Challenge yourself to find the 1% crescent Moon as it passes by Jupiter and the Pleiades. Find out how to catch these and more stargazing highlights in this week’s podcast guide, Star Diary, 6 to 12 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 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 6 to 12 May. I'm Ezzy Pearson, and I'm joined this week by Mary McIntyre, an outreach astronomer and communicator.
Thank you, Mary. Hello and welcome back to the show.
Mary: Hi! It's great to be back again.
Ezzy: So, what have we got coming up for us in the sky this week?
Listen to last week's episode Star Diary 29 April to 5 May 2024
Mary: It's another poor week for the bright planets, but we can still see four asteroids. There are some lunar conjunctions, as always, a couple of lunar occultations that'll be a nice challenge, a couple of comets, and with the Moon out of the way, we can start enjoying the Bears and explore around that region of the sky.
So, starting off with the planets. Evening sky, no bright planets visible this week at all, which is really sad. They will be back!
But evening sky at the moment, we're having to make do with three asteroids. We have Pallas at mag +9.0, almost to opposition, so that is pretty much visible all night long in Hercules.
We have Juno at mag +10.0, lying below Leo after sunset, and that remains visible until about 3:40 in the morning. And then Vesta, mag +8.3, that is moving through Gemini and sets at about 1:30 in the morning. So you will need optical aids to see those, they're not particularly bright, but you can see them with binoculars, it will help you to familiarise yourself with the star field and track the asteroid's movement through the star field over time.
They're a great photo opportunity, a great sketching opportunity, and just the good for learning the star field through binoculars actually. I think they're quite educational in that regard.
In the morning sky, we can get a glimpse of Saturn and Mars. They're both around about mag +1.1. Saturn is in Aquarius, rising at about 4:00 in the morning, and Mars is in Pisces, rising about 15 minutes later.
Both of those rising in the east. They're going to be in the dawn twilight, so do be careful observing them. But you might just catch a glimpse of them.
Also, another asteroid is Ceres, that is mag +8.4 and that is to the left of The Teapot now and that is rising at about 2:00 o'clock in the morning. So nothing overly bright in the morning sky either, but there are still a couple of things to have a look for.
Ezzy: So even when the planets aren't necessarily behaving, there's still a lot of interesting things going on in our Solar System.
Mary: There are. I think Solar System mechanics themselves are quite interesting and when you actually think about where the planets have disappeared to and when they come back, whether it's a superior conjunction or inferior conjunction, it's actually a really interesting bit of science to kind of study the movement of the Solar System bodies.
So I forgive them for not being there for a couple of weeks.
Ezzy: If they don't go away, how can you miss them and enjoy them when they come back?
Mary: Exactly. We would take them for granted if they were there every night.
Moving on to the Moon and some lunar conjunctions. The Moon phase this week, we're heading towards a new Moon, which is happening on 8 May, so it's a really good time to kind of have a look at the southern hemisphere craters of the Moon when we have the waxing crescent Moon towards the end of the week.
Also looking for Earthshine when we have a thin crescent Moon is beautiful, you can sometimes see it with the naked eye, and that is the phenomenon of where the light from the Earth gets reflected back off the non-illuminated side of the Moon. So you get the crescent Moon, which is nice and bright, and then you get that gently illuminated surface, which always has a kind of bluish hue to it.
I think it's gorgeous. I love it on photographs. I love it through binoculars. I love drawing it. It's really nice.
So a waxing crescent Moon's a really good time to look for that.
On 8 May, around sunset, this one is a real challenge. A less than 1% crescent Moon is going to be 1º from Jupiter, so they're both going to be about 2º, just under 3º away from the Pleiades.
I have never seen a Moon that is that slender. I've tried, and so you're going to need a really low horizon to see a 1% crescent Moon.
Ezzy: Usually you're using the moon help direct you towards where things are in the night sky, like where is Jupiter, where is the Pleiades. In this case, you're going to be using Jupiter and the Pleiades to try and find the moon, which that alone amuses me.
