Catch the Milky Way this month before it disappears into the twilight. Find out how to catch these and more stargazing highlights in this week’s podcast guide, Star Diary, 13 to 19 May 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 www.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 13 to 19 May. I'm features editor Ezzy Pearson, and I'm joined this week by Mary McIntyre, an outreach astronomer and communicator.
Hello Mary!
Mary: Hi Ezzy!
Ezzy: So, what have we got to look forward to this week?
Mary: Well, coming up this week, we've got a couple of planets to see in the dawn sky, four asteroids to look for, lots of lunar conjunctions and clair obscure effects, a couple of faint comets and possibly our last chance to catch the Milky Way before it gets lost in the twilight of the summer months. And then we may possibly start seeing some clouds in space this month.
So I'll start with the planets. Evening sky, no bright planets visible still. We don't have anything to look at there in terms of bright planets, but we can still see the asteroids Pallas, Vesta and Juno.
Pallas reaches opposition on 17 May, so that is visible in Hercules all night long. You will need binoculars to see it. As we always say on the show, we try to get the message out there that something being at opposition is not the only night you can see it. Like, if it's at opposition, you can see it all month easily. So, as the last three weeks, if you haven't had a chance to look for Pallas, there is still plenty of time to do that this week.
Ezzy: The difference between something being at opposition and a day, even a week or two, either side, unless you're taking photographs and comparing them, and even then you're probably not going to notice that much of a difference.
Mary: So that one is in Hercules, but Vesta is kind of in the centre of Gemini, which is now getting quite low in the west after sunset, but you can still catch a glimpse of Vesta there.
Mag +8.4, so technically a bit brighter than Pallas, but it is going to be kind of more in the twilighty bit of the sky. But you should still be able to spot it. The fainter one of the three asteroids is Juno, which is at mag +10.3. That lies below Leo after sunset, so that's really well placed and stays visible until it sets at about 3 o'clock in the morning.
So you've got plenty of opportunity for looking at those three asteroids and just note how they move against the background stars over the week. Moving over to the morning sky, Saturn lies in Aquarius and is rising at about 3:30 in the morning, only at about mag +1.1 at the moment, but it is naked eye visible.
Mars, similar magnitude in Pisces and rising about half an hour later over in the east.
To the left of The Teapot we have the asteroid Ceres, that is mag +8.2, so that should be an easy asteroid to spot with binoculars. That is rising at about 1:30 in the morning. So again, I love anything that's near The Teapot, any opportunity to go and have a look at The Teapot is good by me.
So moving on to the Moon and some lunar conjunctions, the Moon this week is heading towards first quarter phase – my absolute favourite time for spotting southern hemisphere lunar craters and it's also the time where there are the most number of clair obscur effects to look for, so I'll talk about those and some of the conjunctions that we have coming up.
On 13/14 May overnight we have a waxing crescent Moon to the upper right of M44, the Beehive Cluster, so that'll be really nice to observe. At half past midnight that night, it's going to be just under 3º away from the Beehive, so through binoculars you'll easily be able to see the cluster very near to the Moon.
On 14 May, there's a feature called Rupis Altai, which is one of the most prominent lunar escarpments, and it's a really good time to observe this.
You can see it for like a couple of nights around this phase of the Moon. It's kind of on the southwest boundary of the basin of Mare Nectaris, and it's where there are two areas of instability and one has slipped down so you can kind of see this ridge. It's just basically where one part of it is higher than the other and the ground has just basically slipped down. And when it's illuminated properly you can get a really good view of that.
So a way to find that is to look for the Theophilus Trio which is a really obvious trio of craters at this lunar phase and just look below that a little bit and you will find Rupis Altai. Bit of interesting trivia about Theophilus Trio. The bottom crater of that is named Catherina, and that is based on a martyr whose life is thought to be based on Hypatia, who was a real person who was an early astronomer.
Hypatia has a crater just above the Theophilus trio. There are only about 1.8% of lunar craters named for women and Hypatia inadvertently got two named after her because Katharina is based on Hypatia. So I think it's awesome that she got two when most people don't get any. So, interesting, not related factoid about the Theophilus trio that I quite enjoy.
