What's in the night sky in the week of 1 to 7 May, 2023 in our weekly stargazing guide. Venus passes between the horns of Taurus, and it's a great time to observe the double star Porrima.


Chris Bramley Hello and welcome to Star Diary, the podcast from the makers of BBC Sky at Night Magazine. You can subscribe to the print edition of the magazine by visiting www.skyatnightmagazine.com or digital edition by visiting on iTunes or Google Play.

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 1 to 7 May. I'm Ezzy Pearson, the magazine's features editor, and I'm joined on the podcast today by our reviews editor Paul Money. Hello, Paul.

Paul Hello there. Looking forward to this week. Lots happening in the sky.

Ezzy Oh, that's great to hear. So what is going on in this week's night sky? Tell me more.

Paul Well, we can't avoid it. But you know, Venus, it really does dominate. And will do, I have to say, for several more months, which is good if you like Venus. And it is a brilliant evening star at the moment. On the first, it actually lies between the horns of Taurus. So the two stars that mark the horns. It's a little bit close to the one that's part of Auriga, Elnath, but it's still near enough on a line with them. So, you know, it's one of those things that the twilight you should be able to pick them out and allow it to sort of get dark. So, although its tarted about9:30 when twilight's still up. Search around like north western horizon towards Venus and see if you can still see the Pleiades. They struggling. they're almost at that point of disappearing and we mentioned them last week. And the thing about this week is that this could be the week we lose them completely until July, August. So, you know, that's they'll move that into the morning sky. So everything that drops into the evening twilight and disappears into the glare of the Sun, re-emerges in the morning several months later usually. So we've got Venus dominating as always around about -4.0, -4.3. So pretty bright. And it's one of those things that again, if you've got a really dark hori... it's worth trying this. You could try if you've got no light around, you know, light pollution. And once it gets dark and Venus is still you see if you can see your shadow cast by Venus. Pete Lawrence did it. I've only seen it once. Because I've got a lot of light pollution. So you have to get away from the light pollution. So there's no other source of light. So You've got to let Twilight finish so that it is a dark sky, but then.... The only problem at the moment is we've got the Moon up. so of course, the moon will cause problems. You've got to do this when there's no Moon. But it's something to think about that Venus casts enough light to actually cast a shadow. Pete Lawrence did a great one some years ago, he actually managed to do a photograph and did a did a series of for us on how to do that, which I thought was absolutely brilliant because I wouldn't have thought about doing that. Until he did that I didn't even realise it was bright enough to cast a shadow. So there you are.

Ezzy I've heard about people, you know, the Moon light is enough to some people can even read by it. It's so bright sometimes if it's a full moon. But I hadn't heard of Venus casting a shadow, so that is very interesting.

Paul It is. Say, well, we'll probably come back to this when we've got that moon out of the way because it is well worth it as such being a few weeks time. Now, in the meantime, of course, it is moving through Taurus and it will actually end up in Gemini. So it is moving rapidly through the constellation. But this is partly because of Venus's own motion and partly because, of course, the Earth's motion around the Sun is making those constellations sink lower and lower into the twilight. But we've also got Mars higher up. It forms a bit of a sort like triangle with Castor and Pollux sort of thing. But from our viewpoint, from the horizon, directly looking west, about 9:30 Mars looks as if he's directly below Pollux. So, you know, is that Pollux is the yellowish star of the pair. Castor is very white. And of course, he's a very tight double star as well. So another one well worth having a look at. But Mars keeps ahead of Venus. They don't get close together until late summer. And even then they don't get a really close conjunction. But because of the way out of the Solar System, the mechanics of the Solar System works. Venus will drop back before it actually encounters Mars, but they will get reasonably close. But that will be summer time. So Mars is keeping ahead of Venus. Its like, sort of, "chased me chase me! you won't catch me yet" sort of thing and Venus won't catch it just yet. So that was 1 May. 2 May, Let's go back to the moon, because I always like it when it guides us to certain stars. And on the actual 2nd is quite close just to the right of Porrima Gamma Virginis which is a very tight double star. Well worth having a look at if you've got a telescope. In fact, there are years when that is so tight you can't separate them. Hmm. So we're in a period at the moment where we can actually split them. So this is the time to see it as a true binary star. I always find that fascinating that there are some stars, that their motion is enough, that we actually get to see it and observe them getting wider and then closing up again. So we've seen two stars actually orbit each other. Most things are fairly stationary in the sky, in the sky when it comes to the stars.

