Caoimhín's Content

Today, we are going to have a very quick look through the month of July. Some of you may have already seen a quick look at the coming month of July here thanks to the article accompanying the Irish language video I recently posted to my YouTube channel. If you go back a few posts, you will see an article with an attached Irish language video talking about the night sky coming in July. My posts accompanying Irish language videos are in English, and the videos are subtitled in English as well. Even if you are not an Irish language speaker, you can still avail of the information. However, just in case you missed it, I will cover some similar information here, though of course not the exact same.

We’ll start, as we did last time, with Mercury being practically impossible to see at sunset on the 1st of July. We’ve already discussed how Mercury at its greatest elongation, which it’s reaching on the 4th of July, is fainter than Mercury when it’s close to behind the Sun. As it comes around in front of the Sun, it gets harder to see, and even though it is further from the Sun in our sky. Away from the equator, it also gets closer to the horizon, and that also makes a big difference to how visible objects are. If we take a look at Mercury in July, it’s low to the atmosphere, so we’re seeing it through more atmosphere. In late June, when Mercury was almost above the Sun, it was reduced to about 1st magnitude by nearly 12 air masses. As we move forward into July, Mercury kind of loops around and comes down lower in the sky. Just after it’s elongation, it’s reduced to about 3rd magnitude by 19 air masses. We’re looking through many more air masses when we’re looking close to the horizon and that affects the brightness of the object. Even without the atmosphere, at elongation we can see Mercury at magnitude 0.6 or so. If we come back to late June, Mercury goes into negative magnitudes, down to about -0.33, and those negative numbers are brighter. Lower numbers, into negative numbers, means brighter in the sky on the magnitude scale.

Taking a look at Mercury with no atmosphere, there appears to be a cluster of stars just behind Mercury around its elongation. Bring up the object labels to check, and it’s the Beehive Cluster of stars. That is a clear cluster of stars, or it would be if it wasn’t right next to Mercury at sunset. Occasionally, in very dark skies with a telescope or binoculars, you can tell when there are more stars closer together than you may expect just by looking, making some star cluster surprisingly easy to spot. A little higher above the horizon is Mars, which is much more reliable over the course of the month. It stays above the horizon at sunset, but as we get later in the month, Mars does end up very low. Thankfully, we are also moving away from the solstice, so by the very end of July, the sky is getting darker noticeably earlier. It’s much, much darker at 11 o’clock at the end of July. Even though Mars ends up quite low in the sky, because the sky is getting darker earlier, it’s appearing earlier while it’s still a little higher. It may be low, but by the end of the month mars is visible quite close to 10 o’clock. If we move back to early July, it’s not visible at 10 o’clock at all.

That is one sign that we’re moving past the solstice, and this is giving us more night time, although it’s not necessarily going to make us cooler. The summer heat will likely continue through July and into August thanks to the Sun heating up the Earth. When the long summer days heat up the rocks and water that are on the surface of the Earth, they do get hotter and then they have to cool down again. As we come towards winter and the days get shorter, it takes time for the heat to radiate away. The days are going to start getting shorter before the 1st of July, really as of the 22nd of June the days are getting shorter. Despite the shortening days, it’s going to take a while for that excess heat to radiate away into the night sky, so it’s going to take a while for us to cool back down. With sunlight continuing to be longer than half of the 24 hour day in the northern hemisphere, temperatures continue to climb before the days get short enough for them to drop.

We’re going to come around to the morning because there are several planets up in the morning over the course of July, and they’re much easier to see than the planets that are up in the evening. Just before sunrise Venus is up, but also quite low in the sky. It is comparable to how low Mars is, but so much brighter that it’s much more visible. Saturn is also up in the morning, but much higher than the other planets reach. As we move through July Saturn continues rising high into the sky. It rises so far that as we come to the end of July, we’re going to start seeing Saturn earlier and earlier. By late July, Saturn is up before midnight, getting visible at just about 11:30. We’re going to start getting Saturn in the evening as we move through July. Coming back to the morning at the end of the month, and we get Jupiter and Venus coming up together. You may remember from the previous piece that Jupiter, Venus and the brightest star Sirius, are all going to be in the sky together once we get through to August, but not quite while we’re still in July. If we move a little bit earlier in July, Jupiter gets pretty hard to see, it’s barely risen very close to the horizon by the time the sky gets bright enough to block it out. Venus, thanks to its brightness, stays visible for much longer. Venus is just disappearing at a little after 5, at 5:20 from the city. Of course, our view is going to be significantly better from the countryside, as it always is.

