0:00:37 > 0:00:41This month, we are at the Harwell Space Cluster, near Oxford,
0:00:41 > 0:00:46home to some of the biggest names in the exploration of our universe.
0:00:46 > 0:00:48There is the European Space Agency,
0:00:48 > 0:00:51the Rutherford Appleton Laboratory,
0:00:51 > 0:00:53and Chris and I have been invited
0:00:53 > 0:00:55to the new Satellite Applications Catapult,
0:00:55 > 0:00:59who are building business links to astronomy and space science.
0:01:00 > 0:01:03Tonight's programme is all about Saturn, one of the first things
0:01:03 > 0:01:06I saw through a telescope and still my favourite planet.
0:01:06 > 0:01:11Saturn is famous for its fantastic rings, but there is so much more
0:01:11 > 0:01:15to this mysterious planet, including its very strange moons.
0:01:15 > 0:01:16Chris North is here too,
0:01:16 > 0:01:19and he'll be answering some of your Space Surgery questions.
0:01:19 > 0:01:22And because Saturn is so well placed in the night sky at the minute,
0:01:22 > 0:01:25Peter and Paul have headed off to Hampshire
0:01:25 > 0:01:27to see if they can catch a glimpse.
0:01:27 > 0:01:29Oh, my word! Look at that.
0:01:29 > 0:01:31I think that's the best view I've had of Saturn all night.
0:01:31 > 0:01:35Yeah, I think you're absolutely right.
0:01:35 > 0:01:36Spectacular Saturn,
0:01:36 > 0:01:39out amongst the stars of Virgo.
0:01:42 > 0:01:46The reason we have such amazing images of Saturn and its moons
0:01:46 > 0:01:51is because we've had a spacecraft there for almost ten years - Cassini.
0:01:53 > 0:01:56Cassini has an amazing camera
0:01:56 > 0:02:00and we have been astounded by the images it has been sending back,
0:02:00 > 0:02:03forcing us to rethink our ideas about Saturn,
0:02:03 > 0:02:06its rings and its moons.
0:02:08 > 0:02:10It can see in different wavelengths -
0:02:10 > 0:02:15useful if you want to peer through the layers of Saturn's atmosphere.
0:02:16 > 0:02:20We're joined by Leigh Fletcher to tell us about stunning Saturn.
0:02:20 > 0:02:23Now, Leigh, Saturn is basically a giant ball of gas, isn't it?
0:02:23 > 0:02:26That's right. It's an enormous ball of gas
0:02:26 > 0:02:29that's 95 times more heavy than Planet Earth.
0:02:29 > 0:02:31But, in fact, because its density is so low,
0:02:31 > 0:02:34it's made mostly of hydrogen and helium, if you were able
0:02:34 > 0:02:37to take it and put it in a bathtub, it would float on water.
0:02:37 > 0:02:40- It's the least dense planet in the solar system.- That's right.
0:02:40 > 0:02:44Here we're seeing it fantastically lit up by the sun on this side
0:02:44 > 0:02:45and rings casting beautiful shadows.
0:02:45 > 0:02:47Yeah, you're seeing the shadow of the rings
0:02:47 > 0:02:50and one of the important things about this image is, it shows you
0:02:50 > 0:02:52that Saturn normally looks rather bland
0:02:52 > 0:02:55compared to something like Jupiter, that you're familiar with.
0:02:55 > 0:02:58But even though it looks featureless, there are indications
0:02:58 > 0:03:02- of very dynamic things happening in Saturn's atmosphere.- Oh, absolutely.
0:03:02 > 0:03:04It's a meteorologist's paradise.
0:03:04 > 0:03:06We can actually study the weather system of this giant planet
0:03:06 > 0:03:09and one of the beauties of having Cassini there
0:03:09 > 0:03:11for almost a decade now is that we can explore
0:03:11 > 0:03:14all the different seasons taking place in this giant.
0:03:14 > 0:03:17So if we go to the next image, we can see a storm on Saturn.
0:03:17 > 0:03:20We do get storm activity occurring.
0:03:20 > 0:03:22It's maybe not quite as dramatic as something like Jupiter.
0:03:22 > 0:03:25Yeah, it doesn't stand out quite as much as Jupiter's great red spot.
0:03:25 > 0:03:29It does look slightly like the world's largest seagull!
0:03:29 > 0:03:30But every now and then,
0:03:30 > 0:03:33you get something really special happening on Saturn
0:03:33 > 0:03:36and we were lucky enough with Cassini to witness such an event
0:03:36 > 0:03:38over the last couple of years.
0:03:38 > 0:03:39Well, let's go back to look at that.
0:03:39 > 0:03:44- Let's start with December 2010, so that's this image here.- There we go.
0:03:44 > 0:03:45There's something going on,
0:03:45 > 0:03:47there's a little storm, but not much going on,
0:03:47 > 0:03:49and then where shall we go next? January, I guess.
0:03:49 > 0:03:52- Oh, and it's broken out here. - You can see the difference
0:03:52 > 0:03:54between these two images
0:03:54 > 0:03:56over just a month of time.
0:03:56 > 0:03:57So the storm has popped up
0:03:57 > 0:03:59and it's popped up into these winds
0:03:59 > 0:04:01that are rapidly circulating around Saturn
0:04:01 > 0:04:03and it's starting to be drawn up.
