Watch the shadows of Jupiter’s moons as they pass across the face of the planet. Get the details in the latest episode of our weekly stargazing guide podcast, Star Diary 5 to 11 February 2024.
Chris Bramley: Hello and welcome to Star Diary, the podcast from the makers of BBC Sky Night Magazine. You can subscribe to the print edition of the magazine by visiting skyatnightmagazine.com or to our digital edition by visiting 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 GMT. In this episode, we'll be covering the coming week from 5 to 11 February. I'm Ezzy Pearson and I'm joined this week by Paul Money.
Hello, Paul.
Paul Money: Hello, Ezzy hopefully we'll get some good views.
Ezzy: Hopefully. Do we have anything of particular note to look forward to this week?
Paul: Well, I'm afraid we have to start back in the twilight morning sky again. It's the way how things work, unfortunately, at the moment. But we start on the morning of 5 February and there we find the crescent Moon.
It's a thick crescent Moon. It's to the lower left of Antares as morning twilight begins. There'll also be Comet C 2021 S3 Pan STARRS. That's around a magnitude seven and a half.
But you might be able to spot it with binoculars and small telescope because the actual sky is a little bit darker.
So if you leave it until Venus is up, the sky will be bright. It'll be twilight. So try to catch it. Around about 6:00 to 6:30 in the morning. It's a little bit darker, but the Moon will be there. But, you know, you might be able to get it. And the Moon does form a bit of a triangle with Antares and the comet as well, sort of thing. So, you know, that gives you a bit of a guide roughly to where to look.
The comet will be to the upper left of the Moon, with the Antares to the upper right of the Moon as well.
So, you might also start seeing a little bit of Earthshine on the Moon as well. That's the light that's bounced off the Earth's atmosphere. It's like fill in flash. I always think of it as fill in flash. And it illuminates the night side gently.
But you start to notice it more and more as the phase gets thinner and thinner in the morning. And, of course, in the evening sky. as well.
Now February 7th, the crescent . Will have moved on. It'll be even slimmer by then. It'll be very low down. You want to be looking at about 7AM in the southeast, uncluttered horizon, so you get a view, because the Moon is a lot lower than Venus.
So you have to wait until Venus is up. The twilight doesn't get too bright, because it'll swamp the Moon and Venus, and we've also got Mars as well, so they form a bit of a triangle.
Now, Venus is under the Teaspoon asterism of Sagittarius, but I suspect the stars will be washed out by the twilight itself.
Mars may also be difficult as well because of the same reason, but it's worth trying for if you've got binoculars.
However, as we always say, don't leave it too long. The first hints of the Sun beginning to rise, stop observing with binoculars or even the naked eye because we don't want you to damage your eyes if you leave it too late.
But it's a nice view, and so the crescent Moon will be to the lower right of Venus, and then Mars is to the lower left. It gives you a rough idea of where to look. If you can see the Moon, Mars is just slightly higher above the horizon than the Moon, off to the left beyond Venus. So worth having a go at just in case.
Ezzy: And as you said there with the Sun, it's always when you're observing in the morning specifically, because in the evening, once the sun's gone down, it's gone down it's not coming back up again, but in the morning, make sure...
Paul: If it does, worry.
Ezzy: Yeah. If, if it comes up again, you have bigger problems. But in the morning, make sure you always look up exactly when in your area the Sun is going to rise.
Make sure you set an alarm and that you're fully aware because you don't want to catch the sun through optics. You can do yourself a lot of damage. So do be careful on that front.
Paul: Okay, all week, because the Moon's in the morning sky, this is your last chance to really grab the winter stars before the Moon comes back into the evening sky.
So as it happens, new Moon occurs on 9th, so, you know, the beginning of the week through to about the 8th, 9th, 10th, you can actually look at the evening winter constellations.
But I always think it's funny because it's actually an ideal time because if you're looking at, say 7 o'clock you've got the winter stars dominating, the constellations dominating, in the south.
So that's, it's winter at the moment, so that's understandable.
But ironically, you've got the autumn constellations over in the west, slowly beginning to set. And then over in the east, you've got the spring constellations rising.
So in the west, you've got sort of things like Pegasus, you've got Pisces, et cetera sort of beginning to set, sort of thing. Whereas you've then got Orion, Taurus, I mean, the really bright constellations, the really wonderful constellations of the winter sky.
I mean, okay, you've also got two planets, well, Jupiter and Uranus as well.
We've got the Milky Way, it's straddling the sky from Cygnus in the northwest, with Perseus right at the zenith, and then down to Sirius and Canis Major in the southeast as well. So really, this is the best chance this week to grab it. Let's hope you've got clear skies, because the photographers will be out. Imaging many of the nebulae, the Orion Nebula, and other, a lot of the fainter nebulas in this patch of the Milky Way.
I always think it's a bit sparser than the summer Milky Way, where there's lots and lots of nebulae to photograph. But there are a few, if you know where to look, sort of thing. And a lot of these star apps, you know, that's on your phone and on the computer, will actually show them quite well. Sometimes they show them too bright, and you think, oh, that looks bright, and then you go and try and image it and discover it's actually quite faint and needs a lot of exposure.
