Caoimhín's Content

Today we are finally going to take a look at Comet 141P/Machholz. I mentioned this comet a few pieces ago when we were taking a look at the conjunction of planets that is visible early in the morning if you are closer to the equator. This comet and the planets will be above the horizon if you are at a lower latitude, you don’t have to be too close to the equator, just closer then Ireland.

With the atmosphere removed, we can see the planets in the morning even from higher latitudes. If we take a slightly closer look, Comet 141P-D/Machholz is right next to the planets. A bit closer to the Sun is Comet C/2025 R3 PANSTARRS, there are a few comets around at the moment, but Comet Machholz is a little bit faint. It’s just magnitude 9.8, and that’s with the atmosphere removed. If the atmosphere was still there, it would be reduced by the air masses, making it even fainter. Even if you’re seeing it in a dark enough sky, a little bit higher from the horizon, 9.8 is about as bright as it’s going to get, which is pretty faint. That does make it a potential target for telescopes, but it’s not a particularly bright one. Comet 141 P-D/Machholzs is one of many comets that’s named after Donald Machholz, so this comet is sometimes called Machholz 2. Comet 96P/Machholz gets called Machholz 1, even though there are 12 comets named after Donald Machholz who discovered all 12 of them.

Just next to Mercury is where the comet will be as of the morning of the 24th here in Ireland, so it’s quite close to those planets in our sky. It’s already quite close to the Sun, it’s under an AU from the Sun, but it’s over an AU from us, so this indicates that the comet is on the far side of the Sun from us. As we move into the future, just around the 18th or 19th of May, the comet gets down to 0.8 AU from the Sun, more or less. That’s the closest that it’s going to get, it will then start moving away from the Sun. However, from our perspective, it looks like it’s going behind the Sun, it looks like it’s getting closer to the Sun in our sky. Really that’s just because the comet is leaving the solar system on the opposite side of the Sun from us. That’s something we’d be able to see a little bit better if we head out to the solar system observer and take a look down on this comet from above so that we can see the path that it’s taking relative to the Earth. Looking down on the solar system with the comets orbit highlighted, it goes from just past Jupiter to just inside the Earth’s orbits. Jupiter’s orbit does go pretty close to the orbit of this comet, so this comet can have its orbit changed by proximity to Jupiter. Right now, the comet is pretty much on the far side of the Sun. It reaches its closest position to the Sun pretty much on the opposite side of the Sun from us, and then continues out of the solar system, while on the opposite side of the Sun from us, as we both travel in the same direction.

The Earth’s orbit seems to be cutting through the orbit of this comet, the orbit of this comet just barely comes inside the Earth. Its closest position to the Sun is just under an AU, so just barely closer to the Sun than we are. After its perihelion almost on the opposite side of the Sun from us, it then continues out back out, not too far into the outer solar system, just about as far as Jupiter. It does appear that the Earth orbit is crossing the orbit of this comet, but sometimes this can be an illusion. The comet could be going above or below the plane of the ecliptic, as we’re looking down on a 2D projection of a 3D Solar System. In this case, this comet is going pretty close to the orbit of the Earth. Not all comets leave behind particularly big streams of material and very often the biggest streams of material that get left behind are left behind by comets that break up or at least partially break up as they go around the Sun.

Comet Machholz’s orbit takes a little over five years. It’s having its perihelion just coming up in May, and it won’t come back around again for a little over five years. It is a periodical comet, and it is a pretty short period comet. Five years is a very short orbit for a comet, most comets would have much longer orbits. From above, it’s clear that its orbit isn’t going to be too long, just going from Jupiter into about as far as the Earth. This comet probably isn’t going to get ripped apart by the Sun, it’s not getting close enough. Other comets do get close enough to get ripped apart by the Sun. Comets can get too close to Jupiter as well, the Shoemaker-Levy 9 comet was broken up and taken in by Jupiter, it crashed into Jupiter. Comets do occasionally break up, whether it’s due to the influence of the Sun or planets, or just getting flung out of the solar system, which does happen occasionally.