0:04:03 > 0:04:05Let's go on to February 2011,
0:04:05 > 0:04:07and you can really see what that's done to the storm,
0:04:07 > 0:04:09so this storm has been stretched out.
0:04:09 > 0:04:11We should say, these winds you described on Saturn,
0:04:11 > 0:04:14- they're some of the solar system's fastest.- That's right,
0:04:14 > 0:04:17and this goes back to the idea that it's Saturn's own internal energy
0:04:17 > 0:04:20which is powering and creating these very fast winds.
0:04:20 > 0:04:23The thing that strikes me is the detail available in this image,
0:04:23 > 0:04:26so let's bring the storm up and put it right across the screen
0:04:26 > 0:04:27and you'll see what I mean.
0:04:27 > 0:04:29We've got incredible details here,
0:04:29 > 0:04:30and this is the head of the storm
0:04:30 > 0:04:33and if you think that the Earth is the size of this image,
0:04:33 > 0:04:36you get a sense of how big this thing really is.
0:04:36 > 0:04:38What's happening in this swirling cloud structure?
0:04:38 > 0:04:41Well, we had this huge plume of activity
0:04:41 > 0:04:43dredging up ammonia ice and water ice,
0:04:43 > 0:04:45and it deposited it at the cloud tops,
0:04:45 > 0:04:48and so the winds that are taking place in the clouds
0:04:48 > 0:04:50then waft all of this material downstream.
0:04:50 > 0:04:52At the same time, we were detecting
0:04:52 > 0:04:55super Saturnian lightning bolts within this atmosphere,
0:04:55 > 0:04:57which create this incredible structure.
0:04:57 > 0:05:00What is it we have happening here? Is this the head of the storm now?
0:05:00 > 0:05:03This I like to think of as the heart of the storm itself.
0:05:03 > 0:05:05What you're seeing here
0:05:05 > 0:05:09is the birth of a large churning vortex within Saturn's cloud tops.
0:05:09 > 0:05:11So these storms are absolutely fascinating,
0:05:11 > 0:05:14but actually, there's some really interesting activity
0:05:14 > 0:05:17happening up at the poles of Saturn, so let's have a look at those.
0:05:17 > 0:05:19Right. So what do we have here?
0:05:19 > 0:05:22You immediately see so much more detail.
0:05:22 > 0:05:25The thing that really stands out in this image for me
0:05:25 > 0:05:29is the large-scale structure, this incredible hexagonal wave.
0:05:29 > 0:05:33We don't see anything like this anywhere else in the solar system.
0:05:33 > 0:05:36We don't know why it's a hexagon,
0:05:36 > 0:05:39and this goes back to what we were talking about with a plughole,
0:05:39 > 0:05:41a swirling vortex of air
0:05:41 > 0:05:44right at the north pole of Saturn.
0:05:44 > 0:05:47- So what comes up at the equator goes down in the poles.- Must come down.
0:05:47 > 0:05:49Cassini captured this particular movie...
0:05:49 > 0:05:53- Oh, wow.- That's fantastic. - ..back in November of last year.
0:05:53 > 0:05:56You can see this incredible, churning weather system.
0:05:56 > 0:05:58That plughole you keep referring to
0:05:58 > 0:06:01is right in the heart of this swirling vortex.
0:06:01 > 0:06:05Now, the gas that's contained within this vortex is hot,
0:06:05 > 0:06:09and you know that if you squeeze a gas together, it heats up,
0:06:09 > 0:06:12and that sinking action is heating the air
0:06:12 > 0:06:14within this swirling hurricane.
0:06:14 > 0:06:17They're fabulous images and fantastic science,
0:06:17 > 0:06:19so, Leigh, thank you very much.
0:06:19 > 0:06:23And fantastic though Saturn is, it's now time to look at the rings.
0:06:31 > 0:06:35The rings of Saturn never fail to look spectacular.
0:06:35 > 0:06:37We can see them quite clearly,
0:06:37 > 0:06:39even through a small telescope
0:06:39 > 0:06:43but get up close and you see they are extremely complex,
0:06:43 > 0:06:46made of hundreds of individual ringlets,
0:06:46 > 0:06:50with some extending far out into space.
0:06:51 > 0:06:56What's mind-blowing is that these structures are not solid.
0:06:56 > 0:07:01They're made largely of tiny pieces of ice, dust and small rocks.
0:07:03 > 0:07:07There are small moons running round within the rings,
0:07:07 > 0:07:08called shepherd moons,
0:07:08 > 0:07:13which create gaps and form these amazing structures.
0:07:13 > 0:07:17But Saturn's rings still hold many mysteries.
0:07:17 > 0:07:19Crucially, we still don't know
0:07:19 > 0:07:21how or when the rings were formed,
0:07:21 > 0:07:24but there are a couple of opposing theories.
0:07:28 > 0:07:30This is a fantastic image of Saturn
0:07:30 > 0:07:33showing its rings beautifully on our video wall.
0:07:33 > 0:07:36Now, Saturn's being backlit, the sun is setting behind.
0:07:36 > 0:07:38You can just see the sunlight coming through here,
0:07:38 > 0:07:40and this is us here on the Earth,
0:07:40 > 0:07:43but they look absolutely fantastic, Chris, these rings.
