0:00:02 > 0:00:07THEME MUSIC: "At The Castle Gate" from "Pelleas and Melisande Suite" by Jean Sibelius.
0:00:25 > 0:00:27Welcome to the Royal Observatory Greenwich,
0:00:27 > 0:00:30the historical home of British astronomy
0:00:30 > 0:00:33and a place with a surprising link to this month's topic.
0:00:33 > 0:00:35The big story at the moment in our night skies,
0:00:35 > 0:00:38is the fifth planet of the solar system, the mighty Jupiter.
0:00:38 > 0:00:41And that's what we're going to explore in this programme.
0:00:41 > 0:00:45Coming up, physicist Helen Czerski will be trying to uncover
0:00:45 > 0:00:48some of the mysteries of Jupiter's atmosphere.
0:00:48 > 0:00:50The memorable thing about the Great Red Spot
0:00:50 > 0:00:51is it's been there for so long.
0:00:51 > 0:00:54These features will persist for as long as the experiment runs.
0:00:54 > 0:00:56Pete Lawrence will be showing us
0:00:56 > 0:01:01just how easy it is for anyone to get a great view of Jupiter.
0:01:01 > 0:01:04We'll be finding out about an astonishing new discovery,
0:01:04 > 0:01:08water spraying out from one of Jupiter's moons.
0:01:08 > 0:01:12We're talking about a plume of water 200km high
0:01:12 > 0:01:13over the south pole of Europa.
0:01:13 > 0:01:15And how the pictures you take
0:01:15 > 0:01:19could be an essential tool in the study of the gas giant.
0:01:22 > 0:01:25Jupiter is always a wonderful object to see in the night sky
0:01:25 > 0:01:28but right now it's truly spectacular, outshining
0:01:28 > 0:01:30even the brightest stars.
0:01:30 > 0:01:34For the next few months, it'll be high in the sky after sunset
0:01:34 > 0:01:37making this the best opportunity for British observers to get
0:01:37 > 0:01:39a look at this fascinating world.
0:01:39 > 0:01:43One of the joys of observing Jupiter is seeing those distinctive bands
0:01:43 > 0:01:45and, of course, the Red Spot.
0:01:45 > 0:01:47This image shows that in amazing detail.
0:01:47 > 0:01:49Now the bands are actually formed by
0:01:49 > 0:01:50a weather system which goes all
0:01:50 > 0:01:55the way round Jupiter, with wind speeds greater than 300mph.
0:01:55 > 0:01:58The Great Red Spot is actually three times the size of planet Earth
0:01:58 > 0:02:01and has been raging for over three centuries.
0:02:01 > 0:02:03And it's to this amazing weather that we turn first.
0:02:03 > 0:02:06We sent physicist Helen Czerski
0:02:06 > 0:02:09to see she could find out what causes this magnificent display.
0:02:15 > 0:02:18When you look at an image of Jupiter, the most obvious thing are these
0:02:18 > 0:02:22fabulous bands of colour that go horizontally across the surface.
0:02:22 > 0:02:25But Jupiter doesn't really have a surface as such
0:02:25 > 0:02:26because it's a gas giant.
0:02:26 > 0:02:32What you see on Jupiter are swirling clouds of many different gases,
0:02:32 > 0:02:34effectively what we're looking at
0:02:34 > 0:02:38are just the tops of complex weather patterns.
0:02:38 > 0:02:41But what drives this violent and long-lasting weather?
0:02:41 > 0:02:43You'd think that - you can see so much detail -
0:02:43 > 0:02:46the answer must be obvious but actually this is
0:02:46 > 0:02:48one of the biggest mysteries in the Solar System.
0:02:48 > 0:02:53One of the clearest features we can see from Earth is that
0:02:53 > 0:02:57the atmosphere is arranged in a series of bands circling the planet.
0:02:57 > 0:02:59These bands are iconic,
0:02:59 > 0:03:02really strongly associated with Jupiter,
0:03:02 > 0:03:07but this isn't the only planet to have weather in bands like this.
0:03:07 > 0:03:11Saturn has clearly defined stripes of light and shade.
0:03:11 > 0:03:15Neptune also has subtle visible bands.
0:03:16 > 0:03:18The bands of weather that we are most familiar with
0:03:18 > 0:03:21are actually here on Earth, it's just that we can't see them
0:03:21 > 0:03:23because our atmosphere is transparent.
0:03:23 > 0:03:26But they are there.
0:03:26 > 0:03:29Earth's atmosphere is actually divided into distinct regions
0:03:29 > 0:03:31known as cells.
0:03:31 > 0:03:35Each cell is driven by hot air rising high into the atmosphere
0:03:35 > 0:03:38and flowing either north or south.
0:03:38 > 0:03:39There are six in total.
0:03:41 > 0:03:43And the thing that I like about the comparison between Earth
0:03:43 > 0:03:49and Jupiter is that we can't see those bands, those cells,
0:03:49 > 0:03:53on Earth, but on Jupiter they are really visible.
0:03:54 > 0:03:59Jupiter has many more cells than we have on Earth, there are at least 12.
0:04:00 > 0:04:04And that's not just because it's bigger, the number of cells
0:04:04 > 0:04:07a planet has actually depends on how quickly it's rotating.
0:04:09 > 0:04:14Earth rotates once every 24 hours, that's what defines a day.
