Caoimhín's Content

Today we are going to take a look at some deep sky objects. Deep sky objects are just objects outside of our solar system. In a way, the stars are deep sky objects, but we don’t really think of them as objects generally, they are just stars. Deep sky objects are things like other galaxies, globular clusters and nebulae. Some of them are inside our galaxy, some of them are outside our galaxy, but compared to the Moon, Mars, the asteroid belt, they’re all in deep space, far outside of our solar system.

In the past when looking at deep sky objects, I have looked at a class of deep sky objects at a time. For example, taking a look at just globular clusters, just galaxies or just nebulae. There is certainly a past post on this website whose topic is nebulae generally. This time however, I’m going to look at some of the interesting things that we get to see at this time of the year, the things that are above the horizon and reasonably easy to see. Using the Stellarium software, deep sky objects can be highlighted, and they are highlighted earlier if they’re easier to see. This makes it easy to tell what’s visible based on what’s being highlighted, such as based on our view from inside a city similar to Cork. Even with just a few objects highlighted, already there is definitely a pattern in the sky. There are a lot more objects along the line of the Milky Way than there are outside of the Milky Way. There’s simply more stuff to see when we’re looking into our galaxy.

Rather than jumping out to the countryside, we’ll get rid of the atmosphere, to quickly see if this would hold up under perfect conditions. With no atmosphere, any light from the ground won’t be reflected back or diffused and refracted, eliminating that aspect of light pollution. Even though this reveals a lot more deep sky objects, most are still along the line of our galaxy. There are deep sky objects off of the galactic plane, various globular clusters for example, and of course other galaxies. However, focussing on the brightest and easiest to see, there is definitely more material along the Milky Way, especially down here towards the south, the core from the perspective of the northern hemisphere. Despite the better view from the countryside, we’re going to return to the city view, because I do want to concentrate on things that are reasonably easy to see. Unfortunately, looking at the night sky at the moment, the Moon is in the sky. I don’t want to give a perfect ideal conditions view here because those perfect ideal conditions are so hard to get. It’s much more realistic to take a look at the sky when it’s full of light pollution because that’s what most of us have to deal with. As such, we might as well throw the Moon in there as well, given that the Moon is up for so much of the month. It is at least a little less than full and not directly in front of the Milky Way.

One of the globular clusters that is highlighted off the plane of the Milky Way, even from the city, is the Pegasus cluster. It’s a big and reasonably easy to see object, despite not really being visible to the naked eye. One of the signs that this is something that’s easy to see is that it has a Messier number, this is M15. Charles Messier was working back in the 1700 to 1800s, and so his telescope wasn’t exactly amazing. It was for the time, but not compared to many telescopes today. The Pegasus cluster is just about visible with a big pair of binoculars today. If Charles Messier could see this way back in the 1700s with the kind of telescope he had access to, there’s a good chance you’ll get to see it as well with the kinds of telescopes that we have access to in the modern day. Even using a reasonably small telescope, you should see some dull circular shape. If your telescope is too small, something diffuse like this cluster of stars can be tricky to see. Globular clusters are brighter in the middle, but they get fuzzy around the edges. To see that kind of fuzziness, you do need a reasonable amount of magnification. Using the smallest telescope stellarium will simulate, 6×70, will reveal it with a good eyepiece and an extra Barlow lens. Without those, it’s just barely visible as a fuzzy blob. It’s hard to tell with a smaller telescope that this is different from a distant galaxy or circular nebula. This is a lot closer to us than any other galaxies, but it is also smaller. These globular clusters are around the Milky Way, although globular clusters have been seen around other galaxies as well.

This is the Pegasus cluster, so no surprise that it’s in the constellation of Pegasus. Finding objects like this is one of the reasons why it’s useful to get an idea of how to recognize the constellations. The Pegasus cluster is right on the western edge of Pegasus, so it rises ahead of most of the rest of the constellation. It’s already at a reasonable height at around 1 o’clock in the morning, just after midnight and coming up to physical midnight here in Ireland. We’re not really seeing much of the body of Pegasus itself at this time. We can, however, see the stars that are part of Andromeda. The Andromeda Galaxy is up, just under Cassiopeia. Getting rid of highlighting on the objects, which is of course very useful, we can still find the cluster unassisted. We know that the W shape in the east is Cassiopeia, pointing down to the Andromeda Galaxy, and we know the Andromeda Galaxy is in the constellation of Andromeda. Andromeda shares one of its last stars with the constellation of Pegasus, so we know that a little south of Andromeda, roughly, must be Pegasus. The Pegasus cluster is just above the Head of Pegasus, past the Square of Pegasus. If we bring up the lines of the constellations, it shows that the Square of Pegasus is still quite low, the bottom of it is just coming over the horizon. The head of Pegasus is the star Enif, just under the Summer Triangle, under the constellation Delphinus. Of course, it’s very hard to recognize the Square when one corner is missing. If we go a little bit later in the morning and leave that other star, Algenib, get above the height where the atmosphere is extincting it, then we’ll have a much better view of Pegasus, making the Pegasus globular cluster a little easier to find.