0:07:43 > 0:07:46It's amazing to see the Earth through Saturn's rings,
0:07:46 > 0:07:48but the rings themselves are exciting too
0:07:48 > 0:07:49and new results from Cassini
0:07:49 > 0:07:52have told us they're even more interesting than we thought.
0:07:52 > 0:07:53One thing that surprised me
0:07:53 > 0:07:56was that the rings are thinner than we thought.
0:07:56 > 0:07:58They're just, in places, 10 to 30 metres thick,
0:07:58 > 0:08:01so that's about the height of a three-storey building
0:08:01 > 0:08:05and something that thin produces this spectacular structure.
0:08:05 > 0:08:08One of the other mysteries about the rings is how old they are.
0:08:08 > 0:08:10People have argued that because they're very bright,
0:08:10 > 0:08:12they must be made of fresh water ice
0:08:12 > 0:08:14or they have fresh water ice within them,
0:08:14 > 0:08:16and if there's fresh ice,
0:08:16 > 0:08:20that means they're young rings, no more than a few million years old.
0:08:20 > 0:08:22But you could also argue that the rings are in fact very old
0:08:22 > 0:08:24and they're something that formed
0:08:24 > 0:08:27close in time to the formation of the planet itself.
0:08:27 > 0:08:30It's one of the key things that we need to understand about Saturn.
0:08:30 > 0:08:33Whether the rings are old or young, they're certainly beautiful,
0:08:33 > 0:08:34but we can't talk about Saturn
0:08:34 > 0:08:37without also mentioning its family of amazing moons.
0:08:42 > 0:08:46The moons of Saturn are strange, wonderful and plentiful,
0:08:46 > 0:08:49with the current tally running to 62,
0:08:49 > 0:08:52most of them discovered within the last 15 years.
0:08:54 > 0:08:56There's Mimas, the "Death Star moon"
0:08:56 > 0:08:59with its large impact crater.
0:08:59 > 0:09:01Then there's Iapatus, the "yin-yang moon"
0:09:01 > 0:09:04and thanks to Cassini, we now know that its odd colouring
0:09:04 > 0:09:07is due to dust sprayed onto it
0:09:07 > 0:09:09from the tiny moon Phoebe.
0:09:10 > 0:09:12Still mysterious, though,
0:09:12 > 0:09:16is the ridge of ten-mile-high mountains around its equator.
0:09:17 > 0:09:20Weird Hyperion looks like a big sponge
0:09:20 > 0:09:24and is probably more similar to a pile of rubble than a solid moon.
0:09:25 > 0:09:30And finally, there's Enceladus, perhaps the strangest world of all,
0:09:30 > 0:09:33with its fountains of water spewing into space
0:09:33 > 0:09:35and feeding Saturn's E ring.
0:09:36 > 0:09:40The discovery of Enceladus' fountains by Cassini was remarkable
0:09:40 > 0:09:43and it took some plucky flying!
0:09:43 > 0:09:45Something strange had been spotted
0:09:45 > 0:09:48in the magnetic field around the moon's south pole,
0:09:48 > 0:09:51but to investigate this tantalising clue,
0:09:51 > 0:09:55the spacecraft had to go dangerously close to the moon.
0:09:56 > 0:09:58Following up on this hunch
0:09:58 > 0:10:02was the responsibility of Cassini's Michele Dougherty.
0:10:02 > 0:10:04What was it that first made you realise
0:10:04 > 0:10:07Enceladus had something unusual going on?
0:10:07 > 0:10:10The magnetic field looked different. When we looked at the data,
0:10:10 > 0:10:13we could see that it was draping around Enceladus,
0:10:13 > 0:10:16so it was almost as if it wasn't able to go down
0:10:16 > 0:10:19onto the surface of the moon, so something was holding it off.
0:10:19 > 0:10:22There was an obstacle that shouldn't have been there.
0:10:22 > 0:10:24It was almost like there was an atmosphere,
0:10:24 > 0:10:29so we thought we'd be brave and we went to the Cassini project.
0:10:29 > 0:10:31I spoke to the guy responsible for the spacecraft
0:10:31 > 0:10:34and I said, "I want to fly much closer to Enceladus than planned,"
0:10:34 > 0:10:36and he said, "Oh, that's cool!"
0:10:37 > 0:10:42So they changed the third fly-by to be 173 kilometres above the surface,
0:10:42 > 0:10:47and fortuitously, it was going to fly below the south pole.
0:10:47 > 0:10:49And that's when we realised
0:10:49 > 0:10:52that there were actually cracks on the surface,
0:10:52 > 0:10:57which the imaging team called tiger stripes, and out of these cracks,
0:10:57 > 0:11:01water vapour was leaking, and so that was the atmosphere that we had seen.
0:11:01 > 0:11:05So you've got this leaking water. Where it is coming from?
0:11:05 > 0:11:09There's a liquid source underneath the surface,
0:11:09 > 0:11:12a water ocean of some kind.
0:11:12 > 0:11:15Why it's there we don't know, because Enceladus is small.
0:11:15 > 0:11:17It should have cooled down a long time ago,
0:11:17 > 0:11:22so something is keeping its interior warm, but it's not only water.
