What's in the night sky in the week of 17 to 23 April, 2023 in our weekly stargazing guide. The Lyrids meteor shower peaks this week, and Venus approaches the Moon in the daylight sky.


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 Pearson 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 17 to 23 of April. I'm Ezzy Pearson, the magazine's features editor, and I'm here to take you through this week's stargazing highlights.

And our first event to look up for is on 18 April, where Venus is going to be just north of the Hyades open cluster. We spoke a little bit about the Hyades in last week's episode, so go back and listen to that if you'd like a bit more information. But it is an open cluster nearby to the Pleiades, and on the 18th of April, Venus is going to be just north of the Hyades and a very bright too, magnitude -4.0. So still very much the brightest thing in the night sky after the Moon. Its position on that date will also mean it's a very good photo opportunity. If you want to get a shot of Venus, the Hyades and the Pleiades all in together. So get your camera out if you fancy doing some wide-field deep sky astrophotography and getting those three together.

Moving forward onto 21 April. We have a trio of Solar System objects in the night sky, but they are going to be a bit tricky to catch. Mercury, Uranus and the Crescent Moon are all going to appear together in the west, northwestern sky just after sunset. However, they are going to be tricky to catch because Mercury is fading at the moment. It's only going to be +2.3 magnitude. And it's always fairly hard to see because it is so close to the Sun. So you have to wait for the Sun to go down until you can really see it properly. Uranus is also quite a difficult planet to catch. It's fairly dim. You definitely are going to need a pair of binoculars or a telescope if you're going to be trying to see it from the UK. But also this time the Moon is going to be quite hard to see because it's only 3% lit – a very thin crescent. You'll be able to see the three together on the west, north western sky. Uranus is going to be up and about until around about 9:45PM. Mercury sets around about the same time, but the sun sets is only at 8:15PM and if you want them high enough to say you are going to be looking in twilight when the sky is still fairly bright behind them. That's going to really wash out these dim objects. Even with a telescope or binoculars, you're probably going to struggle to see them. But if you fancy a challenge, they will be there. From Mercury, the Moon is going to be about 6.4 degrees away at this time. And Uranus, 3.8 degrees away. So look for those out on the west, northwestern sky, just after sunset on 21 April.