0:04:14 > 0:04:18But Jupiter rotates roughly once every 10 hours, over twice as fast,
0:04:18 > 0:04:22and if Earth did the same, our weather would be very different.
0:04:24 > 0:04:26This is a simulation of the Earth as it is now,
0:04:26 > 0:04:29looking slightly down from the northern hemisphere.
0:04:29 > 0:04:32So the planet is rotating this way around.
0:04:32 > 0:04:36What the colours represent are wind speeds high up in the atmosphere.
0:04:36 > 0:04:40But if we change the simulation, so we speed up the rotation speed of the
0:04:40 > 0:04:45Earth by a factor of four, a six-hour day, this is what it looks like.
0:04:45 > 0:04:48You can see that suddenly there are many more bands
0:04:48 > 0:04:50stretching around the planet.
0:04:50 > 0:04:53The winds are constantly being pulled in a lateral direction, and that
0:04:53 > 0:04:57means it's really hard for currents from the north and the south to form.
0:04:57 > 0:05:00So the structure of Jupiter's atmosphere
0:05:00 > 0:05:05is locked in these bands that we're all so familiar with.
0:05:05 > 0:05:08The bands of fast-moving winds aren't the only
0:05:08 > 0:05:10weather we can see on Jupiter,
0:05:10 > 0:05:13there are also extraordinary vortices and spots,
0:05:13 > 0:05:16some of which last for centuries.
0:05:17 > 0:05:21But why did these atmospheric storms last so long?
0:05:22 > 0:05:26I'm meeting Professor Peter Read, who is using a jug of water,
0:05:26 > 0:05:27some sparkling dye
0:05:27 > 0:05:32and a rotating rig to recreate a section of Jupiter's atmosphere.
0:05:32 > 0:05:35Jupiter is quite unlike the Earth in many respects.
0:05:35 > 0:05:37And in one important respect,
0:05:37 > 0:05:39and that is that on the Earth, the equator is usually hot
0:05:39 > 0:05:42and the poles are cold,
0:05:42 > 0:05:44on Jupiter that's not the case.
0:05:44 > 0:05:47What we tend to see is that the main temperature differences that we can
0:05:47 > 0:05:50measure in the atmosphere are actually between the bright bands
0:05:50 > 0:05:52and the dark bands. You will typically have
0:05:52 > 0:05:54a bright band, which is relatively warm,
0:05:54 > 0:05:56and then, to the north and the south of that,
0:05:56 > 0:05:59there will be a dark band that is relatively cold.
0:05:59 > 0:06:02That sounds amazing to me because I'm used to thinking about the Earth,
0:06:02 > 0:06:05and the idea that the equator is hotter and the poles are cooler
0:06:05 > 0:06:07is such a strong idea and that drives
0:06:07 > 0:06:10all of our weather on this planet, but Jupiter is quite different.
0:06:10 > 0:06:13And Jupiter has an extra ingredient that the Earth doesn't have and that
0:06:13 > 0:06:18is that Jupiter itself is a source of energy from its deep interior.
0:06:18 > 0:06:22It actually generates almost as much energy from
0:06:22 > 0:06:24its deep interior as it receives on average from the sun.
0:06:24 > 0:06:28With this experiment, we're trying to create a simulation of
0:06:28 > 0:06:31what happens within one of Jupiter's bands.
0:06:31 > 0:06:33The water is heated but the edges
0:06:33 > 0:06:36in the centre of the vessel are cooled,
0:06:36 > 0:06:40this represents a warm band on Jupiter surrounded by
0:06:40 > 0:06:43colder air, and then the whole experimented is rotated.
0:06:44 > 0:06:48After a few minutes, some vortices are created that are
0:06:48 > 0:06:51so stable they barely appear to move.
0:06:52 > 0:06:56So what you can see in now is a whole chain of these eddies
0:06:56 > 0:06:59that are circulating in the same sense.
0:06:59 > 0:07:01So if this was a band on Jupiter,
0:07:01 > 0:07:04at the bottom of the band the winds are going this way round
0:07:04 > 0:07:07and then you've got these eddies spinning like this,
0:07:07 > 0:07:11- but at the top, the winds are going the other way.- That's right.
0:07:11 > 0:07:14So this is just like the bright bands on Jupiter.
0:07:14 > 0:07:16So in the south, the jets will be going in one direction,
0:07:16 > 0:07:19and to the north, they'll be going in the opposite direction
0:07:19 > 0:07:21with these vortices rolling in between them.
0:07:21 > 0:07:25These rotating storms are trapped within the bands that have been
0:07:25 > 0:07:28created by Jupiter's fast rotation.
0:07:29 > 0:07:32This means they are remarkably stable.
0:07:32 > 0:07:34On Earth, storms come and go, but on Jupiter
0:07:34 > 0:07:36the really memorable thing about Great Red Spot
0:07:36 > 0:07:38is it's been there for so long.
0:07:38 > 0:07:40These little storms you've generated
0:07:40 > 0:07:41in this experiment are just persisting.
0:07:41 > 0:07:43These features will persist
0:07:43 > 0:07:45for as long as we keep the experiment running,
0:07:45 > 0:07:47once the whole thing has settled down.