Mary: Yeah, I mean even like a 4 or 5% crescent Moon in full daylight is hard to spot. It's only when we get to twilight that it stands out. I remember photographing an airplane once and suddenly realizing it had almost flown past a crescent Moon that I hadn't even noticed. So yeah, that one really will be a challenge, but you know, it's good to push yourself and do things that are difficult sometimes.
Slightly easier is the 5% waxing crescent Moon, which is going to occult a star. So that is when the Moon actually passes in front of the star. So it's a mag +8.3 star.
So this is something you're going to have to use binoculars or a telescope to observe, but because the Moon is moving at a different rate from the star field, the Moon moves relative to the stars.
And that means that you very often do get the Moon blocking out the light from the star.
That is going to disappear behind the top left side of the Moon, the non-illuminated side. As you look at the Moon, you may or may not see Earthshine, but the star will just disappear behind the disc of the Moon that isn't illuminated.
So, that is going to set before the star emerges again, but it's always fun to look at these occultations. I think they're awesome to observe.
Ezzy: Just watching a sort of star wink out of existence, just as something passes in front of it.
Mary: Yeah, and it really gives you that sense of Solar System dynamics and the fact that the moon is moving at a different speed to everything else.
On 10 May, we get a glimpse of Crater Humboldt. This is in the kind of western libration zone, which is because the Moon wobbles a little bit in its orbit, although it's always pointing its same face at us, we can actually see about 59% of the lunar surface, just not all at the same time.
And Humboldt is kind of in that libration area. It's a really interesting crater, it's got an amazing chain of central peaks in the middle of it. But when we observe it from Earth, it will look oval because it's getting foreshortened kind of left to right by its position on the Moon. Some time in lunar orbit you can't really see it because the libration is favouring the other side of the Moon, so if you do want to look for Humboldt, now is the time to do it, 10 May.
It's all happening on 10 May, actually. There's loads happening that night.
Ezzy: Yeah, I think with the libration features as well, because now we have things like the Lunar Reconnaissance Orbiter, and we've got these very detailed maps of the entirety of the Moon. And then you see sort of what it looks like from Earth, and then you see what it looks like from above, and it really just sort of brings home like how much of an effect that does actually have, the fact that you're seeing it on this sphere curving away from us.
Mary: It's interesting, I think there are only about four, possibly a couple more, genuinely oval shaped craters. All of the other craters we see that are oval are only looking like that because of the foreshortening because of their position on the Moon. And it's really interesting. I've done that myself, photographed J. Herschel, which is in the libration zone and then seen a Lunar Reconnaissance Orbiter picture.
And it's like mind blowing how different they look.
Ezzy: Nature likes things to be circles. So most things are circles. Though that, to be fair, that was how a lot of astronomers got themselves into trouble in ancient history of trying to make everything move in circles when it doesn't. But in terms of craters, they prefer circles.
Mary: They do, yeah. It takes, even like really big impacts at an angle will still make a circular crater. So it's something that I did a DIY astronomy article for the magazine that is online where you can actually just lob different sized things on a bowl of flour with cocoa powder on top and actually make your own impacts.
And it's really good fun to do. Yeah.
Ezzy: I did that as my A level science project in my physics class.
Mary: It's the most fun weekend I've ever had when I did that project.
Ezzy: I did. And I will put a link to Mary's guide – not my coursework because it was terrible – but I will put a link down in the show notes below.
Mary: So on the same night that you can see Humboldt, if you look at the Moon at 10:00PM it will be a 9.3% waxing crescent Moon, that is going to be just under 3º to the left of Elnath, which is Beta Tauri. And then later on, like an hour and a quarter later, the Moon will be ever so slightly more illuminated, and that is going to do another occultation, this time of a mag +7.45 star, Sigma 770. So it will disappear again behind the top left illuminated side of the Moon. And then if you keep watching it, it will then reappear again just over half an hour later. The exact time of the star disappearing and re-emerging will vary depending on where you are in the country. But although it's not like a naked eye visible star, through binoculars they are really good fun to observe.
