Both Comet C/2023 A3 Tsuchinshan-ATLAS and 13P Olbers continue to make their way across the night sky. Find out how you can see these for yourself as well as our usual stargazing highlights in this week’s podcast guide, Star Diary, 3 to 9 June 2024.
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Chris Bramley: 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 Pearson: Greetings listeners, and welcome to Star Diary. A weekly guide to the best things to see in the Northern Hemispheres 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 3 to 9 June. I'm features editor Ezzy Pearson, and I'm joined this week by astronomy writer Katrin Raynor.
Hello, Katrin.
Katrin Raynor: Hi, Ezzy. How are you?
Ezzy: I'm doing well. I'm looking forward to finding out what we've got to look forward to in the night sky. So please do tell us.
Katrin: So the planetary saga continues. Unfortunately, there are no planets in the night sky, only the daytime sky, so viewing our planets will be a challenge.
But there will be an opportunity, albeit a tricky one, to see the conjunction between Mercury and Jupiter in the morning sky, if you know what you're doing and what to look for. So again, the focus this week is on the Moon and the constellation of Gemini is worth mentioning as a couple of distant solar objects are close by.
So as usual, I will start with the Moon. The Moon is waning all week and on 6th there will be a new Moon, so for any of our listeners who are not Moon fans, they will be pleased to hear this. So the Moon will be at perigee on the second, meaning that it is at its closest approach to Earth at a distance of approximately 368,000km away.
At this time the Moon is only 23% lit, but you know, if perigee had coincided with a full Moon, we would have experienced what is now widely known as the Supermoon.
Ezzy: Perigee, for anybody who either doesn't know or struggles to tell those things apart, perigee means the closest approach of two things, so it's the point when the Moon is closest to Earth.
And we know it as a Supermoon because it does appear ever so slightly brighter. It's about, I think it's something like 10% bigger and maybe 20% brighter or something like that. It's not a huge difference. You only notice it when you're comparing photographs to each other. It draws people to look at the Moon, so I don't think it's necessarily a bad thing to celebrate the Supermoons.
Katrin: No, this is true. And the media always like to kind of exaggerate, don't they, when there's a Supermoon? People kind of expect it to be this ginormous looking Moon and yeah, it's nothing really that spectacular. But as you said, it's great for people, you know, to get interested in the Moon, I think, isn't it?
And all the myths and the facts and stuff that come along with the Supermoon, you know, all the names and things. I think that's really interesting to read.
So the Moon is 14% lit on 3rd and at around 3:30 in the morning, the crescent Moon and Mars will rise in the east, forming another lovely pairing low in the east as the crescent Moon sits 3.3º north east of the red planet, and another fantastic sight to enjoy after the splendid sight of the Moon and Saturn last week.
And you can still spot Saturn in the morning sky, which has risen earlier than the Moon and Mars in the eastern sky.
Ezzy: I do have to say I have a bit of a soft spot for seeing the crescent Moon and Mars together.
I think it's something about the sort of paleness of the Moon really brings out the red in Mars to me because you can see them so closely together and I just think they look absolutely gorgeous.
Katrin: It's a nice contrast, isn't it, as you say, between like the pale white Moon and Mars being red. Yeah, it's lovely. It's quite magical, isn't it, and romantic.
So also on 4 June, Venus will be at superior conjunction, meaning that it lines up with the Sun on the opposite side of its orbit to Earth. In other words, it's between the Earth and the Sun. So Venus cannot be seen at this time, unfortunately, and we won't actually get to enjoy Venus again until the end of 2024.
On 5 June, in the early morning sky, we have a very thin 2% lit crescent Moon sitting around 6º to the west, northwest of Jupiter. And on 8th, the 7% lit waxing Moon sits within the constellation of Gemini the twins. If you locate the Moon in the northwest at around 10:30PM and see the constellations brightest stars, Castor and Pollux, which form the heads of the twins located above the Moon.