0:07:47 > 0:07:50This is just a two-dimensional representation
0:07:50 > 0:07:52of what might be happening on Jupiter,
0:07:52 > 0:07:55but our knowledge doesn't go much beyond that.
0:07:55 > 0:07:58The problem is that when we look at the planet,
0:07:58 > 0:08:00all we can see are the tops of the clouds
0:08:00 > 0:08:03and it's really difficult to measure what's underneath that.
0:08:04 > 0:08:07Finding out what's happening deep within the planet
0:08:07 > 0:08:09is the next great challenge.
0:08:12 > 0:08:15Luckily, there's hope that we all resolve some of these
0:08:15 > 0:08:17unanswered questions in the near future
0:08:17 > 0:08:21because NASA's Juno probe is on its way to Jupiter.
0:08:21 > 0:08:24It's spent the last couple of years wandering around the inner
0:08:24 > 0:08:27Solar System picking up speed, and at the end of last year, it
0:08:27 > 0:08:30passed by Earth for its final gravity assist.
0:08:30 > 0:08:34Remarkably, amateur astronomers were able to image it as it flew past.
0:08:34 > 0:08:37In this sequence of images from Peter Birtwhistle,
0:08:37 > 0:08:39the moving dot you can see is Juno itself
0:08:39 > 0:08:41heading off to Jupiter.
0:08:43 > 0:08:45Juno's on-board instrumentation will allow us
0:08:45 > 0:08:48to peer below the clouds for the first time.
0:08:48 > 0:08:50It will fly very close to the planet,
0:08:50 > 0:08:53a mere 5,000km above the clouds
0:08:53 > 0:08:54and below the radiation belt,
0:08:54 > 0:08:57which has stopped us from taking detailed data in the past.
0:08:57 > 0:08:59It will take detailed gravitational measurements
0:08:59 > 0:09:01and measure the atmospheric composition,
0:09:01 > 0:09:05it will also measure the mass of Jupiter's core, if there is one.
0:09:05 > 0:09:08It's an incredibly exciting mission but we'll have to wait
0:09:08 > 0:09:11until 2016 for Juno to arrive.
0:09:19 > 0:09:21Now you don't need to travel to Jupiter
0:09:21 > 0:09:23to get a fantastic image of it.
0:09:23 > 0:09:25It's possible to capture really
0:09:25 > 0:09:28detailed pictures of the planet from right here on Earth.
0:09:29 > 0:09:32And images like these, taken by amateurs,
0:09:32 > 0:09:36actually provide a unique record that even the space probes can't match.
0:09:38 > 0:09:40I've been speaking with Professor John Rogers,
0:09:40 > 0:09:42who gathers these images into a database
0:09:42 > 0:09:44that scientists can use.
0:09:44 > 0:09:46How are amateurs helping us understand Jupiter,
0:09:46 > 0:09:48where professionals can't?
0:09:48 > 0:09:50Well, amateurs are able to monitor Jupiter continuously,
0:09:50 > 0:09:53and its weather systems evolve over timescales from days,
0:09:53 > 0:09:56to months, to years, to decades,
0:09:56 > 0:09:58so we really need continuous observations
0:09:58 > 0:10:00to work out what's happening.
0:10:00 > 0:10:03They're not just doing observations, they're doing some science too?
0:10:03 > 0:10:06Yes, well, we can actually compile a record of what's going on,
0:10:06 > 0:10:09how spots like the Great Red Spot evolved,
0:10:09 > 0:10:12and we are able to monitor much smaller spots as well.
0:10:12 > 0:10:15Here for instance, you see the Great Red Spot, you can
0:10:15 > 0:10:18also see that the belts are not symmetrical.
0:10:18 > 0:10:21This dark belt is here but there's normally a dark belt up here,
0:10:21 > 0:10:24which, on this occasion in 2010, has disappeared.
0:10:24 > 0:10:27So these kind of changes are happening all the time on Jupiter,
0:10:27 > 0:10:29sometimes they take many years to unfold,
0:10:29 > 0:10:32and that's what amateurs can really study.
0:10:32 > 0:10:34I'm not used to seeing Jupiter in this orientation.
0:10:34 > 0:10:37This is the way that amateurs most commonly see it, with south up.
0:10:37 > 0:10:40So the Great Red Spot is in the southern atmosphere
0:10:40 > 0:10:42and that's how we put all our pictures up for display.
0:10:42 > 0:10:45But it's not just weather that the amateurs are spotting,
0:10:45 > 0:10:48they also find impacts.
0:10:48 > 0:10:51In 1994, the comet Shoemaker-Levy 9
0:10:51 > 0:10:53crashed into Jupiter,
0:10:53 > 0:10:56leaving dark scars in its atmosphere.
0:10:56 > 0:10:59Since then, amateurs have discovered that these
0:10:59 > 0:11:02kinds of impacts are more common than previously thought.
0:11:02 > 0:11:06In 2009, quite unexpectedly, an amateur, Anthony Wesley,
0:11:06 > 0:11:08discovered such a spot on the planet.
0:11:08 > 0:11:11This was an image he took two nights earlier,
0:11:11 > 0:11:13and then he saw this remarkably black spot
0:11:13 > 0:11:17appearing and realised that this might well be an impact.
0:11:17 > 0:11:20So other amateurs immediately started taking images to confirm
0:11:20 > 0:11:23and professional scientists took this image
0:11:23 > 0:11:25in a far-infrared wavelength.
