Caoimhín's Content

Today, we are going to take a look at the late April night sky. We’re going to look at the general features of the night sky, the planets, the stars, the constellations and how they look now that we’re coming into the later part of April.

Speaking of coming into April, we are in “summer time”. Beginning with the Sun at its highest in the middle of the day, right now that means almost 1:30 rather than 12:30 or even than 12. I have addressed in the past how Ireland is a little to the west of the center of our time zone. In the center of our time zone, the Sun is directly above the south in the middle of the day, at 12 o’clock. However, either side of the middle of the time zone, there is a little bit of a drift between the official midday and the physical local midday. This means our local midday is already about half an hour late, 12:30 rather than 12. In Stellarium, putting the mouse over the time brings up some details, this time including a +1. That is summer time I am talking about, also known as daylight savings. In many regions, time is adjusted by an hour depending on the half of the year, normal for winter and an hour ahead for summer. If you are a regular reader then you may have noticed these posts coming out later than normal, and this is why, I’m posting them from the same place, but a different time zone. If you haven’t noticed, then there’s a good chance that your time zone has changed as well, you might be in an area that does daylight savings time as Ireland currently does.

That’s when the Sun will be in the middle of the sky for this coming weekend at least, about 1:30. We’re going to push on towards evening time and turn around to the west as the sky gets into twilight. A lot of the things that have been major features in the sky recently are bow over in the west. High above the southwest we’ve got Mars, and below it is Sirius in Canis Major and between them is Procyon in Canis Minor. A little further west we’ve got Orion with Betelgeuse, already starting to go out of view. Much of Orion is only visible really while there is an orange yellow glow of the Sun in the sky, at least here in Ireland. Almost due west and already low in the sky is Taurus, with the Hyades and the Pleiades about parallel to the horizon. Aldebaran is clear even in twilight and Jupiter is even brighter just up a little bit higher in the sky. All of this is now very much over in the west, with Cassiopeia over there as well a little north of west. Coming around to the south, the Sickle of Leo is already high in the south as the Sun is going down. By the time the sky actually gets dark, we’ve already lost the end of Orion, Rigel is under the horizon at least. With a clear horizon, we can still see those same features in the sky, but take Sirius for example. If you are in a city or in a place of uneven terrain, it would already be behind a hill or a building. The same is true for Taurus and everything in it. The body of Leo is now definitely right above the south. Virgo is also pretty much all above the horizon. Virgo is a bit of an abstractly shaped constellation, but there is nice little rhyme to help you find it. For that, we’ll come up to the Plough or the Big Dipper, which is really high in the sky, almost at the zenith even early in the evening, it will come even higher as we come a closer to midnight. The Plough and the rest of Ursa Major are right above Leo. The tail of the Plough, that tail arc of Ursa Major, you follow the arc to Arcturus and then spike on to Spica. That’s how to find Virgo, arc to Arcturus and spike on to Spica.

Spica is the blue star, low-ish to the south East early in the night and not quite as bright as Arcturus, but visible in the city. I say Spica to rhyme with spike because it is a spike of corn or an ear of corn, while other people pronounce it to rhyme with speak instead. The corn that Virgo carries is wheat rather than maize, as Virgo is from classical mythology, long before maize and other South American produce came to Europe. Once you find Spica, the rest of Virgo is around it, but it is a bit of an abstract shape in the sky, it’s hard to imagine that that’s supposed to be the shape of a young woman. Leo the Lion, Gemini, the Twins, even Ursa Major the Great Bear to an extent, they all look a lot closer to the constellation that they are meant to be. Or, they at least would look like the right picture if we could see the lines. Those lines would make some of the other big constellations more obvious as well, Corvus for example just under the head end of Virgo. There are several constellations that just look like lines. High in the sky, just under the tail of the Plough, the two star line there is Canis Venatici, the pair hunting dogs chasing the Bear. The two star line just under Leo is Sextans the sextant. There are even more examples in other parts of the sky. The lines in the sky can be very detached from the picture they are supposed to draw, and staying familiar with these constellations that are down in the south is a little bit harder, as they change in a yearly cycle. Everything that we see back in the north we get to see all of the time. Those ones are always going to be there, the circumpolar constellations. Even then, fainter ones, less famous ones, like the Lynx for example, they are a little bit more obscure, they get talked about less, and so they’re a little bit harder to remember as well.

Pushing through to the middle of the night, the top of the summer triangle, is already up. Vega is clearly visible in Lyra, with Deneb above the horizon, but low in the sky. Late enough that even the western horizon is hitting true darkness, fainter stars are now getting visible. Just next to Cassiopeia is the fin shape of Perseus. That fin shape of Perseus, is a bit faint, so the sky needs to be truly dark to see it in the city. Under a dark sky with many more stars of a similar brightness visible, it can be a little bit harder to see that shape, as the faint stars don’t stand out that much. Very bright stars and very bright shapes like the Plough or the Big Dipper, they’re going to stand out a little bit better, even in a dark sky. In fact, the Plough or the Big Dipper stands better than the other stars in Ursa Major, and from the city, the head of Ursa Major is very faint, though the limbs aren’t too bad, they’re pretty visible. Spica is now even higher in the sky, but the rest of the shape of Virgo is still a bit trickier to spot.