Now Castor's arm points away to bright Capella, the brightest star in Auriga, unmistakably shining in the northwestern sky. And Gemini does host some great deep sky objects, but unfortunately I think because the longer summer nights, you know, are going to make any observations in this constellation not really worth the effort at this time of year.
On 8 and 9 June there is a fantastic lunar observing challenge for those who like to test their observation skills on the Moon and perhaps tick off a lesser known crater on their list. So, although the Moon is nothing but a thin sliver and only 7% lit, it's a great opportunity to try and observe the Humboldt Crater, located on the eastern limb or fringe of the Moon.
Now, Humboldt is one of the largest craters with a diameter of 207km and is named after German philologist Wilhelm von Humboldt. I had to admit I had no idea what a philologist was until I was researching the crater.
Ezzy: I was about to ask.
Katrin: Oh, someone who studies the history of languages, especially by looking closely at literature.
Ezzy: Oh, I think that's why the name sounds familiar! I have a feeling Tolkien was a philologist. I think I've heard that name sort of in association with him because he was very much about the histories and the languages.
Katrin: Okay, yeah, it was a new one on me to be honest. So back to Humboldt Crater. Viewing Humboldt is a challenge to observe because of its position on the Moon and is best viewed when the Moon is in a favourable position in terms of its libration.
So you may be wondering what libration is. Well, just very briefly, from Earth we always see the same side of the Moon because the Moon is gravitationally locked to Earth. So with this in mind, you might think, well, you know, we must only see 50% of the Moon's surface.
Well, we don't, because of the Moon's elliptical orbit around us and its tilt relative to the orbit of Earth, we do actually have the opportunity to see an extra 9% of the Moon's surface. So the Moon effectively oscillates or wobbles, and at certain times of the month we can see past the Moon's north pole and its south pole. So on the nights of 8th and 9th, we say the Moon is at favourable liberation. This opportunity means that observers can view the Humboldt crater through their binoculars or telescope.
So I, for one, will be getting outside and having a go at viewing Humboldt. You know, I tend to just generally stick with what I can directly see on the face of the Moon, so this will be a good opportunity to see something I haven't seen before.
Ezzy: Libration is one of those effects which means that even if you're looking at the Moon at the same point in its phase, if its libration is slightly different, it will look slightly different.
It's what I think gives the Moon kind of its sort of repeatability. Why people keep coming back to it is because it's a slightly different view every time you go. You're not just seeing the same things over and over again exactly as they were the time before.
Katrin: That's it and I do love watching the motion. If you go on the internet and look at video of the libration of the Moon.
It's lovely, it's quite mesmerising.
Ezzy: I've definitely been looking up one of those pictures to put in an article somewhere online and just sat staring at it for about two minutes.
Katrin: It just draws you in, doesn't it? It's like you're in a trance watching libration of the Moon. It's quite relaxing, I like it.
Ezzy: I'm going to try and find a link to one and I'll put one in the show notes below so if people want to see that we'll hopefully be able to show you some libration there.
Katrin: And I think sometimes when you're trying to explain these things, it can be quite hard to visualise, so that is a really good video that explains, you know, what libration actually is.
So Solar System wise, as I mentioned earlier, the only planetary action we will see this month happens in the morning sky. So on 4th, there is a conjunction between Mercury and Jupiter this morning, rising together just half an hour before sunrise, when they will be 33 arc seconds apart. And given the right conditions, such as a clear sky and excellent view of a flat northeast horizon, the planets may be able to be seen through binoculars.
They're actually going to be at their closest, so less than 7 arc minutes apart, at 11:20 in the morning, of course. So the planets are positioned just 12º from the Sun. So, disclaimer alert, as we keep saying, caution must be exercised if you're going to hunt for the planets whether you're using an optical aid or even your naked eye, you really have to know what you're doing here to spot them.