0:11:22 > 0:11:24We've seen organic material as well.
0:11:24 > 0:11:28Organic means chemicals, complex chemicals with carbon?
0:11:28 > 0:11:33Carbon, nitrogen, methane, benzene.
0:11:33 > 0:11:34All we know is that
0:11:34 > 0:11:37at this little moon that we thought was a dead body,
0:11:37 > 0:11:40there is a liquid reservoir under the surface.
0:11:40 > 0:11:45Dust, water vapour, organic materials are leaking out.
0:11:49 > 0:11:54For me, Titan is the most exiting of Saturn's moons.
0:11:54 > 0:11:57In the 1980s, Voyager, in flying past,
0:11:57 > 0:12:00saw an orange ball with a thick hazy atmosphere
0:12:00 > 0:12:05made up of nitrogen, methane and complex hydrocarbons.
0:12:09 > 0:12:13It has taken Cassini, with some help from its tiny lander Huygens,
0:12:13 > 0:12:17to show us what Titan's surface is really like.
0:12:17 > 0:12:22In January 2005, Huygens was released from the mother spacecraft.
0:12:24 > 0:12:27This descent movie shows it plunging through the atmosphere,
0:12:27 > 0:12:32being buffeted by winds which blow at up to 300 miles an hour.
0:12:33 > 0:12:37On board, a microphone recorded the eerie sound of a moon,
0:12:37 > 0:12:41a billion miles away from those of us listening in on Earth.
0:12:41 > 0:12:44WIND RUSHES
0:12:50 > 0:12:53Finally, Huygens dropped through the clouds
0:12:53 > 0:12:55and was able to see the surface,
0:12:55 > 0:13:00complete with cliffs, rivers and even the shore of an ancient lake.
0:13:00 > 0:13:04When it landed on the surface, it cracked one of the icy pebbles,
0:13:04 > 0:13:05the first example
0:13:05 > 0:13:07of a prang on another world.
0:13:10 > 0:13:12Since then, the Cassini spacecraft
0:13:12 > 0:13:15has been using radar to map the surface.
0:13:15 > 0:13:17Smooth surfaces show up dark,
0:13:17 > 0:13:21so these black and blue areas seem to be liquid of some sort.
0:13:21 > 0:13:25At minus 180 degrees, this can't be water.
0:13:25 > 0:13:28These lakes are made of liquid methane.
0:13:29 > 0:13:32Cassini can also see in infrared,
0:13:32 > 0:13:35picking up the signs of clouds as well as land.
0:13:35 > 0:13:38Titan, it seems, is a complex world,
0:13:38 > 0:13:39just like our own.
0:13:48 > 0:13:51What we've learned about Titan since Cassini arrived
0:13:51 > 0:13:54has transformed our view of this fascinating moon,
0:13:54 > 0:13:57and with us to discuss those new results is Annie Wellbrook.
0:13:57 > 0:13:59- Welcome to the programme.- Thank you.
0:13:59 > 0:14:01What we have here is a beautiful image of Titan,
0:14:01 > 0:14:03but what exactly is it showing?
0:14:03 > 0:14:05This is actually showing the terrain of Titan,
0:14:05 > 0:14:09so we can see the brighter areas are actually high plains of Titan,
0:14:09 > 0:14:12and the darker areas are kind of the surface,
0:14:12 > 0:14:15so all this different terrain, it's actually very similar to Earth.
0:14:15 > 0:14:17If we go to the next image we have,
0:14:17 > 0:14:19we can start to see some of these Earth-like features.
0:14:19 > 0:14:22This is an incredible image. This is presumably a river.
0:14:22 > 0:14:25Yes, absolutely. It's feeding into a lake on the left there.
0:14:25 > 0:14:28You can see how the river is meandering
0:14:28 > 0:14:30and it's just like a river on Earth, really.
0:14:30 > 0:14:33But if we're talking about rain, we're talking about weather,
0:14:33 > 0:14:35so does it change as the seasons change?
0:14:35 > 0:14:38Yes, Cassini has now been in the Saturn system for almost ten years.
0:14:38 > 0:14:41We can now start to observe seasonal changes
0:14:41 > 0:14:43and that's such an exciting thing to do
0:14:43 > 0:14:45because we're realising that, actually,
0:14:45 > 0:14:48the seasonal changes are again similar to Earth's seasonal changes.
0:14:48 > 0:14:52Where does all this methane come from on Titan? What's the source?
0:14:52 > 0:14:54It has been kind of a mystery for a while
0:14:54 > 0:14:57because there's all this methane in the atmosphere
0:14:57 > 0:15:00and it gets broken apart by sunlight. For a long time,
0:15:00 > 0:15:01scientists have thought that
0:15:01 > 0:15:04there must be a source replenishing the methane,
0:15:04 > 0:15:08but actually, there was a recent paper where they talk about
0:15:08 > 0:15:10maybe the methane isn't being replenished,
0:15:10 > 0:15:13and Titan is going to run out of methane
0:15:13 > 0:15:15in tens of millions of years.
0:15:15 > 0:15:16That seems really quick.
0:15:16 > 0:15:19Yeah, in planetary terms that is not a very long time.
0:15:19 > 0:15:22But I really didn't know about this! And I'm really disappointed.