On 15 May at 5:00 PM the Lunar X and V are visible, and that's just basically where you see the sunlight hitting the craters and it forms an X. So kind of YX on the shadow side of the Moon. And then a little bit further up, you can see the V just a little bit further onto the right. They're still one of my favourite clair obscur effects.
I just think they're awesome. And then a few hours later, we have the Face in Albategnius in Albategnius Crater a little bit further up from where the Luna X is. Later that night at about 10 o'clock, the waxing gibbous Moon is going to be less than 3º above the star Regulus, so that's always a nice one to look for.
On 17 May at 2:23, a very specific time, we have another clair obscur effect called Plato's Hook. There's a guide to see this in the magazine's Sky [Guide], but basically the crater Plato has a diameter of about 109km. And when you look at it, picture of it fully illuminated it looks like the crater rim is all the same size all the way around as it does with many craters but when you look at the shadows being cast with a low Sun angle you can see that's very much not the case.
And Plato is particularly full of peaks and troughs and sharp jagged shadows they just look really beautiful but Plato's Hook is this kind of curved shadow and there's just something about the topology of the crater wall creates this beautiful hook shaped curved shadow which is visible for a really small amount of time and we can get to see it.
It's only about 45 minutes before the Moon sets but definitely worth looking for.
Ezzy: I think it is always amazing how you think their shadows they should just all be straightforward but they can still cast these incredible shapes because the thing casting the shadow isn't entirely level. It can have all of these kind of wonderful shapes to it and then it's casting it on something that's probably not entirely flat and all of these things together can create some absolutely magnificent effects you just need to know when and where to look.
Mary: Yeah, there's always a guide for this month's clair obscur effects in the magazine Sky [Guide].
On 18 May, look for the Jewelled Handle, which is the rim of Sinus Iridum being brightly illuminated as the Moon rises. It's not ideal for us from here in the UK, because it will be a daytime Moon when that occurs, but you can still see it.
It's one of those areas that is so brightly lit against the background that you can still see it on a daytime Moon, but obviously it won't be as dramatic as when you see it on a nighttime Moon.
Also on 18 May at about 10:00PM we've got a waxing gibbous Moon just 58 arc minutes below Zaniah in Virgo, so that is a really close conjunction.
That star is mag +3.8, so you may need binoculars because the glare of the Moon may actually make that not visible very easily to the naked eye, but that is a very very close conjunction. So if you do notice a star near the Moon that night, that's what it will be.
All through 19 May is a good time to look for Cassini's Moon Maiden. Cassini named, like looking at some of the features of the Moon through a telescope that flip things upside down, the edge of Sinus Iridum upside down and in the right light looks like a lady with long flowing hair. So that was named after Genevieve, his wife, and so it's a one of those clair obscur effects that isn't time critical, you can actually see it for a couple of days, two or three days around this Moon phase, but definitely look for that on 19th.
And also at 11 o'clock on 19th, we've got a waxing gibbous Moon just 6º away from Spica. So that's it for Moon and lunar conjunctions.
We do also have a couple of comets. Comet 13P/Olbers is moving into Auriga this week. That is going to be visible at about 10:45 at night, 8º above the west northwest horizon.
On 13 May, it's going to be halfway between Elnath and Hassaleh, so it's a good time to kind of use those two stars to try to see if you can spot the comet, because comets, without a kind of camera to help you, just looking at comets through binoculars can be a bit tricky. So if you're not very experienced at finding comets, It's a good time to try to find it when it's bang in the middle between two stars because it can really help you land on it.
That comet is about mag +9.0 at the moment. It will be brightening as we head towards 1 July. It may get brighter than that sooner. We never know what comets are going to do. They are a lot unto themselves, but definitely a good time to look for that and keep an eye on it over the coming weeks.
S3 PanSTARRS is still fading, so it should be at around about mag +11.5, which is kind of getting into big telescope kind of photographic target territory, but definitely still worth looking for. It's in Cygnus. Cygnus is a beautiful part of the sky to do astrophotography because it's so full of nebulosity, so if the comet is nestled within that, it always makes a beautiful photograph.
Now, while the Moon is setting kind of around about midnight around first quarter, it means that there is no Moon washing out the dawn sky.
And at the moment, the Milky Way is rising kind of over in the east. So it's a really good time to get a good look at the Milky Way because by the time we go through another lunar cycle, we're going to be into the point where a lot of the UK doesn't get true darkness because of the summer months.