And if you're unsure about risking it, then just don't do it. You don't want to damage your eyes. So I think if you're a beginner...
Ezzy: Not worth it.
Katrin: Yeah. So I think perhaps we'll leave that one to the more seasoned astronomers than if you're a beginner listening to this, it's probably not the best.
Ezzy: It's something to work towards as you improve in your astronomy journey, it might be that one of those come up in the future and you will be able to look at it, so just keep at it.
But for now, you need to be able to see to be able to get there.
Katrin: So Comet C/2023 A3 Tsuchinshan-ATLAS has now moved out of Virgo. The comet is shining at a magnitude of around +9.0 and can be seen in the southwestern sky. And I mentioned earlier that Gemini is the highlight this week. This is because of course the Moon is positioned within the constellation on 8th, but also because Vesta, a minor planet, can be found close by.
So if you fancy taking a chance at observing Vesta, then wait until the sky is darker, so around 11:30, and locate Pollux and Gemini. Draw an imaginary line diagonally downwards to the left until you see a bright star called Kappa Geminorum in the left arm of Gemini, which points the way to Vesta, located further to the left.
At a magnitude of +8.3, you will need an optical aid to locate the asteroid. And again, you're going to need to know what you're looking for, because otherwise it's probably just going to look like, you know, a bright dot in the sky, like a star. Online resources will be a great help to locate this.
And we also have Comet 13P Olbers. So Comet 13P Olbers is to the right of Gemini this week, and the star Theta Geminorum points the way to this faint comet. But remember, the Sun sets later, and the nights are much shorter, so it will be tricky to spot. But, you know, give Vesta and Olbers a go.
And I quite like that this month, Gemini the twins, one hand is pointing towards Vesta and the other one of the twins is pointing towards Olbers. So I thought that was quite nice.
Ezzy: It's always nice when the constellations can point things out to you in the night sky.
Katrin: Yes.
Ezzy: They can have a handy little guide to you finding your way around.
Katrin: Yes, they're very useful to use, that's for sure.
Ezzy: Well, thank you very much for taking the time to take us through all of that, Katrin.
And if our listeners at home would like to get even more stargazing highlights and keep up to date with everything that's going on in the night sky, please subscribe to the podcast and we will see you back here next week.
But in the meantime, let's summarise this week again.
There'll be no planets in the night sky again, but the Moon is waning all week and will be at perigee on 2nd.
The moon is going to be 14% lit on 3rd, and at around 3:30am the crescent Moon and Mars will rise up in the east, which is a lovely pairing to see there.
On 5th, a very small crescent Moon will be located to the west northwest of Saturn.
And on 8th, a waxing crescent Moon lies within the of Gemini in the north west.
If you want to test your observational skills on the Moon, though, on night of the 8th and 9th, the Moon will be at favourable libration, so you'll be able to see the Humboldt crater on its rim. And while there aren't any planets in the night sky, there will be some in the morning sky or even the daytime sky.
On 4th, the conjunction between Mercury and Jupiter is going to occur in the daytime sky, with the closest separation happening at around 11:20 AM. So it's going to be very challenging to see, but hopefully you'll be able to get that.
You'll also find on that day that Comet A3 has moved out of the bowl of Virgo and is slowly making its way through the Leo.
Elsewhere in the Solar System, we have Vesta, a minor planet that's going to be located close to Gemini. Vesta is going to be at a magnitude of +8.3 so you will have to know what you're looking for to be able to find that one.
Also find that Comet C 2023 A3 Tsuchinshan-ATLAS has now moved out of Virgo whilst Comet 13P Olbers will be to the right of Gemini this week and the star Theta Geminorum points the way to this faint comet.
So lots of things to be getting on with in this week's night sky, as always, and hopefully we'll see you back here next week for even more stargazing tips.
Until then, 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 Louis 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 next week's episode – Star Diary: See the Lake of Death on the Moon (10 to 16 June 2024)
