Caoimhín's Content

Today we will be looking ahead at the meteor showers that are coming up in November as well as quickly revisiting the Greatest Elongation of Mercury and taking a quick look at what could have been with Comet C/2024 S1 ATLAS.

Mercury will reach its greatest eastern elongation later this month, meaning it will be at its farthest east of the Sun, making it visible in the West at sunset. As such, we will need to look for Mercury at sunset, and from Ireland at least it will be hard to find under real conditions. If we get rid of the atmosphere and the ground we’ll certainly be able to see Mercury, just in between the Sun and Venus. If we were to move back closer to the beginning of November, Mercury would be just next to the Sun. Moving forwards, we can see that it moves out to the side as we get up to middle and late November and it then reaches it’s maximum. Mercury will appear to sort of freeze there and then turn around on the 17th and 18th. Then, Mercury will continue its orbit and end up moving in front of the Sun. Mercury will look invisible there, which means it’s not reflecting any light in our direction, so it must be in front of the Sun. Going back into October and back in to the month before, then Mercury would appear really bright and lit up, so it must have been behind the Sun then, reflecting light in our direction. That is back around the 2nd of October, when the annular solar eclipse which was visible from down in South America, occurred. With no atmosphere the dark, night side of the Moon would be visible almost in front of the Sun form Ireland.

Coming back to the 17th, Mercury is at its farthest from the Sun. If we were in a location with a perfectly flat horizon, it would be above that horizon. If you’re on a big salt flat or in the middle of the ocean you may get a flat horizon all around. Of course, the ocean isn’t necessarily flat all of the time, massive waves known as rogue waves can occur far out in the ocean, but on a still day, it can be completely flat if you are surrounded by water. There aren’t any salt flats in Ireland, but we can still simulate a completely flat horizon, the zero-horizon. Mercury is above this horizon while the Sun is below it from Ireland, but with the atmosphere turned back on, the sky does not get dark enough for Mercury to really be visible. Taking a closer look into the glow of sunset here, it is above the horizon and its magnitude could be as high as -0.21, but this is reduced to 3.28 by the atmosphere. Mercury is so close to the horizon that its light has to pass through a lot of atmosphere, and that reduction in brightness will cause it to blend in with the orange-yellow glow of the setting Sun. We will not get to see Mercury from here in Ireland, but you will get to see if you are at another location somewhere closer to the equator.

Looking at the 17th-18th, those dates are also the peak of the Leonid meteor shower. Along with the Leonids, we will have the Taurids coming up this month as well. Many of the radiants for November meteor showers are kind of clustered around the Antehelion point. If we take a look at the Southern Taurids, they are peaking quite soon on the 5th of November. They could produce up to 5-10 meteors across the zenith per hour. Later in the month, peaking on the 12th, the Northern Taurids will also have a maximum of around 5, so we’re not really getting a lot of meteors from them. The Taurids may not be a fantastic meteor shower, though some of the few meteors they produce can be bright fireballs. The Alpha Monocerotids are a highly variable shower, usually producing low rates of meteors with occasional bursts of hundreds of meteros per hour for about an hour or so. The Alpha Monocerotids do not flare in this way every year, so they won’t necessary be that good this year. The radiant is also in Canis Minor rather than being in a Monoceros, the boundaries of the constellations shifted around a little bit before they were fully officially defined, and radiants of meteor showers can move a little as well.

The Leonids are the famous shower this month, peaking on the 17th of November. You may remember from a recent piece that going out the morning of the 17th, when the 17th began will give you your highest potential rate 4 to 17 according to this simulation out of 5 to 20 meteors an hour, rather than going out the night of the 17th when it’s ending. This meteor shower can be amazingly good some years, though it’s probably not going to be amazingly good this year. However, with that coming up at the end of November and these other ones happening here closer to the start of November, and the Monocerotids peaking right at the end of November as well, there should be a slightly higher rate of meteors all month long. However, with the Full Moon on the 15th so close to the peaks of the major meteor showers, it is likely to interfere.