So yeah, a lot happening on 10 May, but also on 11 May, if you look at the Moon at 11:30, it will be a 17% crescent Moon and it's going to be 4.5º away from Vesta. So a good way to find each other is when they lie quite close together. And finally, on 12 May at 9:45, the almost 25% waxing Moon is going to be just over 2º below Pollux in Gemini.
Ezzy: Moon's getting around this week.
Mary: Yeah, it's kind of quite high on the ecliptic, isn't it? So it's kind of passing through lots of interesting things, which is good. It gives us stuff to observe, even when we don't have that much darkness now already.
Ezzy: Exactly.
Mary: A couple of comets to mention. We have Comet Olbers moving through Taurus and heading towards Auriga. That is going to be visible at about 10:30, 10º above the horizon. So not particularly high.
That is around about mag +9.0, but it is brightening and will reach peak brightness on 1 July.
C/2021 S3 PanSTARRS is faded even more. It's now probably going to be around about mag +11.5, so that is going to be more of a challenge. But if you do want to look for that, it's moving through Cygnus and should still be a telescope object and certainly a photographic target if you are into astrophotography.
So finally, I want to talk about the bears, the Little Bear and the Big Bear, or Ursa Minor and Ursa Major. We have a new Moon this week, so it's a really good opportunity to scan around.
Ursa Major is really high at the moment. Really high near the zenith actually, so it's a really good time to have a look at some of the many galaxies that reside in it, but also Ursa Minor as well.
There's stars of Ursa Minor are quite faint, so for many people they don't get to see Ursa Minor in its entirety, so the only time to really catch a glimpse of the stars of Minor is actually during the new Moon.
There are so many galaxies in this area around there, around Coma Berenices and just that whole region, but a couple that are worth kind of pointing out in Ursa Major.
First of all, Bode's Galaxy M81, that is a barred spiral galaxy.
Now we're going to give you magnitude values here, but it's worth remembering that is not the magnitude they appear because galaxies have a very low surface brightness. So although Bode's Galaxy is technically mag +6.9, In reality that brightness is spread out over a certain area so it is going to be more faint than that and it will just be a little smudge.
Ezzy: Yeah, if you take it all together, they're pretty bright. But it's that bright is smeared out and that's why you do need to have, you know, optical help and usually using adverted vision as well to be able to see these things.
Mary: Well, Bode's Galaxy is great because there are two galaxies that are kind of very close together.
So we've got M81, which is Bode's Galaxy, which is absolutely beautiful spiral galaxy that we're looking down on essentially, so you can really see the spiral arms. That is about 10º to the lower right of Duhbe, which is one of the stars of the bowl in The Plough.
Near that is M82 which is actually a starburst galaxy. It's sometimes called the cigar galaxy because it's kind of long and thin. So the different morphology between those two galaxies is really stark and it stands out really well on photographs. I remember photographing a supernova in M82 a couple of years... well a long time ago now it will be. Time moves so fast.
I think it was around 2014ish, there was a supernova in M82 and I photographed it with just a single shot and like the morphology of the galaxy just popped out at you. So those two galaxies are really nice. So they kind of make a triangle with the tail star of Draco, Giausar, so you can kind of use Duhbe and the tail star of Draco as finders to help you locate those galaxies.
If you find the tail star of The Plough which is standing straight upwards at this time of year, the very end star of the handle of The Plough is Alkaid and you can use that to help you locate M101, the Pinwheel Galaxy. That is mag +7.9 but again will have a low surface brightness and that is about 5.5º to the right of Alkaid. So you can use Alkaid as a really good starting point for a few of these galaxies actually. So that one's to the right, but if you go to the left of Alkaid 3.5º, you'll find M51, the Whirlpool Galaxy, probably my favorite galaxy. It's just so beautiful.
And that is one that you can see with binoculars. If you let your eyes get dark adapted, if you know where you're looking, if you use averted vision and all of those tricks, it is a really decent sized galaxy. So it's a mag +8.0 galaxy, but it is doable with binoculars.