Ezzy It's one of the reasons why I quite like the planets is because you can see that the entire universe isn't static. It's everything's in motion. It's just very, very slow. Well, it's not very slow. It's actually incredibly fast. It's just very, very big. And so we can't usually see these kinds of motions. But the fact that, you know, there are things out there, you know, people have been tracking expanding supernova remnants and things like that. There are times when you can see the fact that everything within the cosmos is actually moving.

Paul Yes, it's fascinating. I mean, you think of Barnard's star. You know, if you take photographs ten years apart, you completely see the motion, as I think you know. So it's one of those projects I kept promising myself, and I've never done it. I really should kick myself, really should do it. So back to the Moon, then. So we've got it going past Porrima on the second now, when he's quite close to Porrima, it does mean that the next night there's a good chance it'll be above or close to 'Speaker' or Spica in Virgo. And it is the brightest star in actual system and it's alpha Virginis sort of thing. So it's the brightest star technically in the constellation of Virgo, but the moon is beginning to get fuller. It's a gibbous phase now is heading towards full. So of course there's a lot of light there. So a lot of the fainter background stars, the galaxies in Virgo suddenly will be washed out as well. So this is why it's best to observe the moon. Have a look at some of the details on the moon itself. Now, as it is, sadly, I couldn't exactly find a decent event for 4 May, so I can't say May the force be with you.

Ezzy Oh dear.

Paul Oh I just did. Sorry for that is terrible isn't it. I mean, it's funny how these things fall down and get into local astro folklore sort of thing, but there are. So we'll jump to 5 May. We've actually got the moon again still. We're still in the evening sky. We're looking at about an hour later now, about almost ten, and it's directly below Alpha libra now for Libra, is that really is a tongue twister really? Zubinelgenubi. But it actually means Southern Claw because he is a throwback to when it was actually originally part of the constellation of Scorpius. It was the clause of the Scorpion until it was decided that it was dom... It was dominated... There was enough bright stars to make it stand out on its own. So it became the scales of justice, Libra instead. So there we are. But the names of the stars have the throwback to when that constellation was part of Scorpius instead. And Zubinelgenubi is a wide double star. I see. Binoculars sort of thing. So. Well worth having to look at again. So I would say it's always good to use the Moon as a guide to some of these stars, because often they're not just single. They may well actually be double as well. Then we get to 6 May and one following the moon still and from Libra it does go into Scorpius. But before we get there, there's a problem because full Moon occurs on 6 May. Now, why do you think that's a problem? Well, that's also the peak of the Eta Aquarid meteor shower, and I am absolutely sure they'll be media, "stunning meteor display tonight on 6th," completely ignoring the fact you've got a full moon and the full moon will wash it out. And that's the disappointment because a lot of people get excited, go out and don't see anything. And seasonal observers like ourselves know that generally don't bother.

Ezzy Yes, that is one of the kind of big dilemmas with meteor showers, because normally if there is the moon and it's it's not full full, there will be a couple of hours that you might be able to to get out there and see it, even if you can't see it for the whole night. But unfortunately, if there's a full moon, it usually means it rises at sunset and sets at sunrise. So it's going to be out for the whole night long. So you're not going to have much luck there. I also think the Eta Aquariids aren't one of the... more prolific showers they are. They don't have as high a ZHR, zenithal hourly rate, which you should always treat with a pinch of salt anyway.

Paul So yeah, well, the trouble is, is that the zenith hourly rate is literally under absolutely perfect conditions straight up. I think it was Pete Lawrence. It turned around and said that, you know, you literally you want to halve it and then you want to halve the number again. Yeah. And then you might get somewhere near.

