Caoimhín's Content

Today we will continue looking at the upcoming December solstice, as it is now just a couple of days away. However, we are also going to look at the solstice from the equator and from the southern hemisphere. Here in the northern hemisphere we are looking at the winter solstice. From Ireland, the Sun is above the south at about 12:30, at the lowest midday height it will reach all year. The Sun will also rise quite late on the solstice, there’s sunlight in the sky by 8:20, though the Sun itself doesn’t actually cross the horizon until a little bit later, almost 9 o’clock. In the evening the Sun will set very early, just a little bit after 4 o’clock and the Sun is out of view. That is the dramatic shortness of the day that we get here in Ireland, but of course it can be even more dramatic in other locations.

We will go first to the edge of the Arctic Circle. From a more northerly location, about 56 degrees north, we’re still outside of the Arctic Circle, but the length of the day will still be a little shorter. The Sun gets across the horizon by about 9 o’ clock still and setting a little bit before 4. If we go all the way up into Iceland, we’re still outside the Arctic Circle at about 61 degrees north. The viewing height I’m using in Stellarium is 10 meters up in the air, which doesn’t usually make too much of a difference. Elevation does make a difference to when things rise or set, a high elevation can make the day a little longer, but 10 meters doesn’t usually make too much difference. In this case, trying to see the Sun just at the horizon or just below it, a few meters can make the difference. From just outside the Arctic Circle, the Sun is over the horizon, but incredibly low. If we were inside the Arctic Circle the Sun would be below the horizon so we’ll have to go a little further north. The Arctic Circle is at about 66 degrees north, but to be sure we will go a little further, up to 71 degrees north. From there, the Sun does not rise above the horizon at all, but it does get brighter at midday. The Sun almost rises, we have a sort of dawn going on for the whole day. Even at midday, despite the glow of the sunlight, it is still dark enough to see Jupiter and Mars, even with some light pollution. That is as bright as it will get from just inside the Arctic Circle, and that’s only from from just inside the Arctic Circle. If we go significantly further north, even in the middle of the day, it is going to be essentially pitch black. This of course getting less extreme as we move further south from Ireland.

Coming down to around 30 or so degrees, we’re still significantly above the Equator. This pretty much the latitude going through the middle of the continental United States, along the bottom of Europe or the top of Africa. Midwinter here like a spring day in Ireland. It could equally be an autumn day here in Ireland, but the lovely blue sky which serves as the default in Stellarium makes me think more of a spring day. Even though the Sun is still at its lowest, it’s still the winter solstice, it’s not that low in the sky compared to further north. It will rise later, but the sky is quite bright by just 7:20, still pretty early. It will set earlier, but the Sun is just starting to hit the horizon by about 4:30, so the day is that little bit longer. If we keep moving down to the equator, the seasonal difference in day length will practically disappear. Coming down closer to 15 degrees north, still not quite at the equator yet, and of course it doesn’t really look like the Sun is that low in the sky at all. Midwinter here is pretty much equivalent to a how high the Sun would get in the sky for a summer’s day here in Ireland. The day and night are also going to be more even. The Sun is coming up before 7 o’clock and not setting until closer to 5:30, significantly later than sunset on the same date from here in Ireland. Venus will very clearly visible when were this close to the equator, it’s nice and high above the Sun at sunset thanks for the angle of the ecliptic.

Going all the way to the equator, and we can see the Sun is definitely not at the zenith. The Sun is definitely not in the middle of the sky in the middle of the day. The Sun will pass directly across the zenith for the equinoxes if you’re at the equator, roughly at least, the tilt of the Earth does effect when the Sun appears directly overhead for a given location. So this is, sort of, the lowest that the Sun will get in the sky but as you can see, it’s still really close to the center of the sky. Really, this is the furthest south the Sun will get if you’re at the equator. For the summer solstice, or the other solstice, the seasonality doesn’t matter too much if you’re right down at the equator, but for one solstice the Sun will reach its furthest south, and for the other it will reach its furthest north. Either way, the Sun will be lower than the zenith for either solstice if you are right at the equator, both low compared to the zenith position. The Sun will be setting at practically 6 o’clock, so a nice and normal day length, and back in the morning it will rise pretty close to 6 o’clock. From 6-to-6, that’s a 12 hour day, a normal length of a day. The 24 hour cycle will stay close to an even 12 hours and 12 hours each split if you’re down at the equator. The day ends up being a little longer thanks to the refraction of sunlight, but we won’t get into that here.

