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Today we are going to continue looking at the month of September, the month that we’re now in, and we’re going to concentrate a little bit more on the stars and the constellations that we’re going to see, but we are also going to look at Saturn and Neptune.

First off, the constellations. Just as the Sun sets in early September, we’ll say the 3rd, just a bit of Virgo is still up. The bright star Spica however, is likely to be obscured by the landscape. Once we get through to darkness we’re at about 10 o’clock and the summer triangle is up. The constellations decompose it into Cygnus the Swan, Aquila the Eagle and Lyra the Lyre. In the center are Vulpecula and Sagitta, the Little Fox and the Arrow. These constellations, and Delphinus at the eastern edge of course, would be obscured by light pollution. If you’re here in the city, there’s no stars visible for those constellations. Albireo may be visible in the center of the triangle, but it is in Cygnus. It’s not in Vulpecula, but it’s very near Vulpecula, it’s the eye of the Swan. Most of those fainter constellations, they’re still invisible.

A little bit of Sagittarius is still up, but very low and faint. A little bit of Serpens is visible a little higher, and a little bit of Ophiuchus a little higher again. Barely visible above that is Corona Borealis, still out for those of us waiting for the Blaze Star to eventually blaze. Corona Borealis is still up in the sky in the evening along with the almost invisible Hercules and of course Boötes, with Arcturus visible as its brightest star. Those constellations are still up in the evening, but really only in the early evening. We’re going to move forward to just past midnight, just past midnight on the clock, and the Summer triangle is still up. Scorpius has already set and most of Sagittarius has now sunk below the horizon, so that’s the core of the Milky Way setting. As we turn around to the east here, the Moon is after rising with Taurus just past midnight. Taurus is already starting to come up, you might see a little bit of the Pleiades next to the Moon. As we move a little bit later and the atmospheric extinction gets a little bit less of a problem they should get easier to see, but the Moon is still a problem on the 3rd, very close to the Pleiades in the sky. If we take a closer look, once the light of the Moon gets out of the way, then some of the stars in the Pleiades are just about visible. Aldebrand is much easier to see, the start of the Hyades.

Moving later, with Saturn high in the sky, the Square of Pegasus is clear and visible. One star in the Square of Pegasus, the easternmost, joins into the shape of Andromeda. Andromeda, of course, is a pretty tricky constellation to actually see, we’re only catching a couple of stars from the city, but it is between the Square of Pegasus on one side and the W of Cassiopeia just above. Most of Cassiopeia is visible, and in between those points is where we’re going to get to Andromeda and the Andromeda Galaxy very nearby. As we turn around to the north, we’ll come to the Plough, already low in the northwest, as the Sun is setting. The Plough is part of the constellation Ursa Major, the Great Bear, but most of the other stars aren’t visible. The Plough is pretty much reaching its lowest point in the sky due north as we come up to our local physical midnight, which is a little bit after 1 o’clock in the morning. That puts the Plough, as low as it’s going to get, which means Cassiopeia is way up on the other side of the Pole Star, practically as high as it’s going to get. The Pole Star is visible and a little bit of the connected Ursa Minor constellation. However, the glow of light pollution is blocking out most of Draco, and basically all of Camelopardalis and Lynx, the other constellations around Ursa Minor.

We’ll continue forward towards morning time and the Plough will rise up on the other side of the sky, coming over towards the northeast. Jupiter and Mars will have risen, so that’s Cancer the Crab with Jupiter and Gemini the Twins with Mars. The Moon is still up in Taurus, and Orion has risen as well just below it. At 5:20 in the morning, even early in September, but we’re barely getting a glow of the Sun, so these things are going to be visible. Just east of Orion is Procyon, the Dog Star in the Little Star Canis Minor. Sirius is below Orion, the brightest star in the sky is the true Dog Star in Canis Major. Sirius is still visible even as the Sun rises, coming up to 6 o’clock, along with a scattering of the planets and the Moon. The Moon and the planets are really showing us where the zodiacal constellations are. First we’ve got Leo, just emerging from behind the Sun because we’re just leaving August. Then we’ve got Jupiter in the claws of Cancer and Mars between the Twins in Gemini. The Moon is just at the back of Taurus, next to Aries, and then Saturn is on almost the far side of Pisces. So those planets are really helping us to map out the zodiac.

