Comet 12P/Pons-Brooks reaches perihelion, its closest approach to the Sun this week, and should be at its brightest. Find out how you can see them for yourself as well as our usual stargazing highlights in this week’s podcast guide, Star Diary, 15 to 21 April 2024.
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Chris: Hello and welcome to Star Diary, the podcast from the makers of BBC Sky at Night Magazine. You can subscribe to the digital edition of the magazine by visiting iTunes, Google Play, or Apple News, or to the print edition by visiting skyatnightmagazine.com.
Ezzy: Greetings listeners, and welcome to Star Diary. A weekly guide to the best things to see in the northern hemisphere’s night sky. As we are based here in the UK, all times are in BST. In this episode, we’ll be covering the coming week from 15 to 21 April. I’m Ezzy Pearson, the magazine’s features editor and I’m joined on the podcast today by Katrin Raynor, an astronomer and astronomy writer.
Hello, Katrin.
Katrin: Hello, Ezzy. How are you?
Ezzy: I’m doing well. So what do we have coming up in this week’s night sky?
Katrin: As we pass the middle of April, we have the start of another meteor shower and a planetary conjunction, which is going to be tricky to observe. The Moon is going to delight us this week with a few clair obscur effects, which appeal to adults and younger observers alike.
You know, they’re real… great fun to spot. So the Solar System, well, on 19th, the Eta Aquarid meteor shower begins. But it doesn’t peak until the beginning of May, when it may be possible to see around 50 meteors per hour.
So these meteors originate from the consultation of Aquarius and is debris left over from Halley’s comets.
Unfortunately, the shower is more prominent in the southern hemisphere and appears in the early pre dawn hours at northerly latitudes. But it will be possible to see some meteors in the eastern sky.
And conjunction wise with the planets, on 20th we have Jupiter and Uranus. They’re reaching conjunction, separated by just half a degree. And they’re going to be low on the western horizon in the dusk glow.
Bright Jupiter will be easy to spot, however Uranus is going to be a bit more tricky. So grab a pair of binoculars or a telescope to see the conjunction after 9PM BST. And Comet Pons-Brooks passes into the constellation of Taurus the Bull.
Speaking of the comets, Comet Pons-Brooks reaches perihelion on 21st.
So perihelion is when an orbiting body passes at its closest point to the Sun. And the comet should be at its predicted maximum brightness of magnitude +4.5, which means it may be visible with the naked eye in the western horizon. Perihelion, I think my astronomy teacher a few years ago, to remember perihelion and aphelion. He always said, perihelion meaning perilous, it’s close to the Sun.
So I also, that was a really good way of remembering.
Ezzy: Yeah. That is one that took me a while to get my head around. For me, it’s aphelion is it’s afar. Which is… I think yours is better.
Katrin: Yeah. Peri. Perilous. It’s going to get burned up by the S
un or something. I don’t know. It’s too close.
Ezzy: Yeah. The thing I always get slightly mixed up in my brain is the fact that when it’s a perihelion, it doesn’t necessarily mean it’s hidden behind the Sun.
Because to me, it’s like when it’s its closest, oh, that must be when it’s on the other side of the Sun. But that’s not actually what happens at all because of the way that our orbits are aligned and everything like that. Sometimes we can be looking at it sideways on when it’s passing close to the Sun.
Sometimes, comets do pop behind the Sun for a bit and can’t see them. But we should be able to see it when it’s passing through perihelion.
Katrin: And similar to that, actually, I will think if it’s closer to Earth. Then we’ll be able to see it better, but obviously that’s not the case. So there’s always like these nuances and it’s like, ooh.
Ezzy: When it’s closer to the Sun it’s giving off more gas. It’s hotter so it’s giving off more gas and more dust. So it’s got a bigger tail and coma and we can see it and it’s more bright. But it’s also sometimes further away than other times. And it’s this kind of like balance. And also comets are just notoriously unpredictable.