0:11:25 > 0:11:28The Hubble Space Telescope took this image a few days lays later.
0:11:28 > 0:11:30The professional astronomers managed to follow this event
0:11:30 > 0:11:32over several months,
0:11:32 > 0:11:35while the amateurs were also tracking over several months.
0:11:35 > 0:11:37The amateurs are the watchkeepers, they keep on eye on Jupiter
0:11:37 > 0:11:40and alert the professionals when something exciting happens?
0:11:40 > 0:11:42Yes, indeed.
0:11:42 > 0:11:46More recently, amateurs have been noticing impacts while they happen.
0:11:46 > 0:11:49They are much smaller impacts, they don't leave visible scars
0:11:49 > 0:11:54but they're more frequent. And so three times since 2009,
0:11:54 > 0:11:56amateurs have actually seen fireballs in the atmosphere
0:11:56 > 0:11:59of Jupiter, which previously, if anyone had seen them,
0:11:59 > 0:12:02they didn't notice them or didn't believe they were seeing them.
0:12:02 > 0:12:05But now we have real webcam videos and it's clear that
0:12:05 > 0:12:09amateurs are actually detecting flashes as they occur.
0:12:09 > 0:12:12So how does an amateur get involved?
0:12:12 > 0:12:15The best way for someone who hasn't done it before is to
0:12:15 > 0:12:17contact their local astronomical society.
0:12:17 > 0:12:19There they'll meet people who are themselves
0:12:19 > 0:12:21getting into the same kind of observations,
0:12:21 > 0:12:24finding out how to use the same kind of equipment,
0:12:24 > 0:12:26and I think that it's the personal contacts
0:12:26 > 0:12:27that are most useful to someone
0:12:27 > 0:12:30who hasn't experienced this kind of technology before.
0:12:30 > 0:12:32Thanks, John, that was pretty fascinating
0:12:32 > 0:12:36- and it shows the power of amateur astronomy.- Thank you.
0:12:43 > 0:12:46Now Pete Lawrence is here with his guide to what else you can
0:12:46 > 0:12:49see in the night sky around Jupiter.
0:12:49 > 0:12:52But first, he's got a simple tip that can help address
0:12:52 > 0:12:56one of the main problems that people face when they're stargazing -
0:12:56 > 0:12:59how to match a star chart to the real night sky.
0:12:59 > 0:13:04And he's with the Hampshire Astronomical Group on the South Downs.
0:13:04 > 0:13:06Jupiter is pretty easy to find at the moment
0:13:06 > 0:13:09because it's the brightest thing visible in the early evening
0:13:09 > 0:13:13part of the night sky, apart from when the moon's about, of course.
0:13:13 > 0:13:15For many people, when they look up at the night sky,
0:13:15 > 0:13:19it can be a bit of a challenge to work out what is what.
0:13:19 > 0:13:22But there are a few simple tips you can follow which will
0:13:22 > 0:13:23make your life easier.
0:13:23 > 0:13:27One of most difficult things for those starting out
0:13:27 > 0:13:28is judging scale.
0:13:28 > 0:13:32How do you relate the distance between stars on a star chart
0:13:32 > 0:13:35to the distance in the night sky?
0:13:35 > 0:13:36It might sound surprising,
0:13:36 > 0:13:39but the best thing to do is to use your hands.
0:13:41 > 0:13:43If you hold it out at arm's length,
0:13:43 > 0:13:46like that, the distance between your thumb
0:13:46 > 0:13:48and little finger is the same.
0:13:48 > 0:13:50If you've got big hands or little hands,
0:13:50 > 0:13:53the length of your arm tends to compensate for it.
0:13:53 > 0:13:54So if you look at Orion - you can
0:13:54 > 0:13:56see the bright star in the upper left corner
0:13:56 > 0:13:59and the bright star in the lower right corner - you can
0:13:59 > 0:14:02see that it fits more or less between those two.
0:14:02 > 0:14:04For all of us, even though
0:14:04 > 0:14:07we've got different sized hands and different length of arms,
0:14:07 > 0:14:11you can actually hold two fingers up as well, that's a good indicator.
0:14:11 > 0:14:14Just starting to appreciate the scale of patterns in the night sky
0:14:14 > 0:14:17and you can relate that back to a star chart
0:14:17 > 0:14:20and then gradually work your way across the sky.
0:14:20 > 0:14:24Once you understand the apparent distances between stars,
0:14:24 > 0:14:27finding anything in the sky should be much easier.
0:14:28 > 0:14:31Jupiter is obviously the highlight up there at the moment,
0:14:31 > 0:14:32it's magnificent.
0:14:32 > 0:14:36But there's a lot more to be seen around that area and I've picked out
0:14:36 > 0:14:40some of my favourite highlights for this month's star guide.
0:14:42 > 0:14:45The magnificent constellation of Orion lies south in the early
0:14:45 > 0:14:47evening during February.
0:14:47 > 0:14:50Its seven bright stars are easy to pick out
0:14:50 > 0:14:53and create a great signpost in the night sky.
0:14:53 > 0:14:57Look out in particular for Orion's Sword that appears to hang
0:14:57 > 0:15:01down from the belt, a region which contains the fabulous Orion Nebula.