If we quickly move forward to the end of the month, or at least to the equinox, that will change things. The sky is darker at the same time and Leo is fully above the horizon there. The sickle of Leo would be visible, at least part of it, even from the city. Cancer the Crab is practically invisible, even when you can see the stars in Cancer, it’s very hard to recognize. We just need to remember that it’s between Leo and Gemini, which are both reasonable constellations to see. For September, Jupiter is also just about in its claws. However, the planets really seem to have moved here relative to the stars, even in the space of just a month. Mars, of course, is orbiting the Sun quite quickly, so we would expect its motion. Jupiter is orbiting the Sun quite slowly, but thanks to the constellations highlighting the positions in the sky, we can tell that Jupiter is moving from between the claws of the crab to out of the claws of the crab. Saturn is still in Pisces and that also means Neptune is in Pisces. We’ll move forward to the date of Neptune’s opposition, which I believe is the 25th, although it did take a little bit of messing around to get the exact date of the opposition, likely due to our local time zone.

We will move on from the constellations and take a closer look at Neptune. We are seeing it at 100% full and 4319.724 million kilometers away, which is pretty close to the closest we’re going to get. That’s Neptune at opposition, unfortunately, with the Moon nearby in the sky and close to full. Neptune and Saturn are very close together, and if we move forward just a few days, on to the 4th of October, Saturn will be directly in the south at our local midnight. It’s up to 100% full, and we’re seeing it at just 1261.749 million kilometers away. Taking a closer look at Saturn, its rings actually look pretty visible at the moment, which is always nice to see. It looks like on the 5th, we’re getting it down to 1261.23 million kilometers. So it looks like it is the 5th of October, just past midnight with our UTC +1 summer time, that we’re seeing it at its closest from here in Ireland. Of course, the Earth is a few thousand kilometers thick, so where you are on the Earth will make a difference to how close you are to the planets if you’re measuring them in kilometers. When you’re measuring them in AU, it won’t make a noticeable difference,

Saturn comes to its opposition just a little bit after Neptune came to its opposition and that’s because Neptune is just further ahead in our sky at the moment. However, Neptune orbits the Sun more slowly than Saturn so if we start moving forward here, we can see Saturn almost catching up to Neptune. However, around opposition, outer planets that are at opposition, look like they’re behaving a little bit strangely in the sky. Starting a few months ago and moving forward, Saturn appears to be moving back towards the Sun. It stops, and then it appears to start moving forward again. We come up to our opposition and it almost starts to slow down and move backwards. This apparent motion of Saturn is because it’s at opposition, this is really our motion around the Sun changing how Saturn is appearing to move. Saturn is orbiting the Sun faster than Neptune, but it looks like Saturn and Neptune are getting further apart, and that is partly because of the way we’re moving around the Sun. We’re looking at them from a different perspective at different times of the year.

Saturn is so bright, we’re able to see it even when the Moon is in frame, that’s harder to do with Neptune. We’ll zoom in closer to Neptune so we get a better idea of how it’s moving compared to the background stars and it is doing that little retrograde motion as well. The apparent direction of Neptune appears to move against the flow of the background stars, the direction that we would expect it to move in and that happens as our relative position to Neptune changes. Neptune is just orbiting around the Sun, making a normal ellipse around the Sun, but because we’re also circling the Sun, how we see Neptune in the sky changes. It looks like Neptune’s moving forwards and backwards, but that’s really just us catching up to it and then pulling ahead of it and Neptune seeming to fall behind.

That is two oppositions that are coming up in the near future, as well as the constellations in September. It is very hard to see that kind of retrograde motion in the actual sky, but now at least you’ll know it’s happening and why. I hope that you enjoyed reading this piece, if you did then please do like it. If you like this kind of content, then 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.