What's in the night sky of the week of 12 to 18 December 2022 in our weekly stargazing guide.


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 to 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 GMT. In this episode will be covering the coming week from 12 to 18 December. I'm Ezzy Pearson, the magazine's features editor, and I'm joined on the podcast today by reviews editor Paul Money. Hello Paul.

Paul Money Hello there Ezzy! Well we had an exciting week last week, but it's not too bad this week as well. We've got some interesting things to look for.

Ezzy Oh, excellent. So what do we have coming up in this week's night sky?

Paul Well, a lot of them do occur in the late night, so we're talking about late evening into the early morning. But that's one of those things with astronomy and especially as we're following the Moon, we often follow the Moon when it's near various objects. Now on 12th it actually lies between or so, like on the boundaries of Cancer and Leo. But on 13th, on the late evening, it actually lies next to the Sickle asterism of Leo. I always think I would like to point out the asterisms because like The Great Bear, we don't... people look at the Great Bear and what they see is the Plough. The Plough is the asterism part. The Great Bear is the rest of the faint stars that make up the constellation, the Great Bear. But most people see the Plough and say, that's the great bear. The sword too, right? But it's an asterism. It's the brightest seven stars. The Sickle's the same. It's the it's a particular shape. It looks like a sickle or a scythe. And so you've got Regulus at the bottom of the umbrella is a sort of bright first magnitude star.

Ezzy So the difference for those who don't know an Asterism is a popular known star pattern, so things like the Plough, like the Sickle. I think also there's this ones... sort of various triangles and squares and things like that. Is it the Square of Pegasus?

Paul Square of Pegasus, yes. The Circlet of Pisces. Yeah.

Ezzy Yes. Which tend to be small subsections of larger constellations and constellations sort of mark out areas of the sky as well.

Paul So there we are sort of thing. So as I say, the Sickle is a quite prominent one. And, you know, there is quite a few stars in it that make it up, but the Moon will, over the course of that night, pass above Regulus but it's creeping ever closer in fact, to Eta Leonis. but before we go there, sort of thing, just a reminder to have a look at Regulus, because Regulus is a wide double star. Unequal components, the bright main star dominates, but there is a fainter component next to it. So well worth having a look at in binoculars. You can see that binoculars, so you don't need a big telescope for that. And then another one to look for is actually in the Sickle as well sort of thing. Further up the handle and slightly around the crookedness of the Sickle itself. We've got Algieba, Gamma Leonis. Very tight double, but two golden yellow stars is absolutely gorgeous in a telescope. One is just slightly fainter than the other. So they're two highlights. While you've got the Moon here guiding you. In actual fact, the Moon you could say he's forming a triangle with Regulus and Algieba. It just so happens that Eta lies between them as well, sort of thing for when its own little triangle. And watch during the course of the rest of the night because into the early hours of 14th the Moon glides past Eta. And again I was love it when they're so close the Moon is so close to a bright star and it really brings it home sort of thing. If you watch it gradually drifting past the stars, a bit like the occultations last week, you see the real motion of the Solar System. You see the real motion of the Moon itself. So if you start off the late evening and note the position of the Moon, wait until about, okay, yeah, I know... well we're astronomers, we will stay up. 5 a.m.. Yes, I know. It's a real time. You know, and if there's lots of things to look at in the night sky, not just the patches we spot on these recordings, but the Moon passes just under Eta Leonis itself at about 5AM. And if you watch over the course of say, about 10, 15 minutes, you can see the motion of the moon as it passes the star the star acts as a reference point, Ezzy. It appears to be the fixed point in the sky, whereas the Moon is the motion, it's the moving one. Now that morning is also, it could say, a best time to catch a falling star and put it in your pocket. But not literally, of course. It is the peak of the annual Geminids meteor shower, but there's a bit of a fly in the ointment and we've just mentioned it. Yes, the Moon's up. So the nearby Moon will spoil the actual view. It's one of those things that the peak actually occurs in the afternoon of 14th. So you really want to be looking around about late night 13th into the 14th. The radiant is close to the star Castor, obviously one of the twins in Gemini. But the point is, just bear in mind that the Moon will wash out the fainter meets, and you'll only act with the odd one or two that are particularly bright. But it's still worth having a go. And again, very similar thing to what we said last week about the Pleiades. It's worth seeing what you can see, because one of the things is we can sometimes put people off saying "Oh, the Moon light will wash it out" and so people don't bother. But it's worth having to check just to see what you can see of the Geminids under these conditions because it gives you a guide then and makes you excited for when you know there's no Moon next time. Because if you can see, say, four of five with the Moon up, then it gives you a greater chance of seeing a lot more when there's no Moon the next time the meteor shower comes around.