Katrin: They are.
Ezzy: You’re never sure what they’re going to do. I mean, it might be that comet Pons-Brooks doesn’t survive its encounter with perihelion. Sometimes comets do just break up. Hopefully it won’t, hopefully we’ll have a couple more weeks of it gracing our night skies still to come.
Katrin: Yes, I mean we deserve a good comet, don’t we really. But just to say it is going to be a challenging object to view in the twilight sky. By the end of the month it’s going to disappear into the evening twilight, so make the most of any clear nights to get out and observe it.
So the Moon, we have a couple of clair obscur effects to look out for this week. If you’re not familiar with this term, clair obscur is the interplay of light and shadow as the Moon changes its phases. So it’s possible to see faces, letters, and star clusters on the Moon caused by the changing light and shadow.
And as I mentioned earlier, these are just great effects to spot. They’re real fun. I think, you know, it’s a good opportunity for kids to get involved. It might spark their interest. And yeah, I’ve seen, you know, a few of these effects now. And I remember the first time I saw Lunar X and V, I was like, “Oh,” yeah, you know, you can see the actual, the letters on the Moon.
It was brilliant.
Ezzy: Some of them are definitely easier to see than others. And some of them are much more obvious. Like, why is the Lunar X called the Lunar X? Because it looks like an X. So you know what you’re looking for.
Katrin: Yeah. I mean, a bit like the Jewelled Handle effect. I’m like, oh, it’s going to be bright and sparkly, but you know, it’s not. But worthwhile seeing. And I will be talking about this in a minute.
But 16 April, we have two effects to look out for on the morning of 16th as the Moon starts to set in the western sky. So we have Lunar X and Lunar V. It should be visible along the terminator. And the terminator is the line separating the light and the dark sides of the Moon.
So the X appears when sunlight skims the rims of the adjoining craters, Blanchinus, La Caille and Purbach at the same time, so their interiors are still steeped in shadow. Excuse my pronunciation there. I think we were talking earlier, weren’t we Ezzy, that because astronomy can be a lone hobby, if you like. Sometimes when you’re coming across these words, you’ve got no one to turn to and say, “well, how do I pronounce these?”
Ezzy: It also doesn’t help that it’s so many things are just a mismatch of all these different languages. You know, you’ve got some which are French and some which are Latin. Then there’s occasional Arabic one gets chucked in there as well, some Chinese. It’s just, I don’t know what pronunciation scheme I’m following here.
So, I think, just try your best.
Katrin: Sure and people pronounce them differently as well, don’t they? So it’s a bit like the tom-ah-to, tom-ay-to thing.
Ezzy: Yeah.
Katrin: But, you know, they’re still right. We’re both right, no matter how you pronounce it.
Farther north along the terminator, look for the Lunar V at the same time.
The slanted sunlight highlights two converging ridges of Mare Imbrium ejecta and the eroded rims of the craters Ukert M and N, located just east of Ukert. So I think you are going to have to kind of take to the internet or dig out your Moon map to locate these craters. There’s so many on the Moon, you know, if I was trying to tell you how to view these now, I’d probably be here for a long time.
Ezzy: Well, as usual, we have guides on how to locate the Lunar X and the Lunar V, and many craters on the Moon as well, over on our website, skyatnightmagazine.com. So if you are trying to find anywhere in particular, that’s always a good place to start.
Katrin: Moving on to 18th, so two days later after you’ve hopefully managed to spot Lunar X and Lunar V, the Jewelled Handle will be visible, which is best through binoculars or a small telescope.
So if you locate the 77% waxing gibbous Moon around 7PM BST, you’ll be able to see the illuminated arc of the Jura Mountains that border Sinus Iridum, the Bay of Rainbows, which is a semi circular bay located on the northwest region of the Moon. And I do think the Jewelled Handle will probably be a lot easier to spot than Lunar X and V.