0:15:22 > 0:15:24This is actually really upsetting,
0:15:24 > 0:15:27because I wanted Titan to be a place with methane, with oceans,
0:15:27 > 0:15:31with lakes, with places where life might have even got started.
0:15:31 > 0:15:34People thought of it as a laboratory for the early Earth,
0:15:34 > 0:15:36and now you're telling me that might just be
0:15:36 > 0:15:39the last few tens of millions of years.
0:15:39 > 0:15:40Maybe. At the moment it is a theory,
0:15:40 > 0:15:42and there's still plenty of methane around.
0:15:42 > 0:15:45In your lifetime, it's not going to run out!
0:15:45 > 0:15:47- So don't worry about that. - That's good to know.
0:15:47 > 0:15:49Whether we're down on the surface or up at the top of the atmosphere,
0:15:49 > 0:15:52there's no doubt this is a fascinating world,
0:15:52 > 0:15:54so thank you so much for coming to tell us about it.
0:15:54 > 0:15:55Thank you very much.
0:15:55 > 0:15:57When you think that all we used to know of Titan
0:15:57 > 0:15:58was that it was an orange ball,
0:15:58 > 0:16:02it's now amazing to think what might be going on beneath these clouds.
0:16:02 > 0:16:05Our exploration of Saturn has come to an end
0:16:05 > 0:16:07and we're coming back down to Earth
0:16:07 > 0:16:10to find out about a camera that's being built right here.
0:16:12 > 0:16:14At the Rutherford Appleton Laboratory
0:16:14 > 0:16:18they are getting two very special cameras ready for space,
0:16:18 > 0:16:21and a journey to the International Space Station.
0:16:22 > 0:16:25Looking at Earth is a magical experience.
0:16:25 > 0:16:29You never get tired of an astronaut's view of our home planet.
0:16:31 > 0:16:34There are no space cameras available to the public
0:16:34 > 0:16:37which can see the Earth's surface in detail, until now.
0:16:38 > 0:16:40When fitted, we will be able
0:16:40 > 0:16:42to look at the Earth's surface,
0:16:42 > 0:16:45making out metre-sized objects,
0:16:45 > 0:16:46for the very first time.
0:16:49 > 0:16:52'Called Urthecast, it's a Canadian venture
0:16:52 > 0:16:54'with Russian and British partners,
0:16:54 > 0:16:57'and Tom Morse is the electronic design engineer
0:16:57 > 0:16:59'who's working on the project.'
0:17:01 > 0:17:03Right, so we're here at the entrance to the clean rooms,
0:17:03 > 0:17:06where the cameras are being assembled. In order to go in there,
0:17:06 > 0:17:08we need to get all kitted up in the clean room gear
0:17:08 > 0:17:11to make sure we don't do anything that will contaminate the cameras.
0:17:11 > 0:17:13I feel like I'm being some sort of dinner lady!
0:17:13 > 0:17:16- Right, a face mask here.- Thanks. - So if you hold on to that bit.
0:17:16 > 0:17:18Just pull it over your head.
0:17:21 > 0:17:23Ah-ha, here we have it.
0:17:23 > 0:17:26So here we have the high-resolution Urthecast camera.
0:17:26 > 0:17:28This is going to be mounted on a steerable platform
0:17:28 > 0:17:31on the Russian segment of the International Space Station.
0:17:31 > 0:17:33It's going to be taking video at 3.25 frames a second
0:17:33 > 0:17:36looking down onto Earth and beaming those pictures down to Earth,
0:17:36 > 0:17:38so anybody can access those at home.
0:17:38 > 0:17:41What size of features will this telescope be able to pick out?
0:17:41 > 0:17:45It'll be able to pick out features about 1.1 metres on the ground,
0:17:45 > 0:17:47so you'll be able to see houses,
0:17:47 > 0:17:50you'll be able to see sporting stadiums, you'll be able to see
0:17:50 > 0:17:53natural disasters taking place on the Earth from space.
0:17:53 > 0:17:56What about the other camera? What will that be doing?
0:17:56 > 0:17:58As well as the high-resolution camera,
0:17:58 > 0:18:00we've got what we call the medium-resolution camera,
0:18:00 > 0:18:02and that camera will be pointing
0:18:02 > 0:18:03directly down from the space station,
0:18:03 > 0:18:06scanning across the Earth at 17,000 miles per hour
0:18:06 > 0:18:09and building up strip images of the ground as it passes over.
0:18:09 > 0:18:12And as the Earth rotates underneath that orbit
0:18:12 > 0:18:14it's going to build up a picture of the entire Earth.
0:18:14 > 0:18:16And how frequently will this camera
0:18:16 > 0:18:18be able to build up a complete snapshot of the Earth?
0:18:18 > 0:18:20We're looking at revisiting each spot on the Earth
0:18:20 > 0:18:23about roughly every month, something like that.
0:18:23 > 0:18:25This is a totally new kind of project, isn't it?
0:18:25 > 0:18:28We haven't had these kind of images publicly available before?
0:18:28 > 0:18:31Exactly, so the point of Urthecast is to give everybody on Earth
0:18:31 > 0:18:33the perspective that you can get from the space station.
0:18:33 > 0:18:36People in their armchairs at home are going to be able to log in
0:18:36 > 0:18:39with their laptops or their phones and they'll be able to see
0:18:39 > 0:18:42what an astronaut's-eye view is like from space.
