Caoimhín's Content

Today we are going to be looking ahead to the night sky for the coming month of February. There are a couple of interesting things happening in February, the greatest elongation of Mercury on the 19th and an annular solar eclipse on the 12th in particular. However, because the annular solar eclipse is mostly going to be visible from Antarctica, we’ll deal with that at the end of the month. We might mention the greatest elongation of Mercury again at the end of this piece, but we’re going to stick mostly with the early part of the month.

Even at the beginning of the month, already we need to wait a little bit longer for the sky to actually get dark. We’re starting at about 6:45 and the sky has just gotten dark. There will still be a little bit of sunlight glow over in the west, and of course the Moon is at its fullest at the beginning of February. We’re going to have our New Moon roughly on the 17th. Taking a look at the Moon on the 1st of February, and already it’s at 100% full from here in Ireland. The Full Moon is 369,000km away, so it doesn’t really count as a supermoon anymore. We have had a couple of supermoons in a row over the past couple of months. The Moon at its fullest is now a little bit further away from its perigee, its closest position to us. In fact, it’ll be pretty much at a apogee, at its furthest from us, when it is in front of the Sun at the end of the month, that’s why it will be an annular eclipse rather than a total.

Looking at the sky from here in the city with the Full Moon, this is pretty much the worst conditions you could get. We’re looking at the sky with light pollution, with the light of the Full Moon, and there’s still plenty that we can see before 7 o’clock. Sirius is already over the southeastern horizon, Orion is completely up in the sky over in the southeast as well, we can see all of its brighter components. We’ve got a good view of Aldebaran and the Hyades in Taurus, a little higher and further south, as well as the Pleiades. Luckily the Full Moon isn’t too close to them, being over in the East just after sunset, so it’s not going to interfere too much with this region of the sky. Within a couple of days the Moon will be past full, it will be under the horizon when the Sun sets. Still very early in February but through to the 3rd or so, we’ve got a pretty good view of the sky. Just to make sure it’s as dark as possible, we’ll move forward to 7 o’clock. This gives us as good of a view as we’re going to get. Jupiter is still nice and clear, nice and bright over in Gemini, a little bit past its opposition now, it got to opposition in January. Saturn is still up, but way over in the southwest, it’s noticeably much lower in the sky, much closer to sunset in the west, and that’s going to make it that little bit harder to see.

Taking a look right into the south, around the middle of the southern sky, it does look pretty empty, especially as we’re looking at it here in the city. However, this region of the sky contains some famous constellations like Pisces the Fish and Cetus the Great Whale. Higher in the south are the two brightest stars in Aries the Ram, they are just about visible but a lot of the other fainter constellations down in this direction are not. The Square of Pegasus is also clearly over towards the southwest, and in the center of the sky we have not even Andromeda, but more the fin shape of Perseus. It’s definitely a good time to look for Perseus and the very interesting star Algol. Algol, also known as Gorgonea Prima, Gorgona, or the Demon’s Eye. This is the eye of the Gorgon Medusa according to Greek mythology, held in the hand of Perseus. It’s a double star and an eclipsing binary system, which means that the two stars that are orbiting around each other one will line up with the other from our perspective. The two stars will be in line with each other sometimes and separated from each other at others. This makes it appear like a variable star, it looks like it gets brighter and fainter depending on whether or not the stars are in line with each other. That winking effect is one of the reasons it was known as the Eye of the Demon even in other cultures that weren’t associating it with the Gorgon Medusa. Algol comes from Ra’s al-Ghūl, the Head of the Ogre, with “ghūl” being the origin of the English term ghoul. Just east of Perseus we have the nice pentagon of Auriga with the bright star Capella.

I don’t normally look at the sky under worse conditions than Bortle Class 5. I usually discuss the sky assuming roughly the level of light pollution we’d have in Cork City, which is around a Bortle Class 5, pretty close to what would be a suburban sky. Moving up to an actual urban sky, Bortle Class 8 is what would be considered a city sky. This means we lose a lot of the fainter stars. Under these conditions, you won’t see all of the Pentagon of Auriga, nor all of the Fin of Perseus. You won’t see all of the Square of Pegasus, but we’re still seeing the brighter stars. For example, in Gemini, the two Twins Pollux and Castor, are nice and clear. We still have Sirius, the brightest star, in Canis Major, and we have Procyon, the brightest star in Canis Minor, so both of the dogs, the Big Dog and the Little Dog, are visible. The extra light pollution blocks out a bit more of Orion, the belt is a little bit tougher to see, we’re certainly after losing the sword. Thankfully, the brighter stars, Betelgeuse and Rigel, are still very clear and visible. We’ve lost the Hyades and pretty much lost the Pleiades, but we still have Aldebaran. So we’re still catching some of the more obvious constellations, but we’re after losing a lot of those fainter stars.