On different years the Moon will be in a different location around the Earth on a given date, but the Earth will still pass through the stream of dust left behind by a given comer on the same date every year, because it depends on our position around the Sun. The Alpha Monocerotids do not have a known parent body, indicating that it is a very long period comet. The Leonids do have a known parent body, Comet 55P/Temple-Tuttle. That comet takes its particular orbit around the Sun, and when the Earth passes through the trail of dust left behind by that orbit, that’s when we get the Leonid meteor shower. It’s the same for the Taurids, comet 2P/Enke is the parent of the Southern Taurids, the Northern Taurids seem to be caused by the trail of a fragment from comet 2P/Enke. This puts the radiants and peaks of the Taurids very close together, almost making them the same meteors shower. Even those meteor showers aren’t expected to be incredibly good, we do at least have a few of them going on. There are also the Orionids and the Andromedids, which run into November, but peaked in October. Some of these things can be difficult to predict. Very often, if people say that there’s 7 or 8 meteor showers all going on at the same time and you should, go to see them, many of them will be minor showers. If they’re all minor meteor showers then they’re not going to be quite as impressive as is often implied.

Speaking of things not turning out to be as impressive as was implied, we’re heading back to the 28th of October. This was the perihelion date for Comet C/2024 S1 ATLAS. Taking a closer look at the Sun and this comet is looking incredibly bright, and it would have been, if it didn’t fall apart. If this comet hadn’t fallen apart it would have looked incredibly bright, especially from the Southern Hemisphere, just as it was moving away from the Sun there on October 28th. Unfortunately that comet, it evaporated. The Sun’s gravity, and the heat of the Sun melting the ices and other volatile compounds that were in this comet, they broke it apart. That comet isn’t going to be as impressive as was expected because it’s gone, it’s broken up, we’re not going to get to see it all. The same unpredictability can be true, for example for meteor showers and also for the Northern Lights.

The Northern Lights have been visible from lower latitudes than normal lately and that’s a great thing, we are seeing more and more of the Northern Lights from a more southerly latitude. However, if there’s a solar storm on the night of the Full Moon, the light of the Moon is going to be able to block out some of the Northern Lights. When the Northern Lights are particularly bright and particularly impressive, then they can be visible along with the light of the Full Moon. The Northern Lights can be that bright, but they can also be a little bit fainter, they are quite variable. Clouds can also block the Aurorae, so the Northern Lights aren’t always going to be amazingly clear even when they are occurring.

The Moon will be just past full on the nights that the Leonids are peaking this year. The nearly Full Moon is going to be with us all night long, just interfering that little bit and because the Leonids are in the constellation of Leo, their radiant will come high in the sky close to morning time. As such even if we moved back a night or two away from the peak to get the Moon out of the morning sky, we’ll only have a good level of darkness for a brief period of time. At 6 in the morning, the Moon has pretty much just set on the 14th for example and the glow of the Sun will already be starting to come into the sky. This year may not be the best year for meteors, but that doesn’t mean you shouldn’t go looking for them. Even if you don’t get to see all of the meteors, there is plenty in the night sky to enjoy over this period. There should be some meteors in the sky even though a few of these showers are not peaking on the same dates or are past their peak, or even limited to pretty low numbers like the November Orionids. All the same, they are all going on and they will all contribute some amount of meteors to the sky.

As I feel has almost been a running theme over the past couple of pieces, we don’t always know what’s going to happen, some things are difficult to predict. We can be surprised sometimes, whether it’s a bad surprise like a nova not occurring when we thought it would, or a good surprise like an exceptional Taurids or Andromedids in a year where we didn’t expect it. Even though the meteors may not be as crazy this year as they’re getting made out to be, there should still be some meteors in the sky. Even if you don’t see any meteors, with Mars, Jupiter, the Moon, Saturn, Venus at sunset, Uranus out by the Pleiades and Neptune over by Saturn, there is still at least plenty to see.

I do hope you get to see some meteors over the course of November and fingers crossed, we’ll get to see some more aurorae as well. Until we do, it is still worth going and looking at the sky, if you don’t look at the sky you definitely won’t see any meteors, whether they are there or not. I hope that you enjoyed this quick little run through of those showers and some of the upcoming events, if you did enjoy it please do like it. You can also subscribe to this website and my YouTube channel if you’d like to support more content like this. Hopefully, I’ll see you back here next time.