Caoimhín's Content

Happy Halloween! Today we are going to take a look at some of the spooky things in the sky. For this piece, we won’t worry too much about when or where these objects are visible. However, many are visible at this time of the year from Ireland, but many will only be visible with good telescopes from dark skies, particularly some of the nebulae. There are also a few upcoming and ongoing meteor showers. I mentioned the Leonids in the last piece and there will no doubt be another covering them later in November.

The first spooky object is visible on Halloween itself. Waiting till late at night in the countryside, you should see the glow of the Milky Way. As I mentioned in the most recent Irish language video and attached piece, the night sky on Halloween is going to look particularly nice if you’re in the countryside at the right time of night this Halloween. We’ve got a wonderful view coming up, with Mars, Jupiter and Saturn visible. Uranus and Neptune are out there if you’ve you got a telescope. By about 2 o’clock in morning Orion will be coming up to its highest point in the sky, and still in complete darkness. One of my favourite spooky objects in the sky is right there in Orion. Taking a close look at the bottom right and here we have the Witch Head Nebula. If you can get a good view of it, it almost looks like the side profile of a witch. The Witch Head nebula it is a faint nebula and it’s so close to the more famous Orion Nebula here, just off the side of Rigel, that it often gets overlooked. You do need a pretty good telescope and a reasonably dark sky to see it, but just the fact that it’s the Witch’s Head, I think that makes it a good enough target for Halloween. There’s a few other objects out that direction as well, including a couple of galaxies. Those would also be nice targets of observation, but you would need a much more powerful telescope to see those than you would to see this particular nebula.

Nebulae in particular some of the most varied looking objects in the sky, they can look like all sorts of things if you use an imagination. Stars in general look like bright dots. Galaxies are often either lenticular or elliptical, spiral or disc-like, or irregular, and even irregular galaxies normally just look like bright blobs. Nebulae however, because of the different contrasting colours and different levels of brightness in different parts of the nebulae, they can look like all sorts of crazy things. This leads to all sorts of crazy names, some of which could be considered accurate. An obviously spooky candidate is the Skull Nebula. It is also called the Soap Bubble Nebula and the Voodoo Mask Nebula A skull and a mask of a human figure of course aren’t going to look too different. At first glance it doesn’t look too much like a skull, but giving it time for the Earth to rotate a little bit will make it appear to turn. You may need to look at this from a completely different part of the Earth then Ireland to get it to look the right way up. However, if you tilt your head just a little bit, it does look a little like some sort of face, with eyes, a nose and a mouth. The Skull Nebula sounds great for Halloween, but the Soup Bubble Nebula is a fair option, I can see why someone would call this a soap bubble. It does take a little bit of imagination to see it as a mask or a skull of any sort, but that is often the case for any nebula in space.

Clusters of stars can often have spooky names as well. One of the spookiest names is the Screaming Skull Cluster. I certainly don’t see it as a screaming skull but it is a wonderful open cluster. it’s a particularly interesting one. Open clusters are often quite “open”, with lots of space between the stars as in the Pleiades. This cluster has many stars packed seemingly close together, almost like a globular cluster. Taking a closer look, there are a lot of young blue stars in this cluster, whereas globular clusters are often older stars. This interesting object is up in the glow of the Milky Way, near Cassiopeia. Caroline’s Rose Cluster is its most popular name and it doesn’t have a Messier Number. It does have an identifier, NGC 7789, so it is in the New General Catalogue and, up in the 7000’s, indicating that this particular cluster of stars is probably a little tricky to see. It is also called the Ghost Cluster, but clusters of stars are clusters of stars. They are just a group of stars all packed in together, it’s really only if you were looking at these through a telescope too weak to resolve the individual dots of the stars that it would look like a kind of fuzzy blurry shape, That could give an indication of a ghost, whereas with the telescopes that we have today, we have the capacity to resolve the individual stars and see it as it really is. The telescope used when this was called the Ghost Cluster, and probably the Screaming Skull Cluster as well, must have been pretty old fashioned. It’s also called Herschel’s Spiral Cluster, these objects often have many names. Being Herschel’s Spiral and Caroline’s Rose Cluster hint that the Caroline could be Caroline Herschel, and indeed she is the discoverer. Caroline Herschel and her brother William Herschel were active in the very early days of telescopic astronomy, in the late 1700 into the early 1800’s. They would have been working with far weaker telescopes, or at least telescopes lacking modern manufacturing techniques.