So, although the Milky Way is higher in June, it's almost harder to observe because, certainly, north of the Midlands, it just doesn't get dark enough to really see it that well.
Ezzy: Yeah.
Mary: And it can be really tricky at that time of year, so I like to observe it in the dawn sky at this time of year, partly also because it's not quite as high, and if you're into photography, trying to get the whole arch of the Milky Way is actually really beautiful in a photograph rather than it looking like a straight line.
And when it's lower in the sky, it's easier to do that. So I think the Milky Way is beautiful at this time of year. So before dawn in that hour before sunrise, really before you start getting the twilight effect in the sky, the arch is going to be about 55º above the eastern horizon, so it's not like it's hugging the horizon. It's at a decent height, but no one talks about the Milky Way at this time of year. It's always Milky Way in June, and get in now, because once we've got a full Moon in the way, we're not going to see it then probably until July or August.
So, definitely worth a look.
Ezzy: You also mentioned there the fact that you could get an arch across the sky, because that is the sort of thing that I think a lot of photographs don't get across, is it is not just this one thing in one place. It goes across the whole way and it curves around us with the sky.
If you could see it all the way around the Earth, it goes right the way around the Earth, though a bit less dense in other places. So you know, it's our view through the Milky Way galaxy, through our Galaxy towards that galactic centre. So there's some really beautiful things in there to see.
Mary: Yeah, if you look for The Teapot in the claw of Scorpius, the Galactic core region. We don't see all of the Galactic core from the UK at any time of year, but we're starting to see the bits that are near it, and then you can get all that lovely colour and shapes, and if you look at that area with binoculars it is mesmerising.
There's so many star clusters. So much gas and dust. It's just... it is beautiful. Even if you don't photograph it, just get your binoculars on that southern bit of the Milky Way in between The Teapot and Scorpius. It's just absolutely breathtaking.
Ezzy: I always say that was the thing that got me into space and astronomy really properly was when I was seven and I was in Cornwall.
It was the first time I looked up and actually could see the Milky Way and it was just there in the night sky and that was it. I was done.
Mary: Yeah, I'm very lucky that I live somewhere where we can see it. And although I'm not a fan of LED lighting from a biodiversity perspective, the ones they fitted in our village have made a huge difference to our night sky.
So our Milky Way view is actually better since they changed the street lights. So I'm very grateful for that.
There's another thing that you can hopefully see at this time of year. It's the start of noctilucent cloud season. Noctilucent clouds are a type of polar mesospheric cloud, so they're really high up in space, like kind of right up on the boundary of space.
They cluster around the North Pole and they can only form in the summer months because the layers of atmosphere above where we are get colder when it's hotter lower down. So it has to be below a certain temperature in order for water to freeze there. There isn't very much water there in the first place, so noctilucent clouds are incredibly difficult to predict.
In theory, their season starts at the end of May.
However, although we don't really fully understand noctilucent clouds, there seems to be a link in the presence of noctilucent clouds and solar activity. As in, the more solar activity we have, the more UV hits the atmosphere, therefore more water gets dissociated, therefore no noctilucent clouds.
We are heading towards solar max. Last season was an absolute disaster for noctilucent clouds, and I've got a terrible feeling it's going to be like that again. But you just never know, that's the thing. If we have a quiet couple of weeks on the Sun, you just never know when something might just trigger the formation of those clouds.
So from the UK, you need to look in the north about an hour after sunset and they are so high that they're still getting illuminated by the Sun when our atmosphere is in shadow and they are my, probably my favourite thing to observe. I am obsessed. I'm literally obsessed.
Ezzy: Just because something isn't going to be common throughout the year doesn't mean it's not going to happen throughout the year.
So especially if you're out and about anyway in the evenings, just keep your eyes on that horizon and see if you can happen to see anything.
Mary: Yeah, they've got this kind of ethereal, bluish white glow about them, and there's no doubt that June is usually a better time for it, June, July. But it's not unheard of for them to appear at the end of May, so just keep an eye on that.
And it's one of those things, because they're so poorly understood, Observing them and sending those observations into the BAA or the SPA is so important so that we can keep a track of their behavior, because we cannot predict them at this point, we don't know what they're doing, they're such a mysterious object still.
