Today, now that we are most of the way through October, we are going to take a look at the constellations and see how they have changed since the last time we took a look back in September.
We’ll wait until the sky actually gets dark on the 22nd. We’re quite close to the Full Moon, the Moon is going to be full on the 26th, it’s 86% full here. This is going to block out some of the fainter stars and there is still a little bit of a glow around the horizon. We’re still quite early and it is already fairly dark, but with the Moon in the sky, that is going to obscure a lot of the fainter stars. Luckily, the brighter objects are still clearly visible, and we have the Summer Triangle nice and high roughly in the south, it is still with us, but only for the beginning of the night. Sagittarius is pretty much disappearing under the horizon to the southwest, while the below-Serpens part of Ophiuchus is also quite low over to the west. Knowing this, the core of the Milky Way must already be down, with just the outer arm of the Milky Way visible, stretching through the Summer Triangle, down through Cassiopeia and out the other side.
We are seeing different constellations early in the evening, we have the square of Pegasus now nice and high just east of due south as the sky gets truly dark, at just a little bit after 8 o’clock. We’re already quite close to the end of October, we’re quite close to Halloween, so we are going to be closer to midwinter than the September equinox, the autumnal equinox. This why we’re starting to get these really wintertime constellations back in the sky and we’re seeing them nice and early. Just a bit further east is Perseus, visible as a kind of fin shape. Between Perseus and Pegasus is Andromeda. We’ll keep moving later, up to 11 o’clock. That brings up Taurus and the Pleiades, along with Capella in Auriga, nice and high in the sky already. Lower in the east is the very start of Orion, at just 11 o’clock. If we move forward to the night of the Full Moon,it’s quite bright and it makes a big difference to how bright the sky appears.
If we keep moving forward to the end of the month, we’ll get actual darkness. Moving just into November, the clocks have changed, we’ve gone out of summertime and into wintertime, so now it is just 10 o’clock rather than 11, we’re using UTC instead of the summer UTC +1. Now we have most of Orion, Orion’s Belt in the center, with Betelgeuse up above and Rigel just over the horizon already. These things are going to be changing fairly quickly. We’ll come back to the night of Halloween and move back towards the sunset, because at least the Moon won’t be in the sky as the Sun as going down. Just over in the west, we’re losing Boötes. Arcturus, the brightest star in Boötes is just above the sunset. We can still arc from the handle of the Plough to Arcturus, but it is going to be setting with the Sun in just a week or two’s time. Scorpius already gone at sunset and Ophiuchus is barely visible from the snake down. Those constellations are definitely changing, but higher in the sky we still have the summer triangle for another while.
Even with a view from a city sky, without the Moon, Stellarium is indicating a little bit of the Milky Way, but of course this wouldn’t actually be visible in a light polluted city sky. We will move out to a countryside sky, we will get rid of the light pollution, and that brings the arm of the Milky Way into view, even a little bit of the core of the Milky Way low to the southwest, but this is very early. This is just after the sky gets dark at around 6:45. We will push forward until the sky really gets dark and it gets a bit closer to nighttime. At a little after 7:30, it’s certainly dark by that time here in Ireland, but we’re losing more and more of the core of the Milky Way, only the outer limb remains visible. With all of these extra stars in the sky, the Pleiades are a lot more obvious, we’re really seeing seven of the Seven Sisters. Most of the constellations look a little bit better when you can actually see them, which Stellarium can assist with. This confirms that it is Sagittarius we’re losing down in the southwest just after sunset, and the Serpens part of Ophiuchus is definitely setting at that time by the end of the month, however the upper part of Ophiuchus is still there. We’re after losing Arcturus in Boötes and the rest of it will soon follow. We still have Corona Borealis and Hercules higher over the west.
The constellations split our Summer Triangle, Deneb, Vega, and Altair, into three different constellations. Vega is in Lyra, Deneb in Cygnus and Altair in Aquila. Three different constellations, but one asterism, the Summer Triangle. The constellation drawing show that the square of Pegasus really is in Pegasus and Andromeda is there, just between Perseus and Pegasus, just under Cassiopeia. Andromeda is just a couple of stars in a row, and it doesn’t look that much like a particular shape to the naked eye, certainly it doesn’t look too much like a Greek myth. However, once you know that Perseus is a kind of fin shape, which is a bit easier to see, and Pegasus is the square shape, which is fairly recognizable, we know that Andromeda has to be in between. It’s very similar to how we know, if Sagittarius is setting over in the southwest, then Capricornus and Aquarius have to come next, arcing up towards due south. The Pleiades are especially obvious in a dark sky and we know they are in Taurus, so Aries must be just next to them, a little to the east. These kinds of patterns work for other groups of constellations in the sky as well, because of course there are many constellations that are faint and difficult to see.
