0:00:34 > 0:00:37- BOTH: Hello.- Welcome to the Natural History Museum
0:00:37 > 0:00:38here in London.
0:00:38 > 0:00:42This is the Otumpa meteorite, a piece of space that fell to Earth.
0:00:42 > 0:00:45When I first came here as a small boy I ran through the gallery to try
0:00:45 > 0:00:48and get close to it. I am still impressed today.
0:00:48 > 0:00:50This programme is all about meteorites.
0:00:50 > 0:00:53We've come to see the museum's fantastic collection of space rocks
0:00:53 > 0:00:56and find out what we're still learning about them today.
0:00:56 > 0:01:00We'll bring you the latest on the Chelyabinsk impact in Russia,
0:01:00 > 0:01:04and Jon Culshaw has been on a meteorite hunt of his own in Wiltshire.
0:01:04 > 0:01:07Pete and Paul have tips on what to see in this month's night sky,
0:01:07 > 0:01:11and Chris North has something new - our first Space Surgery.
0:01:13 > 0:01:17Seeing any fireball falling to Earth is very special.
0:01:17 > 0:01:20ALL: Wow!
0:01:20 > 0:01:22What a corker!
0:01:22 > 0:01:26Meteorites are essentially space rocks that are unlucky enough
0:01:26 > 0:01:27to collide with Earth.
0:01:27 > 0:01:33Last month, asteroid 2012 DA14 had a lucky escape, swinging past
0:01:33 > 0:01:37close enough for Sky At Night viewers to capture these amazing images.
0:01:42 > 0:01:43Most meteorites are small
0:01:43 > 0:01:46and the product of a collision between asteroids
0:01:46 > 0:01:51resulting in millions of tiny, rocky fragments which float in space.
0:01:51 > 0:01:55Some get in our way and then burn up in the Earth's atmosphere,
0:01:55 > 0:01:58sometimes creating a fireball and sometimes landing on Earth.
0:02:02 > 0:02:03ALL: Oh!
0:02:03 > 0:02:06But meteorites can come from all sorts of places,
0:02:06 > 0:02:10sometimes from comets and sometimes even from other planets.
0:02:13 > 0:02:15Meteorites are our best way of getting ahold
0:02:15 > 0:02:19of a piece of another world and looking at it close-up.
0:02:21 > 0:02:24The Natural History Museum has one of the finest collections
0:02:24 > 0:02:26anywhere in the world.
0:02:26 > 0:02:28This is just fabulous.
0:02:28 > 0:02:33This is an enormous piece of Mars that fell to Earth in 2011.
0:02:33 > 0:02:36That impact was observed and this is a fresh Martian meteorite,
0:02:36 > 0:02:40kept in this case to keep it away from Earthly contamination.
0:02:40 > 0:02:44That means it can tell us stories of the Red Planet
0:02:44 > 0:02:47and this particular rock is the only Martian meteorite to show
0:02:47 > 0:02:52signs of water, weathering it away in the dim and distant past on Mars.
0:02:57 > 0:03:01These are the latest images from our rovers on Mars
0:03:01 > 0:03:03and their self-portraits show them hard at work
0:03:03 > 0:03:05on the surface of the Red Planet.
0:03:05 > 0:03:09Even though they're doing amazing science, nothing beats getting
0:03:09 > 0:03:12hold of a lump of Mars and bringing it down into the lab.
0:03:14 > 0:03:18700,000 years ago, an impact on Mars resulted in debris
0:03:18 > 0:03:20being flung into space.
0:03:24 > 0:03:28What became the Tissint meteorite wandered through space before falling
0:03:28 > 0:03:33down to Earth, providing us with a hands-on guide to Mars' past.
0:03:35 > 0:03:39At the Natural History Museum, they're using medical CT scanning
0:03:39 > 0:03:44technology to build up an image of Tissint and its insides.
0:03:44 > 0:03:47They're looking for holes or voids inside the rock
0:03:47 > 0:03:50which could be filled with Martian air.
0:03:54 > 0:03:58This is a CT scan of a small fragment of Tissint
0:03:58 > 0:04:01that I looked at last year in the summer.
0:04:01 > 0:04:04'Caroline Smith is the meteorite curator.'
0:04:04 > 0:04:05Just to give you an idea,
0:04:05 > 0:04:08it is about the size of the end of my little finger.
0:04:08 > 0:04:09Quite a small thing.
0:04:09 > 0:04:12What we're seeing here is a video, a movie
0:04:12 > 0:04:14as if we're sort of flying through the specimen.
0:04:14 > 0:04:19'The CT scan has revealed a hole in Tissint which is filled with air.'
0:04:19 > 0:04:22The question is, if this has got air in it,
0:04:22 > 0:04:24is it Earth air or Martian air?
0:04:24 > 0:04:27If it is completely sealed in the rock,
0:04:27 > 0:04:30theoretically it still should have Martian air in it.
0:04:30 > 0:04:32That's what we wanted to find out.
0:04:32 > 0:04:35You can see it is completely sealed at this end.
0:04:35 > 0:04:38Oh, but hang on, we've got all of this red stuff here
0:04:38 > 0:04:40- and in fact, there is a little hole.- Oh, no!
0:04:40 > 0:04:43Yeah, so if there was any Martian atmosphere in there,
0:04:43 > 0:04:45it ain't there now!
0:04:45 > 0:04:47We wouldn't have been able to do this a few years ago.