Ezzy I will say we've not been particularly kind to this year's Eta Aquariids. There are some really good meteor showers coming up throughout the rest of the year. In fact, six meteor showers throughout the year will have the moon out of the way, including the two biggest ones, the Perseids in August and the Geminids in December. So keep an eye out for those. Make sure you subscribe to the Star Diary podcast and we will give you all of the details about those when they roll around. So perhaps give this one a miss, but do be aware there are some good meteor showers on the way.

Paul I mean, it's interesting. There are so many minor showers that most people don't even know about that we don't publicise because they're probably one or two meteors per hour and as we just mentioned, think that basically you'll have to be really dedicated to watch the sky for that.

Ezzy It's almost to the stage where you're probably just as likely to see a random meteor as you are to see one of these.

Paul Exactly, yes. And of course, the random ones can be anywhere across the sky, whereas, you know, if you can trace them back to the radiant, then you're you're a better chance that you're actually seeing a genuine meteor from that shower. But I've seen pictures where somebody said, "Oh, I've got a Perseid" and it's completely the wrong direction, wrong angle, little sort of thing. There's actually around about five showers on the go at that particular time. So, you know, they aren't just one shower. I think that's one of the things is that there are multiple showers and they build to a peak. And we always mention the peak because that's when you have the best chance to see them, don't you? But the actual showers usually have a build up and a drop back. So about a week or two beforehand they build up from 0 to the peak and then they drop back down. So you can see meteors either side of the peak. It's just that we tend to concentrate on that because that's when the general public have a better chance to see them, don't they? You know, we like to give them the best chance to actually see them.

Okay. So the moon is just past full on the seventh. So finally for this week, in the early hours. And yes, it has to be the early hours around about 2:30 in the morning, look towards the south. You've got Scorpius, actually, but you've actually got the moon in Scorpius as well. It lies directly below Delta and lies between Delta and Pi Scorpii. So they're best around about 2:30 in the morning and look towards the south and you'll also see the red Star Antares to the left of the moon as such. So the moon is to the right of Antares, Antares to the left of the moon. So therefore you can see that as well. And that sort of fits. It's nice. I mean, if you're a late night person, you know, it's well worth having a look at Southern and in the south, that's when it's at their best. Scorpius is at his highest for everything gets to its highest in the South. So technically, that's when we should observe them. But obviously events don't behave themselves normally, do they? Well, that's it Ezzy.

Ezzy Well, certainly a lot to be catching up with this week. To summarise on 1st we've got Venus will be right between the horns of Taurus the Bull. Plus it will also possibly be one of our last chances to see like the Pleiades this week. Mars will also be making a triangle with Castor and Pollux on the first, so keep an eye out for that. Then on 2nd to 3rd it's a great chance to take a look at the double star Porrima, where the two stars are quite far apart at the moment. So you should be able to see those clearly on the 5th. A full moon will be next to the double star, Zelbinelgenubi. Then on 6th, we have the Eta Aquariids meteor shower, but possibly wanting to give that one a miss as it will also be the full moon. Then on 7th the moon will be next to entries in Scorpius. So lots of things to catch up with this week. But thank you, Paul, for taking us through everything you can see in the night sky this week.

Paul It's a pleasure Ezzy.

Ezzy Pearson If you want to keep up to date with all of the latest stargazing highlights, do be sure to subscribe to the Star Diary podcast and we hope to see you all here next week. If you want to find out even more spectacular sites that will be gracing the night sky throughout the month, be sure to pick up a copy of BBC Sky at Night magazine. Well, we have a 16 page pull out Sky Guide with a full overview of everything worth looking out for. 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 a detailed star charts to help you track your way across the night sky. From all of us here at BBC Sky and Night Magazine. Goodbye.


Chris Bramley Thank you for listening to this episode of Star Diary, the podcast from the makers of BBC Sky at Night magazine. For more of our podcasts, visit our website at www.skyatnightmagazine.com or head to aCast, iTunes or Spotify.


Elizabeth Pearson
Ezzy PearsonScience journalist

Ezzy Pearson is the Features Editor of BBC Sky at Night Magazine. Her first book about the history of robotic planetary landers is out now from The History Press.