Now of course if you are past the equator, if you are in the southern hemisphere proper, things start to go the other way. Jumping all the way to 30 or so degrees south, we’ll need to turn around to the north here because of course it is in the north we will see the Sun if we’re in the southern hemisphere. The Sun is going to reach it’s highest north at midday because this is the summer solstice. If you are in the southern hemisphere of course it’s the summer solstice, but most of the other things I’ve said in recent videos will still hold true. The Geminid meteor shower should still have looked great, you’d just have a much shorter night in which to enjoy it. The planets will still look great in the evening, but again you just won’t have as much time to enjoy it because the night will be so much shorter. The planets will also be a little lower in the sky, compared to the same latitude in the north, but this isn’t particularly until more extreme latitudes. Given that it is summer, the weather might be a bit more mild and favourable so it might be easier to go out looking for these objects. Just like the north, we have Jupiter, Saturn, Mars, the Moon and Mercury in the morning. Even though this is firmly down in the southern hemisphere, we are only at the latitude of Australia at 30 odd degrees south, rather than 52 degrees south, so not as far south as Ireland is north. That gives Mercury that little bit more clearance off the horizon, it does make it that little bit easier to see. That would be true for less extreme northern latitudes as well, so if you are in the northern hemisphere but not as far north as Ireland then you are going get a much better view of Mercury as well.

Now we’ll go really far south, right down at the southern tip of South America, and the Sun is definitely sort of low in the sky. Again this is comparable to an Irish summer and at 57 degrees south, this is further south than we are north. However it is still comparable, the midsummer day, as long as that day gets, it will get quite long if you’re far enough South just as it is if you’re far enough north for northern summer. The Sun will get quite high in the sky, as high as it can, but not as high in the sky as it would if you were at a little bit less far south, like in a South Africa or Australia. Heading to morning time here just to take a look for Mercury if we can, the angle of the ecliptic will be even steeper because we’re further south than Ireland is north. It seems like the angle is too steep for Mercury to be visible from the southern tip of South America on the winter solstice. Even Mars and Jupiter will be looking very low, of course that is because it’s summer time. Down in the southern hemisphere the Sun is going to be high during the day, but the planets are going to be low at night and for us back here in the Northern Hemisphere, back here in Ireland, of course it is thankfully the opposite. We’ve got the planets very high at night even though the Sun is going to be quite low during the day, especially around midnight. Mars and Jupiter will be really high in the sky for us, so it’s a fantastic time to look at them with a telescope.

I’ve spoken a bit about the solstice over the past couple of articles, talking about how the planets are going to look, but I did want to say again that the southern hemisphere is doing the opposite. The southern hemisphere is getting their summer solstice while we get our winter solstice, but for the vast majority of the features in the sky it’s not going to make too much of a difference. For the vast majority of things, the Geminids meteor shower for example and all of the planets that are visible at the moment, they are still going to be visible from the southern hemisphere.

While we were talking about the southern hemisphere, we will just very quickly look ahead to 2025. We’re only going forward to January, as there is a comet that should be visible in the morning in January. This was mentioned in a comment on a recent video. Comet 2024 G3 ATLAS is the comet in question, and as |I mention a commenter mentioned this in the comment section under a previous video so thank you for that, thank you for bringing this to my attention. We are only early January, on the 8th and early in the morning as well, just before sunrise. It may be difficult, but it seems to be just barely visible in between Mercury and the Sun. It does look pretty faint, it is coming up as magnitude 3 which is not crazy faint, but reduced to 5th magnitude because it’s very low to the horizon with a lot of atmosphere to shine through. I may touch on this again once we get into 2025 but of course given that this is in the southern hemisphere, if something exciting happens that I’ll be able to see from here in Ireland that will take precedence. If you are in the southern hemisphere you do have that to look forward to in January.

I will bring us back to Ireland and I will return to apologizing for the ongoing reiteration of the fact that the winter solstice is coming up. Regardless, I hope you enjoyed this quick reminder, this quick look at where the Sun is in the sky from those other locations around the world and the fact that it is summer just a couple of hours away. Or 13/14 hours on a plane away depending on where you are, it’s summertime somewhere even when we’re in midwinter. I hope you enjoyed this piece and if you did please do like it, and you can subscribe to this website and my YouTube channel if you’d like to see more content from me. Hopefully, I’ll see you back here next time.