We will hop out to the countryside, but it doesn’t seem to make a huge difference late in the morning, when nothing besides Venus is visible anyway. If we come back a little bit closer to night time, Jupiter appears to be a bit brighter and a bit easier to see. It will still be low, but being brighter will help you spot it if your eastern horizon is clear. Pushing later in the morning in the countryside, Venus holds on for just a little bit longer, staying visible till 5:45, so it’s holding on for an extra 20 minutes or so. That is one of the many differences, one of the many improvements, that we get if we head out into the countryside. We can also much more clearly see the Hyades with Venus. As they are low in the sky and close to the glow of sunrise, it’s more difficult to make them out from the city. The Pleiades, of course, look like a nice cluster of stars above Venus, whereas only two or three of the Seven Sisters are often visible from the city.

Moving through the month, the Moon moves through its phases and across the sky. The Moon seems to be with us for the whole night around the middle of the month, meaning the Moon is going to be close enough to full. We can double check what night is our actual Full Moon by looking at how illuminated to Moon is. From Ireland, we’re seeing it at 99.8% full on the 11th. Moving back from early morning on the 11th to the evening of the 10th, it’ll stay at around that 99.8%. Even at physical midnight, the Moon stays very low in the sky at its highest. Even though we are past the solstice, we’re still very much in summertime, so the Sun will still be high during the day, with the Moon and the planets being low at night, or at least low in the middle of the night. As we come up to morning time, Saturn’s position is significantly higher in the south than the Full Moon was when it was in the south. This is because the Earth is turning around to look up at the ecliptic. When we’re facing towards the Sun during the summer, we’re tilted towards the ecliptic, so it looks higher in the sky during the day. As the Earth turns around, we end facing the direction that’s tilting away from the ecliptic, so it ends up looking much lower in the sky.

Looking at the sky around physical midnight, close to 1:30, we can see the summer triangle is still nice and prominent. We are still in the summer so it’s going to be with us all night long. Not only are Scorpius and Sagittarius visible, a lot more of Scorpius and Sagittarius are above the horizon. We’re seeing them closer to sunset rather than the very middle of the night, so this is partly to do with the tilts at which we’re seeing things as well. It was harder to see that bottom part of the Scorpion and the Teapot when we were looking at them a few months ago in springtime, before the summer solstice.

Moving later in the month brings us to the New Moon, and getting the Moon out of the way makes the Milky Way a bit more visible. The Milky Way is one of the fainter things out there, but Uranus and even Neptune are up at this time of the year as well. Once we get around to morning time, we are going to have a lot of planets in the sky all together. In fact, if we get Mercury back in the sky we will have almost all of them. We will get Mercury into the morning once we’re through a little bit later in August. Then we will have almost every planet that is visible, minus Mars, plus the two planets that are invisible to the eye, Uranus and Neptune. We’re still going to have plenty of chances to see some of the planets in July, but we’re only going to get to see a few of them. Jupiter only joins in really, once we’re through to about the middle of the month, and Mercury leaves before even then. We will have to be a bit patient with the planets, and even Mars is going to be a little difficult to see.

Luckily we do have a couple of other things going on, including some meteor showers. Again, I mentioned these in the previous accompaniment to the Irish language video, but I will quickly cover them again here. We’ll move up to the end of the month just to get the same group of meteor showers in the sky them in the sky. I hadn’t noticed the Eta Eridanids were running in July last time, but their radiant does pop up. However, they aren’t peaking until August, and we know that one of the biggest meteor showers, the Perseids, is also coming up in August. Even though its entire range of activity covers from mid-July through to the end of August, its peak is pretty early in August, early to mid August, around the 12th. That’s the only night we’re really going to get close to the hundred meteors and hour or so that we can eventually expect to see. We should be expecting zero from them in July, it’s too early in its run of activity.

The Southern Delta Aquariids are the ones that are going to be peaking right at the end of July, on the 30th. They can get up to 20-25 meteors an hour, but it seems like seeing 10-15 an hour in the sky is more likely because they are a little difficult to observe. We can add to that to the background 10 or so an hour. We get around four or five meteors an hour coming from the antihelion all the time, and another few coming from some other points in the sky. There’s always some meteors falling through the sky, but the rate is usually low. With a background rate of roughly 10, plus another 20 or so coming from the Southern Delta Aquariids, that should be 30 or so meteors an hour in the sky. We can add to this again with the Alpha Capricornids. They will be adding another maybe four or five to the sky. Add to this the two minor showers peaking on the 28th, which might still have a couple of stragglers each. We could be looking at 30-40 meters an hour. If you’ve never seen a meteor, that’s not surprising. The background 10 or so an hour isn’t a lot, you really have to look at the sky for quite a while under good conditions to catch one on a normal night. Going out during these showers will vastly improve your chances, and if you don’t get to see something at the end of July with the Southern Delta Aquariids, we’ve got the Perseids coming up in August, which is a much more reliable shower.

This has been just another quick look at July, going over the things that we covered in the Irish language piece for anyone who didn’t catch it. I hope that you enjoyed this piece, if you did, please do like it. If you enjoy this kind of content, please do subscribe to this website and my YouTube channel, I just hit 500 subscribers recently and I’m eager to continue growing that number. Thank you very much for reading and hopefully I’ll see you back here next time.