Caoimhín's Content

As usual, as we draw to the end of one month, this piece is going to be an overview of what we can expect next month. We’re going to look ahead into August. Of course, not much is going to change between late July early August, but over the course of the month we will start to see more and more differences. There’ll also be a few particularly exciting occurrences over the course of the month.

Starting just a little into August, within the first week, and at the beginning of the night as the Sun sets. We’ll also start assuming some light pollution blocking fainter objects. While it’s early, we will still have Scorpius and Sagittarius, but being visible right at sunset and already a little to the West, they won’t be visible for long this month. Even this early in the month, we will already have Saturn above the horizon once the sky gets dark at just 10 o’clock. As we move into August we’re moving out of summertime, and we can see the Summer Triangle almost above the South by the time the Sun sets. That’s an indication that it’s not going to be with us for quite as long, as we’d expect when we’re leaving summer. Pushing forwards past midnight, as early as 1:30 in the morning Jupiter and Mars will be coming above the horizon towards the East. This close to physical midnight, it’s not even morning time, it’s just very late at night, and we already have those planets visible in the sky. Pushing closer to sunrise and we’ll start to see those constellations that are coming up as we get into August. Gemini and Orion for example will be there in the morning. If you had a look at my piece about the planets visible in the sky in the early morning of late July, then you might be able to see that early in the month not too much is different. We haven’t moved that far forward in time, so we are seeing very similar sky.

To see some more changes we’ll need to push forward towards the middle of month. We’ll begin again at sunset, with a little bit of an orange glow in the sky at 9:30. We’ll also stop a little short of the exact middle of the month, on the 13th. By this date the Moon will be up in the evening, and the sky is definitely getting darker earlier. The Summer Triangle is still up at sunset, with Vega above the South at just 9:30. The Moon will still be out of the sky by just 10:40, and the sky will good and dark. With the Moon out of the sky and the glow of sunset gone, these are about the best conditions you can ask for. Saturn will be nice and prominent, a good target for observation even this early. If we take a look towards the Northeast, the W shape of Cassiopeia should be clearly visible. Despite being a bit harder to see from the city, the constellation Perseus will up around Cassiopeia, just a little underneath it. This is a great thing because the 12th into the 13th of August is the night that the Perseid meteor shower will peak. The Perseids are ongoing at the moment, they run from 16th of July to 24th of August. I did have a recent piece about meteor showers, but in July the Perseids weren’t after peaking. They will be peaking in August, so even though they run for this very long span of time, 12th of August is when we’re going to get the highest number of meteors. On the 12th we could have up to 100 meteors crossing the zenith every hour. Stellarium seems to be predicting a zenith hourly rate of 55 for the 13th. Predicting the Zenith Hourly Rate or ZHR of meteor showers is quite hard, but 55 would a good amount, and it will include some stragglers from other meteor showers that are ongoing at lower rates.

If you do want to see the Perseid meteor shower, then of course I’d recommend heading out to the countryside. For that reason, we’re going to remove the light pollution and see how such a sky would look at this time of year. Taking a look at the sky on the 12th at a bit after 10 o’clock, the Moon is already below the horizon and barely sending any glow into the sky. This is a great time to look for faint objects. Most of the objects that I talked about in recent pieces, particularly the ones about using binoculars and looking for other galaxies, are those kinds of faint objects. The glow of the Milky Way will itself start to be visible as early as 10 o’clock as we move into the middle of August. There will be no need to wait too late, because the Sun will already have gone down enough. These earlier sunsets and shorter twilights are another sure sign that we’re leaving summertime. Now that we’re through to mid August, the Pleiades will be up before midnight and a lot easier to see from the countryside. As we pass midnight, Jupiter and Mars will rise above the horizon almost simultaneously, they will be incredibly close together. Jupiter and Mars will be almost right on top of each other, at just 1 o’clock in the morning on the 14th, the night of the 13th. The biggest planet in our solar system, Jupiter, and perhaps the most famous, the red planet Mars. They will be very close together, but they won’t block each other out. If you have a wide enough field of view on your telescope, you might get to vaguely see a couple of Jupiter’s moons and Jupiter along with Mars. Taking a closer look at either planet would likely cause the other to go out of view. This close conjunction of Mars and Jupiter is going to be great, they’re going to look very close together even with the naked eye, reasonably early in the night. Of course, as we approach the end of August we’ll start seeing Jupiter and Mars even closer to midnight. From the countryside you should get a clear view of Orion’s Belt over in the east before the Sun rises, but this will depend on having a clear horizon. If you have any big obstructions in that direction they may block out Orion at it will be quite low in the sky. As it reaches its highest at this point in August, the Sun’s glow will start to block it out. Orion’s Belt will disappear earlier if you’re in the city, and it will start to disappear here the countryside as we come up to 4:30. Even by then, it’s still not particularly high in the sky. The planets, especially Jupiter thanks to being so bright, will stay visible a little longer and get a little higher again before they vanish. Saturn will pas it’s highest point in the South even earlier in the night. By sunrise in mid August, the summer triangle is still just about with visible, all three of it’s corner stars are above the horizon, though Altair is starting to set as the Sun’s glow blocks it out.