Ezzy: That is something you need to watch out for with those kinds of apps, is they're not always entirely truthful about how bright something will appear on your phone versus how it will appear in the night sky, or how colourful either.
Paul: Yes, they do tend to exaggerate the colour because it looks so bright, but really long exposures brings out the colour with these objects.
But, yeah, so this is a good week to actually do that before the Moon starts to really intrude.
Now, as it happens on the evening of 8th, we have another shadow transit. Again, it's Io sort of thing. Io transits followed by its shadow. You want to be looking around about evening twilight through to about 8pm in the evening.
So this is a lot earlier. So if you missed it last week, hey! You've got a second go. So it's always beautiful with these. They're forever going around Jupiter and there's going to be a point whereby they cross over the disc of the planet. So again, we have another go this time.
Ezzy: Some of those moons really whip around that thing in a matter of days. So if you miss it, it'll be along again in a minute.
Paul: Yeah. Io and Europa sort of thing, you know.
Ezzy: It's just a question of, is it going to be going across when it's up in the night sky and you can actually see it?
Paul: That's half the battle, isn't it? It's frustrating when... I found a few examples where Jupiter's just set and then the transits begin you think, no!
So take advantage of these if you've got a telescope. It's best to use a telescope for that, to actually view that. And of course, planetary images can capture them and the shadows can look quite dramatic. You know, this black blob on the face of Jupiter. And again, as we mentioned last week, if you do a series of animations, you can watch the moon pass across.
Now, the moons are brighter, so they tend to merge in more with the features of Jupiter, so you have to be careful you can spot it.
But the shadow is dark, so that's easy. You can watch the shadow marching across the disk itself and do an animation of that and send it into the magazine.
Ezzy: It's that sort of thing of, a lot of things in space tend to be kind of various shades of grey or brown, and that is kind of true for Jupiter and its moons, but the shadows are very, very dark and very distinctive.
Paul: Exactly.
Now, by the time we get to 11 February, the Moon is finally creeping out of the evening twilight. It'll still be a very slim crescent. Right even to about 6PM.
We're now finding Saturn is very low. I mean, the twilight's quite strong. Saturn is setting quite quickly. The slim crescent Moon will lie to the upper left of Saturn.
And it's a good time to look again for that Earthshine. It'll be quite prominent. So it'll be quite pretty in actual fact to see. Meanwhile, Neptune lies to the upper left of the Moon
. And it too will soon be gone from easy viewing. Especially as it's much fainter than Saturn.
We are in the last sort of like, I think, really week of getting Saturn and then, well, probably a week or so left of Neptune. It's running out of time. So let's hope we have clear skies to actually view that.
And would you believe it? It's a shorter week, this is a way how it works sometimes, isn't it? That you get times when there aren't as many events actually taking place.
But we end with another shadow transit of Ganymede. And there's only Ganymede's shadow crossing the hemisphere of Jupiter. This is a little bit later on sort of thing. We want to be looking from about 10:30PM until the planet sets and the planet will be setting roughly midnight-ish. So, you know, we are getting, again, the fact that Jupiter's now setting now, around about midnight. Shows you that it's only got a few more months left before we'll actually lose it.
But yeah, we've got the shadow of Ganymede crossing the disk of Jupiter. Again, it's at the tilt of Jupiter is such that at the moment. You know, Io and Europa can cross the main part of the disk quite prominently. But Ganymede is crossing the lower part of the southern hemisphere of Jupiter.
And Callisto misses completely. So its shadow is not crossing the disk of Jupiter. But we will have one in another week or so. Something to look forward to. But there we are. That's all the events for this particular week.
Ezzy: And thank you for taking us through all of those, Paul. It certainly sounds like we've got a lot coming up this week. If our listeners at home want to find out what's coming up in future weeks, do subscribe to the podcast to keep up to date with all of the latest stargazing highlights.
To go back over those again, on 5 February in the morning twilight, the crescent Moon is going to be to the lower left of Antares. And Comet C2021 S3 Pan STARRS may still be visible in the night sky.
On 7 February, Venus and Mars are going to be in the morning twilight. They might be quite difficult to see at that time so do be careful when watching out for them as well because the Sun might rise on you so make sure you're always looking nice and safely.
On 8 February it's a great opportunity to look at the winter constellations as the Moon is going to be new on 9 February.
It's also a great opportunity to catch the Milky Way this week as it will be arcing right the way across the night sky.
On 8 February as well we will also be able to see a transit of Io across Jupiter followed by its shadow and that will be in the evening twilight.
And then on 11 February it will be a great opportunity to catch Saturn in the evening twilight as well.
And also another shadow transit at Jupiter courtesy of the moon Ganymede in the evening.
So lots of things to be getting on with. Hopefully you'll find something in there that'll pique your interest, and we'll see you back here next week.
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. For more of our podcasts visit our website at skyatnightmagazine.com or head to aCast, iTunes or Spotify.