0:15:03 > 0:15:04Follow the line made by
0:15:04 > 0:15:06Orion's Belt down the left
0:15:06 > 0:15:07to locate Sirius -
0:15:07 > 0:15:10the brightest night-time star.
0:15:10 > 0:15:11About one-and-a-half
0:15:11 > 0:15:13outstretched hand widths
0:15:13 > 0:15:15above and left of Sirius is another
0:15:15 > 0:15:18bright star called Procyon.
0:15:21 > 0:15:23Join the dots of Sirius, Procyon
0:15:23 > 0:15:25and orange Betelgeuse to form
0:15:25 > 0:15:26a pattern known as
0:15:26 > 0:15:27the Winter Triangle.
0:15:27 > 0:15:29The winter Milky Way
0:15:29 > 0:15:31passes through this region.
0:15:31 > 0:15:32Scanning the area
0:15:32 > 0:15:33with a pair of binoculars
0:15:33 > 0:15:34reveals many faint
0:15:34 > 0:15:36and beautiful star clusters.
0:15:41 > 0:15:44Extend a line from Rigel, in Orion,
0:15:44 > 0:15:47through Betelgeuse for twice the distance again -
0:15:47 > 0:15:50that's two outstretched hand widths -
0:15:50 > 0:15:51to arrive at a pair of stars
0:15:51 > 0:15:55in Gemini known as Castor and Pollux.
0:15:55 > 0:15:58They are about three finger widths apart.
0:16:01 > 0:16:05If you traced the pattern of the famous twins back towards Orion,
0:16:05 > 0:16:10you'll find the unmistakably bright planet Jupiter.
0:16:12 > 0:16:15Jupiter is currently visible more or less all night long.
0:16:15 > 0:16:19If you go out and catch it early, it's possible to see
0:16:19 > 0:16:22a full rotation of the planet, that's one whole day on Jupiter.
0:16:22 > 0:16:25If you get some lovely pictures of that, send them in to us
0:16:25 > 0:16:27and we'll put the best ones up on our website.
0:16:28 > 0:16:30Speaking of your photos, we've got
0:16:30 > 0:16:33some great ones that have been uploaded to our website.
0:16:33 > 0:16:36And here are a few that really stand out.
0:16:39 > 0:16:43This is the Orion Nebula, which lies on Orion's Sword,
0:16:43 > 0:16:44taken by Steve Richards.
0:16:47 > 0:16:49Luke Stacy captured this image
0:16:49 > 0:16:52of a chain of sun spots on 2nd February.
0:16:58 > 0:17:01This shot by Mary Spicer shows how light bouncing off
0:17:01 > 0:17:05the Earth can illuminate the parts of the moon that lie in shadow.
0:17:06 > 0:17:08And this is Centaurus A,
0:17:08 > 0:17:12a galaxy that lies too far south to be viewed directly from Britain.
0:17:12 > 0:17:17It was taken over an astonishing 43 nights by Rolf Olson.
0:17:17 > 0:17:20To send us your images, go to our website at...
0:17:23 > 0:17:25Since we were last on air,
0:17:25 > 0:17:27there has been plenty happening in the astronomical world
0:17:27 > 0:17:31- and the most spectacular event has been a new supernova.- Yes.
0:17:31 > 0:17:35A supernova is the dying throes of larger stars.
0:17:35 > 0:17:38And we have one here captured by some UCL students.
0:17:38 > 0:17:41So this is the M82 cigar galaxy.
0:17:41 > 0:17:45And here, on 21st January, we have a new bright object - the supernova.
0:17:45 > 0:17:48And what I love about this is this discovery was made by Steve Fossey
0:17:48 > 0:17:50and a bunch of students just up the road
0:17:50 > 0:17:53at the UCL's Mill Hill observatory.
0:17:53 > 0:17:56But even better, it was a ten-minute gap where it wasn't cloudy.
0:17:56 > 0:18:00- Exactly. A discovery from within the M25.- And it's perfect.
0:18:00 > 0:18:04- It's a type 1a supernova, which are quite rare.- That's right.
0:18:04 > 0:18:07We use these to measure how the universe is expanding.
0:18:07 > 0:18:10So they're bright, so you can see them from a long distance away,
0:18:10 > 0:18:11and that means we can use them
0:18:11 > 0:18:14to work out how the universe is accelerating.
0:18:14 > 0:18:16But, embarrassingly, we don't know what they are.
0:18:16 > 0:18:19We've ideas that they might be a massive star spiralling
0:18:19 > 0:18:23material down onto a white dwarf, which then explodes, but we're
0:18:23 > 0:18:25not sure and that's why we need these local ones to try and help us.
0:18:25 > 0:18:27This is 12 million light years away
0:18:27 > 0:18:29- which is pretty local. - Just round the corner.
0:18:29 > 0:18:32Yes! Is still visible now or does it decay very rapidly?
0:18:32 > 0:18:34It will be visible for the next few months.
0:18:34 > 0:18:38It was caught early enough that it was still brightening
0:18:38 > 0:18:40so it will be at its brightest about now.
0:18:40 > 0:18:41So go out, find M82.
0:18:41 > 0:18:44If you look in binoculars, you should see it easily.
0:18:44 > 0:18:46It won't quite make it to naked eye visibility
0:18:46 > 0:18:48unless something odd happens
0:18:48 > 0:18:50but it'll be an easy target for binoculars.