It is tricky to spot where it is in the city, and unlike the Andromeda Galaxy, even if you are in the countryside you are not going to see it with the naked eye. If you’re in the city, you’re going to have to use the of the constellations, and it may help to start with roughly where the Andromeda Galaxy. We can start seeing the Andromeda galaxy with a small pair of binoculars and then go up to something more powerful to take a closer look. With something more distant and more faint, like the Pegasus cluster, it’s going to take a little bit of zooming in before it becomes visible at all. You’re only going to get what could be called a good view with a reasonable telescope, a binoculars isn’t going to do it. For these reasons, it is a slightly more difficult target, but it is a globular cluster that we can see. The Andromeda galaxy, of course, is a galaxy that we can take a closer look at as well.

Down towards to southern horizon is the core of the Milky Way. I often say that if you want to see something in the sky, pointing your telescope roughly into the Milky Way is a good way to do it, simply because there is so much stuff all along the path of our galaxy across the sky. Looking at the center of the galaxy, just a little west of the top of the teapot of Sagittarius, is a productive area to start. You can often spot some nebulae pretty quickly, and often these are star forming regions. The Lagoon Nebula is one of these regions, and that is what I would call this region of the sky. It is also M8, another indication that it is easy to spot. Herschel 36 is the name of the cluster of stars within the nebula. This is a different kind of cluster, not a globular cluster, more likely an open cluster like we see in the Pleiades. just above the Lagoon Nebula is the Trifid Nebula, one of my favourites and another messier object, M20.

I mentioned one drawback to looking around an area with a telescope in in a previous piece. The piece in question is the one where we took a look at the Virgo cluster of galaxies which with our Local Group, the Milky Way, Andromeda and Triangulum, form the Virgo supercluster. I mentioned that pointing your telescope into the sky without really knowing what you’re looking at or what you’re looking for can make it hard to actually find things in the sky. You could be panning around empty space for quite a while before you hit on something, but you are less likely to run into that issue of panning around empty space if you have, first off, a wide field of view, but also if you’re looking into the Milky Way galaxy. Without a very wide field of view, you do need to start by pointing in an area that you know has stuff in it. Pointing a small telescope into the Milky Way should allow you to immediately start to see some nebulosity. If you keep looking around through the telescope, try to roughly follow the Milky Way up the sky. Every now and again it’s a good idea to double check with a smaller scope or your naked eye, and make sure you’re still pointing where you mean to, it’s easy to get lost.

There are plenty of dark nebulae in the Milky Way that may be hard to spot unless they are blocking out a light source behind them. There are also cluster of stars that may not come across as a cluster straight away, it may take a second for them to resolve into a ball of stars, rather than an indistinct smudge. Some larger objects can be used as a marker to find fainter ones. If you spot the Lagoon Nebula, which you may manage to do with just a binoculars at first, the Trifid Nebula will be nearby, just a little further north and a little further to the west. Just by moving through the Milky Way galaxy, as long as you pull back and check your position occasionally, you are likely to see some objects. Continuing northward from the Lagoon Nebula is the Sagittarius Starfield. There are some dark nebulae blocking out light from the Sagittarius star field, giving another interesting thing you can see. Continuing up higher is the Omega Nebula, which does seem to have a bit of a loop shape, maybe a little like the Greek letter omega. Of course, a lot of these names, they don’t match up with the look of the nebula anymore. A lot of these objects were named with far worse telescopes being used, giving far fuzzier views.

All of this so far has been from a city sky with all of the light pollution that brings. This would be even easier if you were out in a countryside sky without any light pollution getting in your way. There would of course be a lot more stars to see, but any faint traces of nebulae will stand out a little bit easier as well. It also easier to see the different brightnesses of stars. Many more of the faint “background” stars are visible, with the occasional brighter stars standing out. Really, a lot of the fainter stars are closer to us than the brighter stars, it’s just down to the brightness of the stars influencing how we see, but that’s something we can maybe take a look at another time.

I hope that you get a chance to see some of these objects yourself, and I hope you enjoyed this piece. I hope you liked this more realistic look at what you can see just pointing your telescope in towards the middle of the Milky Way and some of the deep sky objects that we can see out in that direction. If you did enjoy this piece, then please do like it, if you like this kind of content, then you can subscribe to this website and my YouTube channel to see more. Most importantly, thank you very much for reading and hopefully I’ll see you back here next time.