Moving later into August, up to the 21st, we’ll stay at morning time for now to note some of the changes. Those constellations, Gemini and Orion, are after getting even higher. Sirius will also be high enough early enough to be clearly visible in the morning. Mars will be after falling behind Jupiter, with Jupiter continuing to cross westward in the sky, while Mars seems to hang back in the East. The Earth hasn’t caught up with Mars in its orbit yet, so it’s not going to behave the way you might expect for most planets. We need to catch up with Mars for it to appear towards the South at midnight, and then move past it for us to see it setting earlier and disappearing behind the Sun. For now, Mars is closer to the far side of the Sun and moving away from us, just a little bit slower than we are moving towards it. By now, we will still have two corners of the summer triangle, Deneb and Vega, but Altair has set, and before all of the stars disappear, before the Sun rises. The summer triangle is definitely indicating that by the end of August, summer is over, something I’m sure a lot of us would agree with. Towards the Southwest, a little west of the summer triangle, the Moon and Saturn should be visible quite close together. This is as Altair vanishes, which is too late in the morning for the Moon and Saturn’s interaction. We’ll have to go out earlier, keeping our eye on the Moon, which will be just a little bit past full at 97%. I’d recommend trying to head out a bit after 3 o’clock in the morning, because at 3:40, Saturn will be completely behind the Moon. Even with a telescope or binoculars it will be totally behind the Moon, not visible at all. This is a full occultation, not just a conjunction, better even than a close conjunction. This full occultation will be visible from Ireland at and a little either side of 3:40 in the morning. The whole sky at this time offers a fantastic view. The Moon will be blocking out Saturn, Jupiter and Mars will be up, along with the Pleiades, the Hyades and Orion , all in the sky together. If anything, this may be a little bit of an improvement over the late July sky.

As we continue to move towards the end of month at this time, the Moon will end up above the ecliptic. Occultations are rare for the same reason eclipses are, the Moon only aligns with the ecliptic twice a month for a short time. This means the Moon will be above Mars and Jupiter, so we won’t get an occultation of them as we come into the very end of August, but the Moon will pass close to them both. At the very end of the month the Moon will be a tiny Crescent Moon, only visible close to sunrise. This will help to keep the sky nice and dark even as we start coming up to sunrise. Just as ahead of the Sun as it rises we’ll see Mercury, popping back up at the end of August. Mercury is technically visible above the sunset as we come to the end of July, but the shallow angle of the ecliptic at sunset in the summer keeps it very low, and the angle is so tight we don’t really get to see it here in Ireland due to the glow of sunlight. As we move towards winter, that angle will get less acute. This gives us an early morning sky with the Crescent Moon, Mercury, Mars, Jupiter, Uranus, Neptune and Saturn, all in the sky at the same time. The only planet missing from the tableau is Venus, although Uranus and Neptune of course won’t be visible to the naked eye. Following the arc of the ecliptic westward, we can see that Altair, the bottom of the summer triangle, is definitely out of the sky. Altair will be setting just about 4:30, certainly before the Sun actually rises.

Now that we’ve had a good look at the morning sky we’ll move back towards sunset. Looking at the early evening sky at the end of August, a whole month in the future, it’s easier to see some differences. The Moon will be practically new at the end of August, so it’s not going to interfere too much. As the sky darkens, we’ll see the Milky Way coming out before we even hit 9 o’clock. Over the course of the summer, the days were long and nights were short, along with long twilight periods. Coming into the end of August, that’s certainly going to change. As the days get shorter, it feel like it’s happening very quickly, like we’re losing daytime and losing brightness quite fast. In just a few months, the nights will be longer than the days again. Saturn will still be up with the glow of sunset, certainly from here the countryside, before the Milky Way even appears, just a little after 8 o’clock. This will happen a little later in the city due to light pollution. From the city, the Milky Way won’t be visible, but brighter objects like Saturn still will be. Bright stars and groups of stars will also be visible, such as Plough or the Big Dipper, which will be practically above the sunset. We also still have Arcturus in Böötes at sunset, though it will set soon enough after the Sun. Scorpius will also be visible in the sky at sunset, barely, and it will be setting quite early. The summer triangle will be high to the South as soon as the sky gets dark. This lets us know where the glow of the Milky Way would be if there wasn’t too much light pollution, but it’s not really going to be visible. As we come up to midnight we can see that the Square of Pegasus is nice and high there above Saturn, which would put the Andromeda Galaxy reasonably high up here as well. Having the Andromeda Galaxy nice an high in the sky while it’s still dark makes for better observations. The higher things are in the sky the easier you can see them through a telescope, they will be less extincted by our atmosphere.

Even a little bit before midnight Mars and Jupiter will be above the horizon. Observing them, especially with a telescope, will be a little harder as you will be looking through more atmosphere. If you’re in the city, there’s also probably going to be buildings in the way, making it quite difficult to observe them this early. Thankfully, it’s still reasonably dark for hours to come so you can wait for Mars and Jupiter to get significantly higher in the sky, before we even need to start worrying about the glow of sunrise. Even if you are in the city, even if you are suffering with the glow of light pollution, those planets are now so far from the sunrise you’re still going to be in with a really good chance of seeing them. You can easily see 3 planets with the naked eye, from the city, at about 2:30 in the morning. Continuing to push forward, towards sunrise, just barely visible, Mercury joins the other planets. With how low it is in the sky, unless you’ve got a clear view it might be difficult to spot, it’s certainly going to disappear lower in the sky from the city than it would from the countryside. If you’re at the coastline to the East or Southeast, or if you’re up on a hill or a tall building, then you’ll have a better view. If you do have a clear view, then there’s 4 planets visible to the naked eye even from the city. Of course, Uranus and Neptune are up there as well, putting 6 planets in the sky all at the same time, plus a lovely Crescent Moon, which of course is till visible from the city as well.

With all this going to be visible during the month of August, I’ll be sure to mention these events again as they get closer. I will almost certainly have a video about the Perseids and maybe another quick look at the occultation of Saturn once we get into August, so if you’d like to catch those you can subscribe to this website or my YouTube channel. With so much coming up this month, I hope you’ll come back to check it out.