0:18:50 > 0:18:51The brightest supernova
0:18:51 > 0:18:53we've had in the northern hemisphere for years.
0:18:53 > 0:18:56Speaking of celestial spectaculars, we had hoped before
0:18:56 > 0:19:00Christmas that comet ISON was going to put on a great show for us
0:19:00 > 0:19:02but it didn't quite work out like that
0:19:02 > 0:19:05and Alan Fitzsimmons is going to tell us why.
0:19:06 > 0:19:11People were predicting that ISON would be the comet of the century
0:19:11 > 0:19:13that, as it came round the sun,
0:19:13 > 0:19:16a huge tail would be created that would fill the night sky.
0:19:17 > 0:19:21However, instead, it seems to have fizzled out.
0:19:21 > 0:19:26But now, by pulling data from a number of scientific instruments,
0:19:26 > 0:19:29it's possible to find out what actually happened.
0:19:29 > 0:19:31Here we've got the comet
0:19:31 > 0:19:34about a couple of hours before closest approach to the sun.
0:19:34 > 0:19:37We can already see that something has happened to the comet.
0:19:37 > 0:19:39In a normal comet, we expect to see
0:19:39 > 0:19:42a very bright, distinct head, or coma,
0:19:42 > 0:19:43form from all the gas
0:19:43 > 0:19:47and small dust particles that the comet has released.
0:19:47 > 0:19:50Here we can see the tail of the comet
0:19:50 > 0:19:52but the head itself is already
0:19:52 > 0:19:56not looking like a normal comet does -
0:19:56 > 0:19:57it's spread out.
0:19:57 > 0:19:59And even by this point,
0:19:59 > 0:20:01a couple of hours before it reached
0:20:01 > 0:20:02its closest point to the sun,
0:20:02 > 0:20:04the comet nucleus itself
0:20:04 > 0:20:06had been dispersed. Interestingly,
0:20:06 > 0:20:09it's still far enough from the sun that it shouldn't have been
0:20:09 > 0:20:11broken up by the gravitational field,
0:20:11 > 0:20:14the tidal forces imparted on the nucleus by the sun,
0:20:14 > 0:20:18but what's happened is simply its nucleus has been heated
0:20:18 > 0:20:22so much and is releasing so much gas and material from its surface,
0:20:22 > 0:20:26that pressure of that material building up in the comet
0:20:26 > 0:20:28has simply broken it apart.
0:20:30 > 0:20:33And so ISON was doomed long before it reached the sun.
0:20:33 > 0:20:35And as it passed around our star,
0:20:35 > 0:20:39it reappeared as nothing more than a cloud of debris.
0:20:40 > 0:20:42But there is still a question about
0:20:42 > 0:20:46whether anything of the nucleus had survived to live another day.
0:20:47 > 0:20:52On December 16th, the Hubble Space Telescope went to have
0:20:52 > 0:20:54a look at where the comet was predicted to be.
0:20:54 > 0:20:59Now it's tracking where we expect the comet to be moving,
0:20:59 > 0:21:03so all the background stars and galaxies appear as streaks.
0:21:03 > 0:21:06But if there was any comet left, we would see it as a point-like
0:21:06 > 0:21:08source here and we don't see anything.
0:21:08 > 0:21:11So these Hubble Telescope images here
0:21:11 > 0:21:16imply that there really isn't anything left at all of the nucleus.
0:21:16 > 0:21:19So it's a shame. ISON is gone -
0:21:19 > 0:21:22but it gave us a great show on its way in.
0:21:25 > 0:21:29And we've got one more item of news this month.
0:21:29 > 0:21:31In January, as part of Stargazing LIVE,
0:21:31 > 0:21:35I challenged people to go online and look at pictures of galaxies
0:21:35 > 0:21:37and look for gravitational lenses -
0:21:37 > 0:21:40places where a distant galaxy has had its light bent
0:21:40 > 0:21:43by a gravitational lens, by passing near a nearby galaxy.
0:21:43 > 0:21:46We found lots of spectacular things
0:21:46 > 0:21:48but the one we talked about on the night was this one.
0:21:48 > 0:21:52- This is an infrared image of that galaxy.- Yes. What have we got?
0:21:52 > 0:21:55- In the centre, that's the galaxy? - That's the nearby galaxy.
0:21:55 > 0:21:57And the red arc that you can see, almost the red ring there,
0:21:57 > 0:22:00is a distant galaxy whose light has been bent
0:22:00 > 0:22:03and we're seeing it because it's being lensed by this nearby galaxy.
0:22:03 > 0:22:06Without that galaxy, we wouldn't have a chance of seeing it?
0:22:06 > 0:22:07Exactly. It's nature's telescope.
0:22:07 > 0:22:10This is the infrared. What we've been doing since
0:22:10 > 0:22:12is we've looked at it in the radio using Jodrell.
0:22:12 > 0:22:15- This is the image that we've got. - It does look like different.
0:22:15 > 0:22:16It does.
0:22:16 > 0:22:19For starters, it's blobby because it's a radio image
0:22:19 > 0:22:22and you don't get the beautiful pictures you do in the infrared.
0:22:22 > 0:22:25The other thing, I don't know if I can convince you of this,
0:22:25 > 0:22:27but in the infrared we saw that red ring,
0:22:27 > 0:22:28in the radio, it's only one arc.