Moving on to the night of 22 to 23 April, and that is when we have the Lyrids meteor shower. The Lyrids run from 14 April, but they are going to reach their peak, their peak activity on 22 April that night, moving into the morning of 23rd. Meteor showers always happen at the same time every year and that's because they occur as we pass through the stream of dust and debris that's been left behind by a comet in most cases. And at the same time, every year, Earth's in the part of its orbit which passes through that stream and those pieces of dust hit Earth's atmosphere, going at incredible speeds. And that heats up the air around them, causing them to glow white hot. And that's what we see as a shooting star or a meteor. The best way to observe them is to find yourself a nice dark sky that you can access safely. Ideally, you want to be trying to get away from all sources of light that you can, but obviously that's not always possible, particularly if you live in the middle of a city. So really, if you can get somewhere where you can get away from direct sources of light shining. So even if it's just your in your back garden, but you're in that corner where there's no direct street lights shining on you that will help you if you can get away, maybe towards a park or a dark space somewhere nearby, that would be even better. But obviously always: safety comes first. So make sure that it is safe for you to be there and that you have permission to be there as well. So that's one of the best ways. Make sure you wrap up nice and warm. We don't want you getting cold because you might be out there for several hours. The best thing to do is to wait until it gets nice and dark when true dark has set in and then allow your eyes about 20 to 30 minutes to adjust to the dark and then look up at the night sky. Well, you can look up at the night sky whilst you're adjusting to the dark. But the more you allow your eyes to adjust to the dark, the more dim objects you will be able to see and the dimmer meteors as well. And hopefully you should begin to see these meteors beginning coming across the night sky. Now, the Lyrids isn't a particularly prolific shower. It has what's known as a Zenithal Hourly Rate or ZHR of about 18 per hour. However, that doesn't mean that you should expect to see 18 Lyrid meteor showers per hour because the ZHR is a perfect ideal rate that you would see under perfect conditions if it was perfectly placed in the sky and there was no light pollution. That obviously isn't the case. So the actual amount that you are going to see is considerably less than that, usually about a half or a quarter. So you're expecting to see one every 5 or 10 minutes or so. This isn't a particularly prolific shower. But one thing is going to be helping the visual hourly rate on this one, and that is that the Moon is out of the way. I said try to get away from all sources of light pollution that you can. The Moon is probably the biggest source of light pollution that you can't do anything about. But on 22 April, it's going to be pretty out of the way. It sets just before midnight. It's very thin at the moment, so it's not casting much light when it is up in the night sky and pretty easy to be able to just hide it behind a tree or a big bush or something, to be able to dim some of its bright light out of the sky. But it does mean if you are observing after midnight, it will be out of the way entirely. Now, whilst you're out observing, you might see a meteor that's not actually associated with the Lyrid meteor shower. You do quite often see shooting stars at any time of year. They can just come across the night sky. To know if you are seeing a Lyrid or a random meteor. You can trace the path where the meteor appears to have come from. And if it appears to be pointing towards the star of Vega, that bright star Vega, that means it's a Lyrid. Because the radiant – So the point where all of these meteors appear to come from – is in the constellation of Lyra, which is where the Lyrids get their name. I also recommend trying. Now, even though this isn't one of the best meteor showers throughout the year, I would recommend trying to get out there and observing this one because it is a palate cleanser or a taster for what's coming for the rest of the year. We have six meteor showers throughout the year where the Moon is going to be out of the way, including the two biggest ones throughout the year, which is the Perseids in August and the Geminids in December. If you want to hear more details about those meteor showers, then subscribe to Star Diary and we will tell you all of the details about how to catch those when the time rolls around.

But moving back to this week and 23 April. On that day, the moon and Venus are going to be separated by less than three degrees at around sunset. So the two are going to be passing nice and close to each other. The Moon at the time is going to be a 12% lit crescent, and it will be passing north of Venus, which is going to be a magnitude -4.0 At that time, if you'll remember. So a nice bright planet. In fact, it's so bright, you should be able to see both of these together in the daylight sky. Though they'll be three degrees at sunset. Their closest approach to each other is actually at 1:00 in the afternoon. So if you fancy a bit of a daytime observing of the planets in the moon, you could go about doing that. At 1:00 they'll be about 0.7 degrees apart from each other. You can see the two about 50 degrees above the east southeastern horizon. However, it is going to be in the middle of the day, which means you have to be wary of the Sun. Fortunately, the Sun is about 40 degrees away on the sky itself, which means it should be fairly easy to find somewhere where you can see the moon and Venus, but the Sun is behind a building or somewhere where it's not accidentally going to be caught by your optics. You do want to be careful because if you accidentally catch the Sun in a pair of binoculars or a telescope, you can do yourself permanent damage. Even looking with your naked eyes should always be avoided. But the easiest way to make sure you're going to do that is if you're standing in a shadow. If you're standing in a nice big shadow of a building, is probably your best bet, then you definitely know that there is no way the Sun is accidentally going to come into your optics. Just make sure you keep an eye on where the shadows are moving as you are doing your observing. If you want to be sure to be safe, though, you can always wait until the Sun has set. The two will have moved apart by then. They'll be three degrees apart and you'll be able to see those together until Venus sets at about quarter past midnight. So lots of opportunity to capture those two together.

So there's lots to see in the night sky this week, 18 April. Venus is going to be north of the Hyades. Then on 21st, Mercury, Uranus and the crescent moon will be together just after sunset. And finally, we finish up the week on 22 to 23 April, when we have the peak of the Lyrids meteor shower. 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.