0:18:42 > 0:18:46The cameras go up to the International Space Station in October,
0:18:46 > 0:18:48and I know I'll be giving it a try.
0:18:48 > 0:18:50It's back now to stunning Saturn
0:18:50 > 0:18:53to join Pete and Paul in Hampshire,
0:18:53 > 0:18:55who hope to see it in the night sky.
0:19:09 > 0:19:11'Pete and I have come to Clanfield
0:19:11 > 0:19:14'to visit the Hampshire Astronomical Group,
0:19:14 > 0:19:16'who affectionately call themselves HAGs!'
0:19:18 > 0:19:21The group have a variety of telescopes.
0:19:21 > 0:19:24This one is 117 years old.
0:19:24 > 0:19:27'Graham Bryant helps keep it in fine working order.'
0:19:27 > 0:19:29Hello!
0:19:29 > 0:19:33Oh, wow, look at that. A proper telescope. It's very impressive.
0:19:33 > 0:19:36- This is a refractor. - It is.- What size is this?
0:19:36 > 0:19:37We've got a five-inch Cook refractor
0:19:37 > 0:19:40- and a four-and-a-half-inch Smith, Beck, and Beck.- Wow.
0:19:40 > 0:19:42What sort of focal length are you talking about?
0:19:42 > 0:19:45The Cook is an F17 so it's brilliant for planetary and lunar work.
0:19:45 > 0:19:48And what about this? This looks like the original drive.
0:19:48 > 0:19:50- It is, yes. This is an old weight drive.- Wow.
0:19:50 > 0:19:53I tell the visitors that this was driven by gravity.
0:19:53 > 0:19:57- Is it easy to manoeuvre?- Yes. - Let's have a little...
0:19:57 > 0:20:00- Oh, that's very smooth motion.- Yes.
0:20:00 > 0:20:03See, this is much better than yours, Pete. A proper telescope!
0:20:03 > 0:20:06It's very impressive. What sort of things do you concentrate on here?
0:20:06 > 0:20:10This is used mainly for planetary work, lunar work and solar work.
0:20:10 > 0:20:13Well, it's clearing up nicely up there, so I wouldn't mind
0:20:13 > 0:20:16- having a look at Saturn through this later.- That would be good.
0:20:22 > 0:20:23The sun is setting
0:20:23 > 0:20:27and it's time to brave the elements and set up the telescopes.
0:20:27 > 0:20:30A small group of astronomers have joined us,
0:20:30 > 0:20:33some of whom are new to the wonderful world of Saturn.
0:20:34 > 0:20:37Can you see to that one, or does it need to come lower again?
0:20:37 > 0:20:39A bit lower, please.
0:20:39 > 0:20:41Paul and Olivia live nearby.
0:20:41 > 0:20:44- What have you got in the telescope? - Currently, we're looking at Jupiter.
0:20:44 > 0:20:48- Can I have a look?- Certainly can. - Let's have a look. What have we got?
0:20:48 > 0:20:49That's a lovely image.
0:20:49 > 0:20:53- I see one of the satellites is transiting.- Satellites?
0:20:53 > 0:20:56A satellite is a moon and Jupiter has four really big ones,
0:20:56 > 0:20:58Io, Europa, Ganymede and Callisto,
0:20:58 > 0:21:01and if you have a look through the telescope, what can you see?
0:21:02 > 0:21:06There are two moons to the right of Jupiter,
0:21:06 > 0:21:08but because this is reversed
0:21:08 > 0:21:10and it's back-to-front,
0:21:10 > 0:21:13it looks like it's at the bottom, but it's at the top.
0:21:13 > 0:21:15Pete Lawrence, the fountain of all knowledge and wisdom,
0:21:15 > 0:21:17has just informed me it's Callisto,
0:21:17 > 0:21:19so that's one of the moons passing over.
0:21:19 > 0:21:21- Quite pretty, isn't it?- Yeah.
0:21:21 > 0:21:24Hopefully, later on, Saturn will be rising over there in the east,
0:21:24 > 0:21:26so we can have a look at it,
0:21:26 > 0:21:29and your telescope should bring out some nice details, I think.
0:21:29 > 0:21:32For Christina, Saturn is one planet
0:21:32 > 0:21:35she has been looking forward to getting in her viewfinder.
0:21:35 > 0:21:38- Christina!- Hello!- Hello again, hi.
0:21:38 > 0:21:39What are you looking at? The moon?
0:21:39 > 0:21:42I'm looking at the moon, yes, big and bright.
0:21:42 > 0:21:44It's actually first quarter at the moment,
0:21:44 > 0:21:47so that shadow line is right the way down the middle of the moon.
0:21:47 > 0:21:50- Have you had a chance to get out and see Saturn?- I have.- You have?
0:21:50 > 0:21:52- I've seen it for the first time. - Wow. What was your reaction?
0:21:52 > 0:21:55- Wow!- Yeah, it is, isn't it?
0:21:55 > 0:21:58I mean, it was teeny tiny, but still wow.
0:21:58 > 0:22:02Becky is new to astronomy and really enjoying it.
0:22:02 > 0:22:04- Becky, welcome to The Sky At Night. - Thank you.