0:22:28 > 0:22:31It definitely looks one-sided.
0:22:31 > 0:22:34- So where's the rest of it gone? - Exactly. It's quite confusing.
0:22:34 > 0:22:37Our best guess at the minute is that the radio
0:22:37 > 0:22:40and the infrared radiation come from different parts of the galaxy.
0:22:40 > 0:22:42So the infrared comes from star formation spread out through
0:22:42 > 0:22:45the whole galaxy - and the galaxy's forming stars at a great rate,
0:22:45 > 0:22:47about 100 times that of the Milky Way.
0:22:47 > 0:22:50And the radio, we think, comes from right in the centre,
0:22:50 > 0:22:53from the nucleus where material is spiralling onto
0:22:53 > 0:22:56what must be a growing black hole in the centre of this galaxy.
0:22:56 > 0:22:58This is what I love. Looking at the sky
0:22:58 > 0:23:00in different bands of the electromagnetic spectrum
0:23:00 > 0:23:03gives you a very different viewpoint and different understandings.
0:23:03 > 0:23:05That's right. We knew that was true.
0:23:05 > 0:23:07It's only the second time that we've seen this
0:23:07 > 0:23:10misalignment between a radio lens and an infrared lens.
0:23:10 > 0:23:13A perfect ring in the infrared and nice to blobby arc in the radio.
0:23:13 > 0:23:15It's quite fun.
0:23:15 > 0:23:16If you go to the Sky At Night website,
0:23:16 > 0:23:19we've actually put some more data online. If you follow the link,
0:23:19 > 0:23:22you might be able to discover your own lensed galaxy.
0:23:28 > 0:23:30Well, back to Jupiter, and we're in the Endeavour Room
0:23:30 > 0:23:32of the Royal Observatory Greenwich,
0:23:32 > 0:23:35which these days is a library but which used to house
0:23:35 > 0:23:37some of the largest telescopes on the site.
0:23:37 > 0:23:40It was in this room, in 1908, that British astronomer
0:23:40 > 0:23:43Melotte discovered a moon of Jupiter.
0:23:43 > 0:23:48This is the image and this dot here is the moon we now call Pasiphae.
0:23:48 > 0:23:51Exciting things are happening with the moons of Jupiter
0:23:51 > 0:23:53and to discuss them I'm joined by Dr Leigh Fletcher,
0:23:53 > 0:23:55an expert on the Jupiter system.
0:23:55 > 0:23:57- Leigh, welcome to the programme. - Thank you.
0:23:57 > 0:23:59We're going to talk about Europa,
0:23:59 > 0:24:02where jets of water have been discovered shooting into space.
0:24:02 > 0:24:04We knew there was water on Europa already.
0:24:04 > 0:24:07We did. Europa has always been a tantalising place for us
0:24:07 > 0:24:11to one day go and explore and now more so with this new result of
0:24:11 > 0:24:15plumes of water vapour being emitted from the south pole of Europa.
0:24:15 > 0:24:18It's going to be a fabulous thing for us to go and look at one day.
0:24:18 > 0:24:21Europa's an icy moon and that's what we see when we look at the surface.
0:24:21 > 0:24:25Europa is the second of four Galilean satellites in orbit
0:24:25 > 0:24:28around the Jupiter. It's about the size of our own moon.
0:24:28 > 0:24:30If you look at it here on the screen, you can see.
0:24:30 > 0:24:32It's an icy ball, Europa is,
0:24:32 > 0:24:35and the different colours that you see across the surface
0:24:35 > 0:24:38are contaminants in the ice itself.
0:24:38 > 0:24:41It almost looks like you've got a frozen ice raft,
0:24:41 > 0:24:45frozen then into a body of liquid water that has re-frozen.
0:24:45 > 0:24:47We call it chaos terrain.
0:24:47 > 0:24:50- We can zoom in to get a proper look.- Yeah.- There we go.
0:24:50 > 0:24:53This is one of the key pieces of evidence which suggests
0:24:53 > 0:24:56that beneath this terrain there is liquid water.
0:24:56 > 0:25:01Liquid water in our solar system locked away beneath the icy service.
0:25:01 > 0:25:04We've been talking about this for years. There's an annoying catch,
0:25:04 > 0:25:06isn't there, that the ice is pretty thick?
0:25:06 > 0:25:10This is the typical thing within our solar system of the ability
0:25:10 > 0:25:13to sense what we really want to see, which is that ocean,
0:25:13 > 0:25:16is forbidden to us because it's hidden away,
0:25:16 > 0:25:17locked away, or so we thought.
0:25:17 > 0:25:21But now, with the discovery of these water vapour plumes,
0:25:21 > 0:25:24we have a tantalising chance to fly through those plumes
0:25:24 > 0:25:27- and sniff out the composition.- Let's look at that that new observation.
0:25:27 > 0:25:29This was released at the end of last year.
0:25:29 > 0:25:31It's a Hubble Space Telescope observation.
0:25:31 > 0:25:33And I have to say, Leigh, looking at this,
0:25:33 > 0:25:35it's not hugely convincing.
0:25:35 > 0:25:38I'm very sorry that you're disappointed but this is actually
0:25:38 > 0:25:40a really exciting discovery that the folks with
0:25:40 > 0:25:43the Hubble Space Telescope made just that while ago.