Ezzy I will say this year has been... I'm going to be honest, pretty pants when it comes to meteor showers. All of the major ones have been washed out for the Moon. But I have been taking a look forward to next year. And 2023... If you're into your meteor showers... you're going to want to be paying attention in 2023, I'll put it that way. So yeah, maybe get some practise in now if you can.

Paul Exactly, exactly. Because I mean next year, I mean I've been doing the same and oh yes. You know, we have years where the meteor showers are really cold because of the Moon. Then we have the years that you look forward to when you got a whole range of meteor shower and you've got a chance to see them against dark skies. So yes, yes. Get excited for that and get practising now watching out for them. Okay. Now, the next period, December 16 to 18, I'm afraid. Yes. We're still with the Moon because we with the Moon. It's got to be in the early morning sky. We're looking about 6AM. Now. The Moon actually does take quite a bit of time, several days, in fact, to cross one of the largest constellations in the night sky. It's not the largest, but Virgo is huge and it actually takes around about four days. But one of our days falls into the next week, so we won't... Discount that won't we, we'll just deal with the three, but it's still amazing that the Moon's going to pass through Virgo over the next three days sort of thing. That's how big the constellation is. And as it does so, again, it's fairly close to some reasonable stars, but the phase is thinning. It's getting less, it's waning towards the new Moon. So the phase is getting less and less. We're seeing a crescent Moon build up. So as it moves through Virgo on 16, the Moon rises to the right of New Virginis. That's on the 16. So the thick crescent there. Then the next morning is actually quite close to Eta Virginis. I think that's called Zaniah, if I remember right. And but we usually say Eta Virginis as such but he's also to the upper right of the close double star Gamma Virginis or Porrima. Now Porrima has been opening up over the last few years. There are years when it is so tight, amateur telescopes can't resolve it, but it is wide now. So this is a time to actually observe Porrima. You've got a guide there, you've got the Moon guiding you towards Porrima. Then finally on December 18 the crescent Moon will lie to the upper right of Spica and Alpha Virginis the brightest star in the constellation. That's why it's called Alpha. We use the Greek designations as a rule to go from the brightest alpha to the faintest omega. But as we know, Ezzy, there are a few exceptions out there. Whether they got there, they hadn't gone to a particular brand of spectacle makers.

Ezzy Well, I think it was also, you know, some stars, they do their brightness does change sometimes. Sometimes it's, you know, somebody's telescope... It could be, you know, where you are in the world. And also most of these, when they were given their names, a lot of them were just done by eyeballing it, essentially, and trying to work out which one they thought was the brightest. So it's know it's entirely possible that they might have been mistaken on a couple of them.

Paul And when we think about it, I mean, you know, only just a couple of years ago, we had Betelgeuse go through a dramatic dimming naked eye.

Ezzy Exactly.

Paul You know, so perhaps, you know, when they when they labelled it sort of thing, you know, then it may have been dim. It may have been bright. But we never know, do we? We need a TARDIS, we go back and see what they really saw.

Ezzy And what they were really called. How you pronounce the names.

Paul Exactly. Yes. However, the other thing to note is you start to see Earthshine. As the crescent gets thinner, the Earthshine, which is the light bounce from the Earth back onto the Moon, fills in the night side. So you feebly see the features and I think it just looks ephemeral. It looks gorgeous when you see this crescent and this ghostly view of the rest of the Moon hanging there as well. So there we are. That's we. We get the week finishing and we finish with a crescent Moon, Earthshine and Spica, depending on how you want to pronounce it.

Ezzy So thank you very much for taking us through that week, Paul. It certainly sounds like there's a lot of things to capture people's attention. There's things most days. So on 12th you've got the waning moon passing through the circle of Leo on 13th to 14th that night there's going to be the peak of the Geminids meteor shower. Then on the 14th the Moon will pass by the bright star Eta Leonis. On the 16th, the Moon is going past Gamma Virginia or Porrima, and then finally on the 18th Alpha Virginis. So lots of times chances to see the Moon passing by some really bright and interesting stars. Thank you very much for taking your time to talk to us about that, Paul. If our listeners want to make sure that they don't miss any of the upcoming spectacular stargazing events, please do subscribe to the Star Diary podcast to keep your weekly update 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. Where, 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. Ask guide has got you covered with the 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 the Star Diary 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.