0:22:04 > 0:22:08- You're an absolute beginner, aren't you?- Total absolute beginner, yeah.
0:22:08 > 0:22:10What sort of things have you been looking at?
0:22:10 > 0:22:13I've been looking at Jupiter as that's the easiest to find in the sky
0:22:13 > 0:22:15and I remember seeing Jupiter for the first time through it
0:22:15 > 0:22:18and it was like, "Wow, that's absolutely amazing."
0:22:18 > 0:22:20Have you had any luck with anything else?
0:22:20 > 0:22:23I'm hoping to see Saturn tonight, that's kind of on my tick list today.
0:22:23 > 0:22:25- Fingers crossed for clear skies! - Thank you very much.
0:22:25 > 0:22:27- Let's hope for the best.- Thank you.
0:22:37 > 0:22:38With a small telescope,
0:22:38 > 0:22:41you can see Saturn and its rings and some of the moons,
0:22:41 > 0:22:44but with a bigger one, you can see much more detail
0:22:44 > 0:22:46such as the subtle banding on the planet.
0:22:46 > 0:22:48Its rings have features too -
0:22:48 > 0:22:50the outer A ring, then a gap
0:22:50 > 0:22:52called the Cassini Division,
0:22:52 > 0:22:53and then the inner B ring.
0:22:53 > 0:22:55Yeah, I thought it would be a bit of a blur,
0:22:55 > 0:22:57but you can actually see everything.
0:22:57 > 0:23:00- Yeah.- You can see the rings and... - Yeah. Yes.
0:23:00 > 0:23:02Tonight, with Saturn so low down,
0:23:02 > 0:23:04it's going to be tough to see that detail.
0:23:04 > 0:23:06Ah, Olivia, you're looking through the telescope.
0:23:06 > 0:23:09That's what I like to see. What are you looking at?
0:23:09 > 0:23:10I'm looking at a picture of Saturn.
0:23:10 > 0:23:12So what do you think of it as a planet?
0:23:14 > 0:23:16It's quite nice with the rings.
0:23:16 > 0:23:22- You can see the divisions, and you can see the moons.- Yeah?
0:23:22 > 0:23:25When you're looking at the rings, so you've got the planet in the middle
0:23:25 > 0:23:29and you've got the rings that go around them, so you can see the gap
0:23:29 > 0:23:31- between the rings and the planet, you can see that?- Yeah.
0:23:31 > 0:23:36Can you see in the rings that there is a sort of dark line
0:23:36 > 0:23:38running around between the rings,
0:23:38 > 0:23:40sort of dividing them up?
0:23:40 > 0:23:43- It's not easy to see. - Sort of.- Sort of?
0:23:43 > 0:23:46Keep a look out for it, and it will get better.
0:23:46 > 0:23:48So, we're with Becky
0:23:48 > 0:23:51- and you've done something brand-new tonight, haven't you?- Yes, I have.
0:23:51 > 0:23:53- Go on, tell them. Tell them! - It's totally amazing.
0:23:53 > 0:23:56- I have actually found Saturn through my telescope.- Hurray!
0:23:56 > 0:23:57- Well done!- Brilliant!
0:23:57 > 0:24:00You've got your little three-inch telescope here.
0:24:00 > 0:24:01It's obviously Saturn, isn't it?
0:24:01 > 0:24:04With the rings and the satellite, so you must be very proud.
0:24:04 > 0:24:07Yeah, I'm really proud. It took me a while, but I'm so excited
0:24:07 > 0:24:09that I found it. It's absolutely brilliant.
0:24:09 > 0:24:12You have to be patient when looking at the planets,
0:24:12 > 0:24:15especially Saturn with its gentle pastel colouring.
0:24:15 > 0:24:18Keep looking through the eyepiece and that detail should emerge.
0:24:18 > 0:24:21- Come and have a look at this.- OK.
0:24:21 > 0:24:23Your perseverance will pay off.
0:24:23 > 0:24:29Oh, yeah. You can start to see the shadows on the globe now.
0:24:29 > 0:24:33If you'd like to find Saturn in May's night sky, go to our website.
0:24:38 > 0:24:40Pete has some helpful star charts.
0:24:40 > 0:24:44There are some nice globular clusters such as M13.
0:24:44 > 0:24:46You'll find charts for those too.
0:24:46 > 0:24:48Yeah. That's amazing.
0:24:48 > 0:24:51- Beautiful, isn't it?- Wonderful.
0:24:52 > 0:24:57We have one more chance to see Saturn with the old telescope.
0:24:57 > 0:25:01- Hello there.- We thought we'd come back for a final view of Saturn
0:25:01 > 0:25:04through this magnificent antique piece of yours.
0:25:04 > 0:25:06Well, it's a very nice, steady view at the moment.
0:25:06 > 0:25:09- Do you want to take a look, Pete? - I'd love to have a look.
0:25:09 > 0:25:12- Go on, you go first.- This is 117 years old, this telescope.
0:25:12 > 0:25:13- Yes.- That's incredible.
0:25:13 > 0:25:17It looks so beautiful, doesn't it, in this light?
0:25:17 > 0:25:19- Oh, that's just gorgeous. - Is it a good view?