Continuing to push later, just up to midnight, the midnight sky is already even more significantly different. In the west all of Orion is gone, all of Canis Major is gone, and the Hyades and the Pleiades are gone as well. Jupiter is almost gone, depending on the horizon. Mars is still in the sky as is Gemini, but they are much lower in the sky. Turning around towards the east, and we’ve got a much better chunk of the summer triangle up, not only Vega and Deneb, but the middle of the Swan, with the wings of Cygnus just visible coming out of the side. Altair wouldn’t be far under the horizon from here, but this is still just midnight. Corvus is now directly above the south, but it would be pretty low to the horizon, so that kind of diamond shape might be obscured by trees or buildings. If you are lucky enough to have some clear viewing to the south, then Corvus should be visible just at midnight, even from the city.

Pushing past midnight will put Mars and Gemini out of the sky as well. They were already over in the southwest by the time the Sun was going down, so even though we are into summertime and the Sun will be rising earlier and earlier, Gemini and Mars are comfortably out of the sky while the sky is still completely dark. Around 3:30 in the morning, we’ve now got the front of Scorpius just coming up to due south low in the sky. By now, all of the summer triangle is up, Altair has joined Vega and Deneb in the sky, so the whole summer triangle is up. This means that the glow of the Milky Way is arcing along the sky, on a path from Cassiopeia, through the summer triangle and down through Scorpius just past Antares. Sagittarius would be just down in the south east, mostly still a little under the horizon. The top is just coming over the horizon, but it is really tricky to see. Taking a closer look, you can just about see the top of the shape of the teapot peeking above the horizon. From a little further back, with the atmospheric extinction and light pollution, it’s very faint so it’s going to be quite tricky to spot.

Moving even closer to sunrise will leave things come up a little bit higher. As the glow of sunrise comes into the sky, so do Venus and the Moon, for the morning of the 21st of April at least. We’ve still got Antares and the summer triangle is now up nice and high. A lot of the constellations that are around the Sun are going to get obscured to various degrees. For example, Pegasus, which is up just ahead of sunrise. The whole square of Pegasus there isn’t really visible, just the top three stars, more the corner of Pegasus, making it tricky to recognise. I certainly wouldn’t recognize it straight away, but of course that’s where Pegasus is in the sky. It’s just next to Andromeda, and Cassiopeia has been visible all night. One point of Cassiopeia, points to the Andromeda Galaxy and it is in the constellation Andromeda. Just below must be Triangulum, even though none of it is visible through the glow of the Sun. With those stars missing, because it’s so bright over in the east in the morning, Pegasus doesn’t look itself, it didn’t stand out to me immediately, but it is out there. Lower in the east, we’ve got Capricornus with the Moon, then Aquarius and Pisces, but those are fainter constellations with less distinct shapes. With the glow of the Sun now coming up obscuring them, they are pretty much invisible.

A lot of really famous constellations are visible at the moment. We’re getting to see Scorpius and the summer triangle in the morning, earlier in the evening we’ve got Gemini, Orion and Taurus, and all through the night there’s Leo, Virgo, and the northern constellations as always. All of those bright constellations stand out fairly well, but if you do know the shapes, maybe if you know them better than I do, you’ll be able to pick out some of the fainter constellations. Pegasus might just be visible, along with shapes like Sagittarius. Continuing to push forward, Venus is the last thing to leave the sky. It’s still there at 6:10, but barely. 6 o’clock is often the time that we consider to be sunrise, but of course, that changes quite a lot with the seasons here in Ireland. Venus will fade out by about 6:30, and it would be very difficult to see even at 6:15 from a city like Cork. With no atmosphere to spread out the light of the Sun, even more planets are visible. Just under Venus is Mercury, Neptune and Saturn, and up above the Sun is C/2025 F2 (SWAN). This calls back to a a few recent posts. C/2025 F2 (SWAN) from the previous piece, and these planets visible at sunrise from a few weeks ago. These planets may be visible at sunrise if you are closer to the equator, even from here they are definitely above the horizon, but definitely not visible at least from the city here in Cork.

All of that is visible just in one night, even from a city that’s what you can see in late April. Of course, the Lyrids are coming up as well, I may mention them again next week. If you’re not looking for particular meteor showers, if you’re not looking for a particular comet, this is where the constellations and the planets that are visible are going to be. I hope that you enjoyed this piece, if you did then please do like it. You can also subscribe to this website and my YouTube channel if you’d like to see more content like this. Thank you very much for reading and hopefully I’ll see you back here next time.