And they were first observed in the late 1800s, so it's believed that global warming is part of the reason they conform, but it's still mysterious. There's a lot we don't know about them.
Ezzy: Yeah. Since you mentioned that, it's one of those things to bear in mind is that when the ground is warmer, the mesosphere gets colder.
So that's one of the things that they think is, is triggering it because the climate on the ground is getting slightly warmer. It's making that area a bit colder, which does sort of create them. There is a lot more to it than that.
There is a, like, weather is a branch of science that I just don't understand how people manage to make any sense of this. There's so much going on. Being able to predict anything beyond about five minutes in the future is just, when you look into it, it's just amazing.
Mary: It's crazy. But you can see, noctilucent clouds are normally hugging the northern horizon from most of the UK, so you see them an hour to 90 minutes after sunset or about 90 minutes before to an hour before sunrise. Which around midsummer means all night long, which means Mary is very sleep deprived and very grumpy in the summer because she's up all night looking for noctilucent clouds. But there are actually webcams across Northern Europe pointing north that are looking to monitor them.
So what I tend to do is set an alarm, look at the webcams, is it worth getting up? Because it gets light an hour earlier there. If they're seeing them in Germany then it's worth getting up and going to my site where I can see the northern horizon better. So there are some things that can help you not be quite so sleep deprived.
If there's nothing happening on the webcams, I just go back to sleep. So, you know, there are things out there to help.
Ezzy: The great thing about the night sky, and the day sky as well, being this thing that everybody has access to. Some people have it better than others because they live in a darker place, but everybody can see the night sky, which means everybody can work together to work out what's on show today, what you can go and see, and it's a wonderful collaborative thing, I think.
Mary: It is, and there's loads of hashtags as well on social media, like #NLCNow, so if observers see Noctilucent Clouds, they are hashtagging it across all socials so everybody knows it's happening. So it's a lovely community of people that you know, have a common goal, and that is to get everybody to see Noctilucent Clouds, which is lovely.
Ezzy: Also means if anybody at home happens to see one in the night sky, make sure everybody else knows. Make sure you tell other people about it.
Mary: Definitely. So that's everything for this week.
Ezzy: Well, thank you very much for taking us through all of that, Mary. And if our listeners at home want to keep up to date with all of the highlights in coming weeks, please do subscribe to the Star Diary podcast.
But to summarise this week again, starting with the planets, there's not very many good evening planets at the moment, but Pallas will be clearly visible all night long, Vesta is getting low but still visible, and Juno is visible until about 3:00AM in the evening sky.
Looking in the morning sky, Saturn and Mars are still on show, and Ceres will also be in The Teapot as well.
Looking at the Moon, it will be in first quarter phase on 15 May. But earlier in the week, on 13/14, the Crescent will be near the Beehive Cluster.
On 14th, it's a good chance to see Rupes Altai, a lunar feature called an escarpment on the surface of the Moon.
On 15th, it's a great chance to see clair obscur effects, the lunar X and lunar V, as well as the face in Albertegnius.
Also on 15th, the Moon will be appearing close to Regulus.
17th is a great chance to see Plato's Hook for a brief period of time. Make sure you look up your timings on that one.
18th is a great chance to see the Jewelled Handle and, also the Moon will be below Zaniah in Virgo as well. Then on 19th is a opportunity to see another clair obscur effect, the Moon Maiden. Cassini's Moon Maiden, and the Moon will also be appearing near Spica as well.
In terms of comets, we have 13P Olbers in Auriga. Might be a good chance to see it on 13 May where it will be between Elnath and Hassaleh, two stars in Auriga. In case you need a bit of help finding your way to the comet there.
And S3 PanSTARRS is still visible in the night sky. It's rapidly becoming a photography target but still visible for you there.
It's a great time of year to look at the Milky Way as well when it's nice and high in the sky but still dark enough to be able to see it properly. And of course, it's the start of noctilucent cloud season – high clouds on the boundary of space. The season starts in late May and will be visible for an hour to 90 minutes after sunset or before sunrise.
So keep an eye out for all of those and hopefully we will see you all 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, or 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 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 favourite podcast player.
Listen to the next episode of Star Diary: Have you ever seen a hamburger in the sky? (20 to 26 May).