0:25:43 > 0:25:46Don't forget that you're seeing this from planet Earth,
0:25:46 > 0:25:48five astronomical units away.
0:25:48 > 0:25:50Five times as far away from the sun as the Earth is.
0:25:50 > 0:25:53Absolutely. All the way out at the orbit of Jupiter.
0:25:53 > 0:25:57This is an artist's impression superimposing the two together.
0:25:57 > 0:25:58What they're looking at here is
0:25:58 > 0:26:01ultraviolet emission from hydrogen and oxygen.
0:26:01 > 0:26:03So this is water that has been spewed out of the moon
0:26:03 > 0:26:08- and has then been disassociated, split apart...- By the sun's light.
0:26:08 > 0:26:09Exactly, by UV radiation.
0:26:09 > 0:26:12We can see that emanating from the south pole.
0:26:12 > 0:26:16We're talking about a plume of water 200km high
0:26:16 > 0:26:18over the south pole of Europa.
0:26:18 > 0:26:20I can tell you we didn't expect to see that.
0:26:20 > 0:26:22How have we got water at the south pole?
0:26:22 > 0:26:25What's going on here is we've got these cracks, and these fissures
0:26:25 > 0:26:29and stripes, which are undergoing different amounts of stress
0:26:29 > 0:26:31as the moon goes round Jupiter.
0:26:31 > 0:26:35The orbit of Europa around Jupiter is not perfectly circular
0:26:35 > 0:26:37and that means sometimes it's closer to Jupiter,
0:26:37 > 0:26:38where the gravity's stronger,
0:26:38 > 0:26:41and sometimes it's further away, where the gravity is weaker.
0:26:41 > 0:26:44Jupiter's a big thing, its pull is pretty significant.
0:26:44 > 0:26:46It's an immense gravitational field,
0:26:46 > 0:26:49that means, when Europa is far away from the moon...
0:26:49 > 0:26:50Like this observation.
0:26:50 > 0:26:54Like this observation in December 2012, things are relaxed,
0:26:54 > 0:26:57you're able to emanate these plumes out of the south pole.
0:26:57 > 0:27:00Now the team also have observations from just a month earlier.
0:27:00 > 0:27:03At that point, Europa was much closer in to Jupiter,
0:27:03 > 0:27:06so where the gravity field is stronger,
0:27:06 > 0:27:08if you like, no plumes were observed at that point.
0:27:08 > 0:27:11So you have this situation, extremely dynamically rich,
0:27:11 > 0:27:15where the plumes are only emanating their material into space
0:27:15 > 0:27:17when the stress is at its lowest point -
0:27:17 > 0:27:20at the furthest distance away from Jupiter.
0:27:20 > 0:27:23Now this is a fabulously exciting discovery.
0:27:23 > 0:27:24It provides access to this water -
0:27:24 > 0:27:27the stuff we thought was locked up under the surface -
0:27:27 > 0:27:29and you have a mission, or you're part of a team
0:27:29 > 0:27:32working on a mission, called JUICE, which is heading to Europa.
0:27:32 > 0:27:34How does this change your plans?
0:27:34 > 0:27:38It's being built by the European Space Agency to launch in 2022,
0:27:38 > 0:27:40or thereabouts and, at the moment,
0:27:40 > 0:27:44we are scheduled to have two flybys of Europa in 2031.
0:27:44 > 0:27:47We are going to be up close and personal with those plumes, able to
0:27:47 > 0:27:50look at the light as it is being filtered and scattered through them.
0:27:50 > 0:27:53We've even got instruments on-board capable of detecting
0:27:53 > 0:27:55the sorts of materials that are emanating.
0:27:55 > 0:27:58There's a huge caveat to that, I should say.
0:27:58 > 0:28:00What if this material isn't coming from the ocean?
0:28:00 > 0:28:03Maybe it's the action of something heating up
0:28:03 > 0:28:05in just the very top layers.
0:28:05 > 0:28:07Even then, it's still exciting because it's a way
0:28:07 > 0:28:08we can sample the surface materials
0:28:08 > 0:28:11from our spacecraft without landing on the surface.
0:28:11 > 0:28:13So when does JUICE get there?
0:28:13 > 0:28:17JUICE will get there in 2030 and it will fly by Europa twice in 2031.
0:28:17 > 0:28:20- Fabulous. Come back and tell us about it and good luck.- Thank you.
0:28:20 > 0:28:22- Leigh, thanks a lot.- Thank you.
0:28:28 > 0:28:31So that's it for this month, but do remember to keep on sending
0:28:31 > 0:28:34your pictures in, especially if you manage to get
0:28:34 > 0:28:37a full rotation of Jupiter, and we'll put the best on our website.
0:28:37 > 0:28:39When we come back next month, will be listening to the cosmos -
0:28:39 > 0:28:42studying sound waves to find out what they can tell us
0:28:42 > 0:28:45about the Universe's hidden secrets.
0:28:45 > 0:28:46And we'll also be looking at how to get
0:28:46 > 0:28:49wonderful images of the night sky with just a smartphone.
0:28:49 > 0:28:53- So remember, get outside and get looking up.- Good night.
0:28:53 > 0:28:58THEME MUSIC: "At The Castle Gate" from "Pelleas and Melisande Suite" by Jean Sibelius