Caoimhín's Content

Today, as we come up to the end of May and beginning of June, we are going to review the kinds of things that are visible in the sky, starting by looking forward the 24th of this month and the Full Moon. The Moon can be quite bright, especially when it’s full, and the Irish word for “moon” is “gealach”, coming from the word “geal” meaning bright. Our Moon is the Moon or “an Gealach”. I feel like this makes a fair bit of sense the Moon is bright so it’s named after the word for bright. It’s not the only thing in the sky to be named that way. The Aurorae are known as “gealaí” or “gealán”, also containing that word “geal” for bright. They are also a bright thing in the sky, and even the English word aurora comes from the Latin word for dawn or the Roman goddess of the dawn. The aurorae really can be as bright as the light of the rising Sun, be we get to see them in the middle of the night. There are aurorae up here on our side of the planet, the Aurora Borealis in the North, and down on the other side as well, the Aurora Australis in the South.

We’ll start by taking a closer look at the Moon while it’s full on the 24th. By checking the distance to the Moon, we can see that it’s still pretty close to 400,000 km away from us this month when it’s full. It will be getting closer and closer at its fullest until nearly the end of the year, when we will have our next Supermoon. This month the Moon will be a bit over 380,000 km away, while its closest approach is just about 350,000 km. Both the Full Moon and the aurorae are bright, but where the Moon is a still disc hanging in the sky, the aurorae look like curtains of light falling through the sky and rippling in some unfelt breeze. You can usually only see them quite close to the poles, but some people were lucky enough to see the, much further south recently, certainly from places like Cork City, Dublin and other places around Ireland. Not only were the aurorae visible that far South, they were even visible even from within cities, with all the light pollution that entails. Being that bright, it makes even more sense that part of their name in Irish is the word for bright. Although they are visible even with a fair amount of light pollution, as with all things they will look better and brighter form a less light polluted dark sky. Regardless of light pollution, clouds can also interfere with your view of the auroae, luckily aurorae often last for quite a while, so you are more likely to get a break in the clouds.

You may already know, especially if you are a regular visitor, but here in Ireland we have two Dark Sky Areas, a Park and a Reserve. One is down in Cahersiveen in Kerry on the Iveragh Peninsula, but despite its wonderful levels of darkness, it isn’t usually the best place to spot aurorae. Generally, aurorae are less common and harder to see further South. In Irish, the South of Ireland was often referred to as the top, and this persists with the word “uachtar”, literally the Irish for “cream”. Just like cream rising to the top of a pail of milk, Munster was often referred to as “uachtar na hÉireann”. The North of the country was referred to as “íochtar”, the lower part. We normally think of North as the top, at least here in the northern hemisphere, but this wasn’t always the case before compasses and international maps. There is another Dark Sky Area further up the country, in Mayo. Near to Achill Island, the Nephin or Nefin reserve, named after the mountains that are next to it, stretches through much of the upper part of Mayo. Most commonly, aurorae are only visible from even further up the country, at the coast of Donegal. There, you can sometimes see the aurorae far out over the sea. If you want to look at something that’s happening low to the horizon at sunrise or sunset, it’s better to look out over the ocean, or the sea or another significantly large body of water, to the West or East respectively. This ensures that there won’t be any trees or anything in your way. If you are trying to look at the aurorae that are up over the North Pole, going to a point looking North out over the water will provide the same benefit. The aurorae do occur very high in the atmosphere, but if the aurorae are happening high in the sky next to Greenland or Iceland or a similar location far to the North, they will appear quite low to the horizon when you are looking at it from somewhere further South. I mentioned in the previous video that I did not see the most recent aurorae visible from Cork, and that is still the case, though you can check out the last post to see why I’m hopeful that I’ll get another chance. So far, the only kind of aurora I’ve ever seen, was a red aurora which was visible from Donegal, out over the horizon to the North. At the moment, there has been powerful enough solar storms coming from the Sun, that we are able to see the aurorae from much further South, but normally, the aurora is only visible from the North rather than the South.

Coming back to the night of the Full Moon, once the Moon has risen a little it can be seen to be in Scorpius, the constellation of the Scorpion. This puts the Moon in a position where it will interfere with the Milky Way, our galaxy, it will be harder to see for a couple of days around the Full Moon. Pushing ahead to the end of this month, on the 30th, we can see that a lot easier. Looking at the sky around 2 o’clock in the morning, the Moon has yet to rise, but the Milky Way is already up. We aren’t in the middle of summer yet, so the Milky Way won’t be at it’s best at midnight, but you can see a good portion of it if you are in a place with dark enough skies. The Summer Triangle will be up for almost the entire night now as we come into summer, that’s why it is named the Summer Triangle rather than the Winter Triangle. If you are in a city like Cork City, there will be too much light pollution to see the galaxy, but the Milky Way will stretch through the middle of the Summer Triangle whether you can see it or not. The core of the Milky Way will hit the horizon right next to the big red star Antares in Scorpius. Even if you aren’t able to see it with your eyes, as long as you know where the Milky Way should be then you can point your telescope at it. If you zoom in you should begin be able to see a little bit of the cloudiness, some nebulosity. One small but very sharp nebula next to Deneb is the Crescent Nebula. It looks a lot like a supernova remnant, but rather than being what’s left behind after a star explodes, this is the remains of a red giant that shed its outer layer without exploding. The hot Wolf-Rayet star left behind pushes away the envelope of gas. It’s a rarer, stranger type of object, but it looks very similar to a more common stellar remnant. It’s look nice enough if you are in the city, and if you have a big enough telescope to see it clearly it will probably be capturing enough light to make it seem bright. As always, it’ll be a little better if you are out in the countryside.

With the “correct” amount of light pollution in the sky to simulate the view from Cork City, the Milky Way is invisible to the naked eyes. I, of course, believe that Cork City has the “wrong” amount of light pollution and it should be less, but in order to simulate it accurately I do need to be honest about how much there really is. Even then, once you zoom in a little, you’ll begin to see those nebulae, those clouds in space. Even with binoculars, especially if they are as big as the ones I simulate the use of in the video. One interesting region near the core of the Milky Way, just above Sagittarius, is a place with a lot of stars, a star field known as the Small Sagittarius Star Cloud. Being pretty spread out, it’s a great target for binoculars and low power telescopes. It’s not a cluster of stars, the stars aren’t quite close enough together, but you can see it with just binoculars. Allowing our view to drift down the path of the Milky Way will bring us to one of my favourite nebulas, the Trifid Nebula. A blue and red shape broken up into three parts by dark streams of gas, it too is visible with binoculars, though it may appear quite small. If you are in a city like Cork its colours will appear a little washed out. From out in the countryside, the colours are pretty fantastic, vivid and contrasting in a very small area. Even with a fairly small telescope, if you have the right lenses and you’re out in the countryside, this is the kind of thing that you can see by about 2 o’clock in the morning. The simulated telescope is a 60×1000, so about 60mm wide, typical of a beginners refracting telescope, with a 3x Barlow lens to increase the magnification.

2 o’clock is pretty late at night, or early in the morning depending on your perspective, but I think it’s worth staying up or getting up to see something like the Trifid Nebula. I will talk a little bit more about this once we are a bit closer to midsummer, when these things will be up above the horizon even earlier. If you want to make sure that you don’t miss those upcoming posts, you can subscribe to both this website and my YouTube channel, I post videos twice a week, with videos like this, in Irish with English subtitles, at least every month, sometimes even more frequently than that. I hope you enjoyed this description and the video if you watched it, and I hope you’ll come back for the next one.