, we have that transit of Titan coming up on the 20th. We will just about get to see it, as I said, at about 6:30 in the morning. We will only get to see the first bit before Saturn dives under the horizon. We should get a chance to see Titan’s shadow passing on to Saturn, just as the Sun is rising. So a little tricky for us to see here in Ireland, a little bit easier from other places.

I hope that you get to see Saturn at opposition this year and in future years, I really hope you get to see it in the 2030s when its ring is going to look so much nicer at opposition. If you enjoyed this piece then please do like it and if you enjoy this kind of content, then you can subscribe to this website and my YouTube channel. Thank you very much for reading and hopefully I’ll see you back here next time.