0:25:19 > 0:25:22It's absolutely beautiful. That's the classic view
0:25:22 > 0:25:24that looks as if someone's cut out a picture of Saturn
0:25:24 > 0:25:27- and stuck it on the front of the telescope.- Absolutely.
0:25:27 > 0:25:29- Let's have a look. - It's lovely, absolutely beautiful.
0:25:29 > 0:25:30And where's the focusing?
0:25:30 > 0:25:33Ah, there it is. So let's have a look. What have we got?
0:25:33 > 0:25:35Oh, my word, look at that.
0:25:35 > 0:25:37That is a magnificent view. I have to say,
0:25:37 > 0:25:40I think this is better than the view in your 24-inch.
0:25:40 > 0:25:42The magic is always there.
0:25:42 > 0:25:46Spectacular Saturn, out amongst the stars of Virgo.
0:25:46 > 0:25:47Well, thanks, Graham,
0:25:47 > 0:25:50for showing us Saturn in this beautiful constructed telescope.
0:25:50 > 0:25:53I think it's been one the best views of Saturn for a long time.
0:25:53 > 0:25:57- Thank you very much, Graham. That was brilliant.- You're both welcome.
0:26:00 > 0:26:04Well, weren't Pete and Paul lucky to get such good weather?
0:26:04 > 0:26:06Let's hope we have clear skies this month too.
0:26:06 > 0:26:08The Sky At Night's Space Surgery
0:26:08 > 0:26:10has been receiving lots and lots of your queries,
0:26:10 > 0:26:12and on call this month, as ever, Chris North.
0:26:12 > 0:26:15- Chris, what have you got for us? - We've had a lot of questions
0:26:15 > 0:26:18and our first one this month refers to the planet Saturn,
0:26:18 > 0:26:20that we've talked about for most of the programme.
0:26:20 > 0:26:23Coming in from James Coyle, aged five, from Northern Ireland,
0:26:23 > 0:26:24who asks...
0:26:27 > 0:26:30James, although Saturn is the planet that's by far the most famous
0:26:30 > 0:26:32for its beautiful ring system,
0:26:32 > 0:26:35the other planets, Jupiter, Uranus and Neptune, the large planets,
0:26:35 > 0:26:38do in fact have ring systems.
0:26:38 > 0:26:40They're very hard to detect, they're very faint,
0:26:40 > 0:26:43and they've only been discovered in the last few decades.
0:26:43 > 0:26:46Chris, our next question is for you. It refers to last month's programme.
0:26:46 > 0:26:49It comes in from Kevin Geary, and many others,
0:26:49 > 0:26:52who've asked about that rock you were holding
0:26:52 > 0:26:53that you claimed was from Mars.
0:26:57 > 0:26:58People should just believe me.
0:26:58 > 0:27:01I think that's the easy way, but actually, the reason we know
0:27:01 > 0:27:04this particular rock was from Mars is, we have sort of been there.
0:27:04 > 0:27:05We've sent probes there,
0:27:05 > 0:27:08and in particular, the Viking probes in the '70s
0:27:08 > 0:27:12told us about the chemical composition of the Martian rocks
0:27:12 > 0:27:13and, in fact, the atmosphere.
0:27:13 > 0:27:17So when we find that composition in a meteorite that's landed on Earth,
0:27:17 > 0:27:21we are able to say yes, this definitely isn't Earthly,
0:27:21 > 0:27:22this rock comes from Mars.
0:27:22 > 0:27:26And they're precious because these are the only samples we get back,
0:27:26 > 0:27:29so until we go to Mars and pick some up, we need these meteorites,
0:27:29 > 0:27:31but we can be sure they're from Mars.
0:27:31 > 0:27:33And, Lucie, finally, last one is for you.
0:27:33 > 0:27:36It refers to the gas giants again,
0:27:36 > 0:27:38so Jupiter and also Saturn have atmospheres
0:27:38 > 0:27:40of mainly hydrogen and helium.
0:27:40 > 0:27:42Audrey Michie from Turriff asks...
0:27:45 > 0:27:47So as the meteor comes in,
0:27:47 > 0:27:49it does indeed burn up as it goes through the atmosphere,
0:27:49 > 0:27:52but even though hydrogen is very explosive, for example,
0:27:52 > 0:27:55if I had a balloon full of hydrogen and I put a flame to it,
0:27:55 > 0:27:57it would explode and make a huge bang.
0:27:57 > 0:28:02We also use hydrogen to get rockets into space because we burn it,
0:28:02 > 0:28:04and there is no oxygen in these planets
0:28:04 > 0:28:08to allow the hydrogen to burn, so that's why it doesn't set light.
0:28:08 > 0:28:09Lucky for the planets, I guess,
0:28:09 > 0:28:11otherwise it would be a very big fireball!
0:28:11 > 0:28:14Keep your questions about this programme
0:28:14 > 0:28:16or in fact anything to do with astronomy coming in.
0:28:16 > 0:28:18You can do that at our website...
0:28:21 > 0:28:24We look forward to the challenges you'll set us.
0:28:24 > 0:28:27Yes, do try to catch Chris out. But when we come back next month,
0:28:27 > 0:28:30we'll be talking about the lives of the stars. So until then...
0:28:30 > 0:28:32ALL: Good night.
0:28:48 > 0:28:52Subtitles by Red Bee Media Ltd