So yeah, a lot to see, I think, on the Moon. Lots of exciting effects. So keep an eye out for.
Ezzy: Yeah, I think it’s also one of those things that’s really lovely about the Moon is because not only does it have these phases, which it changes every day, because it’s also got the libration. So that’s sort of like the Moon’s wobble a bit.
No two months are the same, even if you’re looking at when the sort of like the same phase, the light and the shadow is always slightly different. So it does change when you’re looking at it. So it’s well worth having a closer look at the Moon whenever you can.
Katrin: Like I said a few weeks ago, you know, I just, I love looking at the Moon, except when there is a meteor shower happening around the time.
Ezzy: Except when there’s a meteor shower.
Katrin: I think the Moon’s a bit like Marmite then, isn’t it? You either love it or hate it.
Ezzy: I think you sometimes love it and you sometimes hate it.
Katrin: Yes. We’re loving it this week. So just to end the week on 16th, this week’s dark sky object will create a real buzz, which is a terrible joke, because I’m going to talk about the Beehive Cluster.
So whilst you’re out on the night of 16th looking for Lunar X and V, take a trip to the constellation of Cancer to see the 60% waxing Moon, and sitting 3.3º northeast of M44, which is the Beehive Cluster, and it’s an open star cluster and one of the closest star clusters to Earth. I think Mary may have mentioned this a few weeks ago, so grab a pair of binoculars. Locate your gaze downwards from the Moon to find this area of glittering stars.
It is possible to see the cluster with the naked eye from dark sky sites, but it’s a popular pit stop for astronomers when conjunctions with the Moon or planets occur.
Ezzy: We often talk about when the Moon’s going to be passing the Beehive Cluster because the two do look very good together. Yeah. And as usual, if anybody does take a picture of that or any of the other things we’ve mentioned this week, please do send them in to us at skyatnightmagazine.com. Find the details in the notes below. We always love seeing your images and we print the best pictures in the magazine every month.
So hopefully there’ll be something in this week’s night sky that you’ll be able to get out there and have a look at. And thank you, Katrin, for taking us through all of them.
If at home you want to make sure that you are kept up to date with all of the latest goings on in the night sky, please do subscribe to the podcast and we will hopefully see you here next week.
But to just summarise this week again, we start off on 19th with the Eta Aquarid meteor shower which will just be beginning on 19th.
On 20th, Jupiter and Uranus are going to be in conjunction, so you get to see the two of those together.
On 21st, Comet Pons-Brooks is going to be reaching perihelion and will be at its brightest. It’s going to be disappearing out of our skies in the next couple of weeks, so definitely try to get a glimpse of that whilst you still can.
Over on the Moon, we’ve got several clair obscur effects which are definitely worth looking for. On 16 April, the Lunar X and V will both be visible along the terminator.
On the 18th, the Jewelled Handle will be on show near to the Bay of Rainbows.
And finally, on 16th as well, look out towards the Beehive Cluster where you’ll be able to see it next to the 60% waxing Moon.
So lots of really good things to see in the night sky. Thank you very much again Katrin for taking us through all of those and we’ll hopefully see all of you back here next week. Goodbye!
If you want to find out even more spectacular sights that will be gracing the night sky this month, be sure to pick up a copy of BBC Sky at Night magazine where we have a 16 page pull out sky guide with a full overview of everything worth looking up for throughout the whole month. Whether you like to look at the Moon, the planets, or the deep sky.
Whether you use binoculars, telescopes, or neither, our sky guide has got you covered. With detailed star charts to help you track your way across the night sky. From all of us here at BBC Sky at Night Magazine, goodbye.
Chris: Thank you for listening to this episode of the Star Diary podcast from the makers of BBC Sky at Night Magazine.
Which was edited by Lewis Dobbs. For more of our podcasts, visit our website at skyatnightmagazine.com/podcasts, or head to Spotify, iTunes or your favorite podcast player.