As we move towards morning time, the Moon comes up, and we are only moving towards morning time, we’re still only coming up to 10 o’clock, we’ll leave it come up to 11 o’clock on the 30th of October. This puts Orion completely above the horizon, one of the more recognizable constellations, so easier to see anyway, but already getting up early enough to observe. Orion’s really been a morning time constellation for the past several months. Still just at 11 o’clock, the Summer Triangle is already starting to set. Aquila is already partly under the horizon and Altair will be under the horizon just about the time that we come past midnight. That is our sign really that we’ve left summer. The Summer Triangle is still up for some time outside of summer, but it’s only up for the whole night during summer.
Coming back towards morning time, of course, we have the planets Jupiter and Mars, indicating where Cancer and Leo should be, rising in the east. More to the southeast we have Canis Major and Sirius, the brightest star in the sky, also coming up in the morning. With the glow of the Moon, the real outer arm of the Milky Way is harder to see and that’s all that we’re left with coming up to 3 o’clock in the morning. Early in the evening, when the Sun is going down, that’s the time to go looking for the Milky Way at this time of year. We’ve got a very clear view of Leo as we come up to morning time, Leo is now getting nice and high in the sky. Leo was pretty much behind the Sun in July and August, so now it’s coming out from behind the Sun. Before sunrise, Arcturus pops up in the east, so we can still use the arc of the Plough to arc to Arcturus in the morning. The Sun will rise before we get enough of Virgo to spike on to Spica. We’re getting a little bit of Venus in the morning, but still very close to the Sun, still a tricky one to see. That will get easier as we get later in the year.
Those are a few of the most famous constellations, the more recognizable ones, and where they’re going to be over the course of the next couple of weeks, of course it takes a while for the constellations to noticeably change. Losing the summer triangle is going to continue to happen earlier and earlier, but a lot of the constellations that we’re now starting to see in the early evening, like Taurus and Orion, they’re going to be the prominent constellations as we get further into winter itself, as we get into November and December. Quickly turning around to the north and we will get rid of the wonderful dark sky, which is to say we will put back in the light pollution so that we are looking at a more reasonable sky, a sky that more people will see. We’ll go with a suburban sky, the brightest urban skies are only the largest urban centers, so more people live under a sort of medium amount of light pollution, which is of course still a pity.
In the north we have the Plough or the Big Dipper, which is quite low now and it’s going to be low through the night for winter, coming back up in the morning time. It points towards Arcturus in the west in the evening and it will still be pointing towards Arcturus in the morning to the east. We can follow the Plough up to the North Star and out to Cassiopeia. If we move a little bit later, we’re looking at the very early evening here, for many parts of the world it won’t actually be dark until closer to 8 o’clock, we’re getting the darkness nice and early here in Ireland. Once we’re a little later, we can follow the Plough, pretty much from the bottom of the sky, pretty much due north, up through the North Star and then up to Cassiopeia really high, pretty much above the North Star. We can see a little bit of Ursa Minor’s other stars as well, west of the North Star, and then Draco would be just outside them, which of course we know from the Draconid meteor shower that just occurred in October. Over to the east of the north star, pretty much invisible to us, we’ve got Lynx and Camelopardalis. They are over there, but especially from the city they’re pretty much invisible. Again we can use similar tricks, we know Andromeda is between Pegasus and Perseus. Camelopardalis is between Perseus and the North Star, it’s in there, we just can’t really see it from the city.
That should finish up this overview of how the constellations are during October. The fact that we’re getting them earlier, constellations like Orion and Taurus are now becoming evening time constellations instead of morning time constellations, that’s the change that’s going to continue as we move further into winter. I hope you enjoyed this description of the constellations here, if you did enjoy this piece then please do like it. If you like this kind of content, then please subscribe to this website and my YouTube channel. Thank you very much for reading and hopefully I’ll see you back here next time.
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