Ezzy: Yeah. And it's also because both the Whirlpool and the Pinwheel Galaxy, you're, you're pretty much looking at them head on.
So we're looking at them sort of... if you think of it as a disc, you're looking straight at the disc of it rather than at the side in any way. So they are particularly... you can see all of the lovely spiral arms in them.
Mary: They're so, so beautiful. And if you go nine degrees left of Alkaid, you'll come across the Sunflower Galaxy, M63.
So that is also a spiral galaxy, but the arms are kind of tighter packed and it's sometimes referred to as the Sunflower. A lot of the time I don't think they look anything like the names they're given, but there's that one. But if you find M63, the Sunflower Galaxy, you can then look 5º to the lower left of that to find the Croc's Eye or the Cat's Eye Galaxy.
Some of these are now heading really probably towards photographic targets, but there are just so many galaxies to choose from there. And one other galaxy to talk about is M106, which is a spiral galaxy, but this one's tilted, so the angle we're looking at it is very different from those other open spirals.
And that is about 10º left of Alioth in The Plough, and that's about 11.5º below M63. So with all of these objects, you can kind of use them for like galaxy hopping almost. Find one, skip to here, then skip to the next one, and just take your time in that area. There is so much to look at around Ursa Major.
The whole constellation itself is just full of stars.
There are so many stars in that part of the sky, and it's kind of almost difficult to know which deep sky object you're looking at rather than finding them, because there are just so many that you can land on around there.
Now Ursa Minor, there is a giant A class star within Ursa Minor, that is Pherkad.
It is one of the brighter two stars of the bowl of Ursa Minor. That is 15 times larger and 100 times more luminous than our Sun and is rotating really quickly, about 180 km/s. That is a variable star, and its magnitude only varies by about a tenth of its overall magnitude, but it does so every few hours.
So that's a fun one to try to see if you can spot the difference in magnitude over time. And we don't actually know why that star varies. There are theories, but we don't fully understand why that one is varying in brightness. So that's an interesting one to look at in Ursa Minor while the Moon is out of the way.
Ezzy: And if people would like some more ideas of how to tour around the various different galaxies in Ursa Major, we have some guides on how to do that over on our website, skyatnightmagazine.com. So if you want a bit of guidance about how to get around all of those, I'll put that in the show notes below.
Thank you very much for taking us through all of those, Mary. There's again, as always, lots of things to see in this week's night sky, as I'm sure there will be in next week's night sky, so do subscribe to the podcast to make sure you keep up to date with all of the latest goings on in the night sky.
But to summarise that week again, starting off with the planets, there won't be any good planets in the evening sky this week, but you can still see the asteroids, Pallas in Hercules, Juno in Leo, and Vesta in Gemini.
Moving into the morning sky though, we'll have Saturn in Aquarius and Mars in Pisces, as well as the asteroid Ceres, which will be in The Teapot asterism as well.
Looking at the Moon, the new Moon will be on 8 May, making this week a great time to look for Earthshine.
On 8 May, a 1% crescent Moon will appear near to Jupiter and the Pleiades. Quite tricky to see that one, but worth a look if you can.
On 9th, the Moon will occult star Hipparchus 21813.
On 10 May, Crater Humboldt, a libration feature, will be on view.
And also the crescent Moon will be next to the star Elnath, as well as occulting Sigma 770 as well. On 11th, the Moon will be near to Vesta, and on 12th, near to the star Pollux as well.
In terms of comets, we have 13P/Olbers, which is still in Taurus and moving towards Auriga, and S3 PanSTARRS is still just about with us this week. It's fading away in Cygnus, but still on show.
It's also a great time of the year to take a look at Ursa Major and Ursa Minor, the two constellations. There are lots of galaxies to see in Ursa Major and several variable stars as well in Ursa Minor, so lots of things to look for there.
So thank you very much for joining us this week and hopefully we'll find you back here next week as well. Goodbye!
If you want to find out even more spectacular sites 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, the 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 favourite podcast player.