Getting back to nebulae, the Skull and Crossbones nebula is another with a spooky name and also observable in the Northern Hemisphere, not too far away from Sirius. yet again, I certainly don’t see it as a skull and crossbones, but it is a very nice looking nebula. It has the reddish-pinkish colour indicative of an emission nebula and dark regions of dense gas clouds. It’s a HII region, pronounced “haitch 2” and meaning it is a cloud of ionised hydrogen. This is a region of space that’s capable of forming stars. It is currently getting heated up by the stars that are forming inside it, causing it to emit that reddish glow. However, it doesn’t look like a skull and crossbones, it certainly has a spooky name, and zooming out a little bit it maybe looks like a face with its mouth open if you use your imagination. A lot of imagination would be necessary and this is generally true for a these nebulae in space.

They are really just clouds and of course, you may have played the game of imagining things in clouds yourself when you were younger, but it does take imagination. Clouds are really just formless shapes of water vapour and these nebulae in space are just as formless billowing shapes of gas. One nebula that doesn’t stretch the imagination too far is the Ghost Nebula. Taking a look at this cloud in Cepheus, you might see some of the “ghosts”, like figures their hands raised. It still requires a little bit of imagination to see these things as ghosts, but not as much as seeing a star cluster as a skull. This is a reflection nebula so it’s catching the light form nearby stars. it has a yellowy-brown colour, and a warm colour like that usually means an emission nebula. Sometimes an unexpected colour like this is due to an object being imaged in false colour or with a different mapping of wavlenghts to the image colours than what our eyes would see. For example, if you are looking at an object that is emitting a lot of red or infrared, then it can sometimes be given cooler colours if they are low in temperature. In the case of the Ghost Nebula, it is a dark brownish nebula catching the light of yellow stars, giving this warm, almost dark orange appearance. It is another very nice looking nebula and it does look like it has a bunch of ghosts in it.

Those are all things in the sky that have these spooky names, and if you use your imagination they can have a spooky appearance. However, they are just clouds of gas floating through space, despite the name they’re not really that scary in and of themselves. Betelgeuse, however, could be truly scary at some point in the future, even if you don’t say its name three times. The actual star isn’t too scary, as long as it really is so far away that won’t cause us any damage when it goes supernova. It does seem like Betelgeuse is far enough away we’re almost certainly safe. For the sake of Halloween, if you do want to scare people a little bit you can say that there is a chance that Betelgeuse could damage us when it goes supernova. According to some theories there is a possibility, but it doesn’t seem particularly likely, we are almost certainly fine.

Black holes can also be quite spooky. They can tear us apart and we don’t really understand them. The unknown can be one of the scariest things, a lot of people are afraid of the dark because they don’t know what’s in the dark rather than being afraid of darkness itself. If we take a look in towards the middle of the Milky Way, somewhere in here is Sagittarius A*. Sagittarius A* is usually written with an asterisk, pronounced as “A star”. Sagittarius A* is the black hole in the the center of our Milky Way. It is in there in the center of our galaxy, and it is a huge supermassive black hole. We are luckily completely safe from it, but discussing the kinds of things, that a black hole could do, can certainly be a little bit spooky. A little closer to us there are many smaller black holes. Up towards the summer triangle, which is still visible at this time of year, we’ve got what I believe to be one of the most famous black holes, Cygnus X1, or X1 Cygni. This was the very first black hole to be confirmed as a black hole, after the theory positing their existence was proposed. This black hole in the constellation of the Swan is a stellar mass black hole, rather than a supermassive black hole. All stellar mass black holes are formed from stars significantly larger than our Sun, the smaller black holes are still the mass of stars, but they can be 10-20 times more massive than our Sun. That’s big, but it’s not 20,000 times more massive than our Sun which is the kind of size you can get for the supermassive black holes in the center of galaxies. There are stellar mass black holes just floating around in space, there’s a black hole just out int he constellation Cygnus, close enough that it’s radio sources can be picked up from Earth. There are black holes all around the sky, sometimes a black hole will pass right over your head! Thankfully from light years away, but it can be a little bit of a spooky concept if it’s put correctly.

They are a few of the interesting things you can take a look at on Halloween or really any time of the year. It’s always nice to talk about some spooky things on Halloween so hopefully you do get a chance to see them or talk about them. If not, a lot of those objects are going to be visible at any time of the year. If you enjoyed this short piece please do like it, and if you’d like to see more from me please do subscribe to my website and YouTube channel. I hope you have a Happy Halloween and hopefully I’ll see you back here next time.