Next, I want to take a look at Comet 26P/Grig-Skjellerup. In Stellarium, it seems to be listed without its number, but I’m pretty sure that this comet is the only comet that was discovered by this pair of astronomers, which does make things a little bit simpler. It has a just under five year orbital period, but it’s currently quite far out. It’s 4 and a half AU, give or take, from the Sun, about 5 and a half AU from us. So just like Comet Machholz, it’s on the opposite side of the Sun. This comet is the comet that gives rise to the Puppid meteor shower. The Puppid meteor shower should be peaking just as we get into the 24th, just as we pass midnight UTC. You can return back to the previous piece to learn a little bit about the Puppids. We’re going back out to the solar system observer to take a look at this comets orbit. We’ll have to travel through a couple of years to see this comet come back to its perihelion. It’s almost, it’s almost as far from the Sun as it’s going to get currently, we’re going to have to move through several years, back to 2023, in order to see this comet closer to the inner solar system.

Looking at the last perihelion, the distance from the Sun is just about 1 AU, but we can get that down to just about 0.7 AU. This puts the comet inside the Earth’s orbit. This comet’s path passes the Earth’s orbit and the Earth passes through the stream left behind by this comet, this is a comet that creates a meteor shower. Looking for where the comet’s distance from the Sun is equal to ours, 1 AU, that’s where it should be intersecting with Earth’s orbit. Then again, the Earth’s orbit is elliptical, it’s not perfect, there are times where the Earth is further from the Sun than 1 AU and closer than 1 AU, 1 AU is just the average. This comet’s path presumably passes the Earth’s orbit more than once, on the way in and on the way out, but where we collide into the stream of material left behind by this comet, that doesn’t happen until the 24th of April. The comet reached a maximum brightness of about magnitude 7. This was back in 2023, and the comet was very close to the Sun in our sky, so it wouldn’t have been a particularly easy comet to see. Some comets, of course, can be very difficult to see.

If we return back to the Earth, as mentioned in the previous piece, we are just past the peak of the Lyrids. The Lyrid meteor shower peaked on the 22nd this month. The Lyrid meteor shower has been recorded since 687 BC. Presumably it took a few years of regular observation before we could be sure that it was the same shower, on the right dates and radiating from the right location. When I say it’s been recorded since 687 BC, there was regular recordings of it at the the time that we know it to happen and that is how we were able to extrapolate that it is the April Lyrids that were being recorded even in 687 BC. Not every meteor shower has that history to it. Some meteor showers have only been discovered more recently, and it wasn’t until the 1800’s that everybody agreed that meteors came from space. There was for a long time a theory that meteors coalesced in the upper atmosphere from dust and then fell back down to the Earth. It wasn’t until the 17/1800s that people really started to accept that these things actually came from space. Really, it was the 1700s that people started saying that meteors came from space, but even into the 1800s it wasn’t a sure thing that meteor showers came from space and it certainly wasn’t known that meteor showers were connected to comets. However, in more recent times, meteor showers have been connected to the stream of material left behind by comets. Sometimes these streams are from comets breaking up more recently, in the past few decades. The meteor showers from those events are younger showers.

Meteor showers, the same way that their parent body comets, can get destroyed, get blown out of their paths and stop coming back in around refilling the stream of material that generates the meteor showers for us, the same way that those comet stories can sort of end, meteor showers can fade out as well. Even though meteor showers have been observed really for almost all of human history, as long as people have been writing things down and talking about what’s in the sky, there’s been discussion of meteor showers, but there’s a good chance that meteor showers seen by our ancestors might not be meteor showers that we see today. The April Lyrids seem to have the longest history, whereas other meteor showers, their periodicity, the fact that they happened at regular times, that only became discovered much more recently, and so we don’t really know which ones are the youngest, which ones are the newest, because we simply haven’t been recording them properly for that long. The Lyrids have a very long history, but not a lot of meteor showers do.

I hope that you get to see maybe Comet 141P/Machholz, or maybe a few of the Puppid meteors over the next couple of days. Most importantly, I hope that you enjoyed this piece. If you did enjoy it 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 watching and hopefully I’ll see you back here next time.