Caoimhín's Content

Today we are going to take a look at the night sky for June. Last time we looked ahead to the month of June to take a look at Venus and Jupiter having a close conjunction at sunset. Mercury was also up when Venus and Jupiter were up. Even in early June, we have to push almost to 10 o’clock before Venus emerges into the sky, all alone as the brightest object. It is after 10 o’clock by the time Jupiter joins in. On the 2nd of June, Mercury is very close to the sunset, that’s going to make it very difficult to observe. As we move forward in the month, Mercury does get further from the Sun, but the sunset is also getting later, so that means Mercury will continue to be fairly difficult to see even when it comes up to its greatest elongation around the 11th.

Of course, with trees and buildings in the way, it’s going to be even harder to view. If we were looking out across a flat horizon, we would have a much better view of Mercury. However, even when Mercury is at its greatest elongation, before it turns back around and starts moving in towards the Sun again, it’s quite faint until the sky is quite dark. By the time the sky is quite dark, Mercury is quite low and it’s getting extincted by the atmosphere. We will move forward to morning time because we’ve been able to see Saturn in the morning sky since May and it will be joined by Mars. Mars is just about visible as we move later in the month, and of course by the end of the month we’ve moved past the solstice, which means the sky will start getting darker in the morning instead of brighter. Even on the morning of the solstice, the shortest day of the year, Mars is visible as the Sun starts to rise, and we’ve got a fair bit of sunrise glow even at just 3:40 in the morning,

With a view based in Ireland, we are far enough north that a little bit of sunlight glow stays visible in the northern horizon all night long. That means that even in a countryside sky we’re not going to get perfect darkness. If we were in a perfect dark sky park with no light pollution, there would be a significant influence from the glow of the Sun even at our physical midnight , which is at just about 1:20 thanks to the extra hour for summer time that we use here in Ireland. In a perfect dark sky, you’d still get to see the glow of the Milky Way.

With the core of the Milky Way rising straight out of the south at our local midnight, this is technically one of the best times to see the glow of our galaxy. It will be in the same part of our sky at the same time that we would see the Full Moon. Given that the ecliptic is very high during the day in the summer, it’s quite low during the night in the summer, but we’re still seeing all of Sagittarius and all of Scorpius with a perfectly flat horizon. If we bring back a more normal hilled and treed horizon, we’ll lose a little bit. A little bit of the bottom gets blocked out, particularly the tail of Scorpius. We’re still really seeing most of Sagittarius which is a tricky constellation to spot. We will come back in toward a city sky, adjusted to be more realistic view of our sku in Cork City, about Bortle Class 6. The Summer Triangle is still clearly visible, it is made of very bright stars. Antares is still visible and maybe a little bit more of Scorpius, along with the snake like shape of Serpens being carried by Ophiuchus, but we’re really only seeing one star in Sagittarius, so of course it isn’t an ideal view.

If we move forward to the night of the Full Moon, starting on the 29th, though the Moon will technically reach its fullest after we cross into the 30th. We’re not going to be able to see it perfectly full from here in Ireland at any rate, just about 99.8%. The night of the Full Moon is very close to the night of the solstice, which means the Moon will be low in the sky. At midnight the Full Moon is really close to the horizon, very different from how we would see the Full Moon in wintertime. Normally when we get close to the solstice, and I will talk more about the solstice in a few days, I show how much higher the Sun has gotten from its low point in winter to the high point in summer. However, if we jump through the months and come back to a wintertime Full Moon, it will be much higher in the sky. The Moon does a very similar thing to the Sun, but at opposite times of the year. The Moon’s passage across the sky gets lower and lower from winter to summer, and that is all down to the difference in the height of the ecliptic.

The Moon is at its lowest on the 30th, as it is closer to the solstice than the 31st of May, which is our Blue Moon coming up very soon. there is a difference, but it is more subtle. There’s not a huge difference from one month to the next, but over the course of 12 months there is a very observable difference. This isn’t wholly a bad thing. The Moon being lower in the sky does mean that it is more likely to be blocked by buildings and trees, but thanks to an optical illusion created by the way that the human brain processes distance relative to the horizon, the Moon looks bigger when it’s lower to the ground. It’s totally an optical illusion, the Moon isn’t bigger, the way a supermoon is closer to us and looks bigger because it is closer to us, it’s not like that, it’s not a real difference. The Moon simply appears larger when it’s lower in the sky, so that’s going to make the Full Moon look even better during the very, very short night that we get in summertime.

We’ll come forward a little bit more into June. The Moon will be new on the 15th. Of course, if it is full just before the start of the month and full again at the end of the month, the middle of the month is when it’s going to be new. This is still a few days before the solstice, which means we’ll have pretty good conditions. Not the best conditions, of course, because we are still going to have a glow from the Sun late into the evening, but without the Moon in the sky and without the maximal extra light from the Sun that we can get when we are on the solstice, it’s going to be fairly good viewing conditions. There’s still a good bit of light back there towards the north as we come our actual local midnight. The Plough is missing one of its stars, as is Cassiopeia, and the Pole Star is still visible. They are going to be a little bit trickier to observe because you are looking in the direction of that extra light.

As we move forward to midnight, even in the city, we still have Scorpius and a trace of Sagittarius. Of course we’re going to have to wait so late for the sky to get dark and the sky will start to get bright again so early, we’re really not getting to see that many constellations, we’re not getting to see as much of the night sky as we normally do. We are starting to get Pegasus just above Saturn. The Andromeda galaxy would be back north just a little bit in the constellation of Andromeda. Unfortunately it’s right around the north where we’re getting that extra glow, so it’s not the best time to see Andromeda. Despite the extra light of the Sun, if you are in the countryside it is still a good time of the year to see the glow of the Milky Way. Coming back to just about sunset, Virgo is already pretty far across the sky and Leo is barely up for any of the night. By the time the sky gets as close to dark as we’re going to get it, Leo is already starting to set, so those constellations are certainly moving out of view. Instead we’ve got our midsummer constellations of Scorpius and the Summer Triangle, for example, they’re up more prominently now.

I hope you get to see the night sky on the solstice and I hope you get to see the upcoming Full Moons, the Blue Moon on the 31st of May and then the next Full Moon on the 30th or 29th of June. If you enjoyed this piece, then please do like it and if you like this kind of content, 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.