Turning around to the north under these conditions, and we’re missing parts of the Plough, it’s almost tough to see the Plough at all. The Plough is down to the northeast, but we’re missing enough parts of it that its shape is no longer very obvious. The North Star is still nice and high in the north, you can still follow the Plough up to it. The lines of the constellations in Stellarium do show that it is the Plough, despite the stairs that are missing, and the North Star. Thanks to the time of year, we’re definitely losing the Summer Triangle. Of course, the Summer Triangle is up all night during the summer, but we were still able to see the Summer Triangle as the Sun set over a lot of winter. Now that we’re moving into February, the Summer Triangle will be set by the time the sky gets dark and it will be coming up again as we come through to morning time. Returning to the south with the constellation lines to help us, the empty region of the southern sky is filled in. Low and due south we have the River Eridanus, the river in the sky, it’s another pretty faint constellation. If we bring up the names, initially they come up in English, the translation of what the names we normally use. As such, Perseus is the Hero, Andromeda is the Chained Maiden, Pegasus is the Winged Horse (that one is at least nice and straightforward) and Auriga is the Charioteer. If we change these names back to Latin then we’ll get the names that we normally call them. So in the south we have Eridanus, Cetus the Whale, as I mentioned, Pisces, Perseus, Andromeda, these famous constellations.

Looking a little east of south, to Canis Minor and Canis Major, they’re separated by Monoceros the Unicorn. Even though the unicorn is pretty much impossible to see in the city, we’ve got two bright stars, Sirius and Procyon, just either side of the constellation, so we can still tell where it should be. The part of the sky that I mentioned looking, empty even from a city like Cork, with less light pollution, that’s where the river Eridanus the River and the Great Whale Cetus are, even though without the pictures helping us, they’re pretty much invisible. We’ve only got a couple of bright stars, really one bright star, for Cetus. We will come back to the sky that I am a bit more comfortable with, we’ll go back to Bortle Class 5 for the suburban sky, roughly the level of light pollution we get in a lot of Cork City. At this lower level of light pollution, more stars in Cetus, and a star there in Eridanus, are visible, but a lot of this region of the sky looks pretty empty, those stars are just a little bit fainter. We will push ahead to morning time, just in case there’s anybody who is up early in the morning in February. We’re going to push all the way through and skip a lot of the middle of the night, coming back to just a little bit before sunrise, so we have a few more things actually visible.

We have Scorpius nice and clear above the horizon in the south-southeast, but the Moon is going to be in the morning sky for a the early portion of the month. Coming up to the 17th we’re back to the New Moon so there is no Moon in the sky, but for a lot of the early part of the month, because the Full Moon is at the start of the month, it’s going to be moving through the morning sky as we come through to the middle of the month. Coming to morning time, the Summer Triangle is completely back up in the sky in the morning, above the sunrise to the east. We’ve gone the whole way through the period of the year where we see the Summer Triangle at sunset and it’s come back around to the morning. I already mentioned Scorpius, which means we’ve got the glow of the Milky Way. If we’ve got the Summer Triangle and Antares, the red star in Scorpius, that means the core of the Milky Way is roughly east of Antares and the arm of the Milky Way is stretching out in the direction of the Triangle.

We will quickly hop out to a darker part of the countryside, but we’ll only go to Bortle Class 2. That is equivalent to a good dark site, not as amazing as a true Bortle Class 1, which we do have in some parts of the world. From there we’ve got the glow of the Milky Way stretching across the sky in the morning, at just about 6:15. If we move a little bit later, the glow of the Sun will come in and block out the glow of the Milky Way. Even as late as the 13th still have the Moon ahead of sunrise, even though it would be waning at this time of the month. On the 13th it’s a waning crescent, 25.5 days old, so almost back around to its 29.5 when it comes back in front of the Sun. Now that we’re through to the middle of February, we’ll come back a little bit to just about 6 o’clock in the morning. We can now really follow the from the Ploughs handle, the arc Arcturus and spike down to Spica, the lovely bright blue star, nice and high above the horizon. It’s even past its highest point, past due south by the time we come through to 6 o’clock. A little further west, Leo the Lion is still visible.

For the other zodiacal constellation, we’ve got Libra, but Libra in particular is a tough one to spot. If we bring up the lines of the constellation again, Libra is revealed between Scorpius and Virgo. It’s another constellation where seeing it on its own may be tricky, but we have the bright star Spica in Virgo on one side, we have that bright red star Antares in Scorpius on the other, so between those stars must lie Libra, even if you’re finding it tough to actually see it. We’ve got Corona Borealis up nice and high in the morning as well, just next to Boötes and that bright star, Arcturus. Those are some other constellations that although they might be tough to spot, they’re in good positions to see in the morning as we come into February. Corona Borealis, in the countryside, has a very clear curve, almost a C shape in the sky. If we come back, even just to the light levels we get here in Cork City, a suburban sky, not even a bright suburban sky, things get a lot more difficult. There is one star in Corona Borealis visible, but we’re not really seeing the rest of that C shape. We can just about see a couple of stars in Libra, but nothing to really indicate the shape of the scales.

While we’re here, we will very quickly go through to the 19th and we will come back to sunset. We’re looking at Mercury’s greatest eastern elongation, which means it’s visible in the west. Just as the Sun goes down, there’s Mercury and a little bit of the Moon. We will talk a little bit more about that as we come to the end of the month because we’re also, I believe, just barely getting Venus there as well. We’ll take a look at this lovely sunset view once we’re a little bit closer to the 19th, we have that to look forward to over the course of the month of February.

I hope you get a chance to see the sky at any light level, just to be able to pick out some of these brighter, more obvious constellations over the course of February. I hope you do get the chance to see them, but if you don’t, at least you’ve gotten a preview here. If you enjoyed this piece, 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 watching and hopefully I’ll see you back here next time.