0:04:47 > 0:04:49With this, we can get a really good
0:04:49 > 0:04:53idea of what's inside the meteorite without having to chop it up,
0:04:53 > 0:04:55without having to cut it, without having to break it.
0:04:55 > 0:04:58Whenever you do those to any samples, but especially
0:04:58 > 0:04:59rare meteorites, of course,
0:04:59 > 0:05:01you're damaging something rare and precious.
0:05:03 > 0:05:06Meteorites are classified by their composition.
0:05:06 > 0:05:09Some are made of stone, but some are made of iron,
0:05:09 > 0:05:13the condensed cores of what must have been larger asteroids.
0:05:13 > 0:05:15Some are mixtures of both.
0:05:17 > 0:05:20The most interesting meteorites are relics of a time nearly
0:05:20 > 0:05:25five billion years ago, when our solar system was just forming.
0:05:25 > 0:05:29Out of the dust and debris left over from the birth of our sun,
0:05:29 > 0:05:31planets were eventually formed.
0:05:31 > 0:05:36But the details are sketchy and what we need is first-hand evidence.
0:05:36 > 0:05:38We get just that in the form of meteorites
0:05:38 > 0:05:41called carbonaceous chondrites,
0:05:41 > 0:05:45the fossilised remains of the primeval solar system.
0:05:48 > 0:05:51So, we're in the carbonaceous chondrite drawer.
0:05:51 > 0:05:53You can see there's lots of different labels.
0:05:53 > 0:05:57What do they look like? How would we know one if it landed in the back garden?
0:05:57 > 0:06:00They're actually quite boring-looking rocks, actually.
0:06:00 > 0:06:01But that's the thing.
0:06:01 > 0:06:05Their lack of looking interesting belies their significance
0:06:05 > 0:06:08because they're actually some of the most interesting
0:06:08 > 0:06:11meteorites that we actually have to study. This is called Allende.
0:06:11 > 0:06:16Why Allende is very important is primarily because of these things.
0:06:16 > 0:06:20You can see on the surface of this one is this white splodge.
0:06:20 > 0:06:24And then you can see inside as well, there's lots of sort of smaller,
0:06:24 > 0:06:26irregularly shaped white objects.
0:06:26 > 0:06:29These are these things called CAIs,
0:06:29 > 0:06:32stands for calcium aluminium-rich inclusion.
0:06:32 > 0:06:36And the CAIs, we think, are the first solid objects to form
0:06:36 > 0:06:37in our solar system.
0:06:37 > 0:06:42When we talk about the solar system being 4.6 billion years,
0:06:42 > 0:06:44it's actually dating the CAIs
0:06:44 > 0:06:48and in fact, we think in the very, very early solar system,
0:06:48 > 0:06:51in this protoplanetary disc, that's where these rocks
0:06:51 > 0:06:54were beginning to form by bits and pieces all sticking together.
0:06:56 > 0:06:59Another reason why carbonaceous chondrites are particularly
0:06:59 > 0:07:03interesting is because some of them are very rich in organic molecules.
0:07:03 > 0:07:06Right, there is a story about this, isn't there? Is it the Murchison one?
0:07:06 > 0:07:10That's right, the Murchison is one of my favourite meteorites.
0:07:10 > 0:07:13That means it's smelly. That's what I have heard anyway.
0:07:13 > 0:07:14Murchison is smelly.
0:07:16 > 0:07:19Oh, yeah, you get a really strong gunpowder smell out of it.
0:07:19 > 0:07:21It's quite amazing, so I will try...
0:07:21 > 0:07:24And that's been given off by the meteorite?
0:07:24 > 0:07:26This has been given off by the meteorite.
0:07:26 > 0:07:29Now, I will sort of take it out, hopefully no bits will drop off!
0:07:29 > 0:07:32It's quite fragile. So this is a fairly large piece.
0:07:32 > 0:07:35This one weighs about 800 grams.
0:07:35 > 0:07:39You can hold it but very carefully, because it is quite friable.
0:07:39 > 0:07:41And you can see again, a bit like Allende,
0:07:41 > 0:07:44quite a boring-looking meteorite, but it is very, very,
0:07:44 > 0:07:47very rich in organic molecules - amino acids,
0:07:47 > 0:07:51sugars and perhaps the most interesting, I think,
0:07:51 > 0:07:55are nuclear bases, because nuclear bases are the organic molecules
0:07:55 > 0:07:57you need for DNA to replicate.
0:07:57 > 0:07:59I was going to say, these are complicated molecules.
0:07:59 > 0:08:01These are complicated molecules.
0:08:02 > 0:08:06Asteroids and comets carry in them the building blocks of life,
0:08:06 > 0:08:08which then fall to Earth in meteorites.
0:08:10 > 0:08:14They have a sinister presence, emerging from the blackness
0:08:14 > 0:08:17and then disappearing silently again.
0:08:17 > 0:08:20They're dark, cratered worlds, scarred by impacts -
0:08:20 > 0:08:23most ancient, but some quite recent.
0:08:25 > 0:08:27Tracked by telescopes,
0:08:27 > 0:08:29we know precisely where the large ones are,
0:08:29 > 0:08:33but the vast majority of asteroids are too small for us to detect
0:08:33 > 0:08:34until the last minute.
0:08:37 > 0:08:41A fireball is the only sign that something's on the way.
0:08:43 > 0:08:47The last meteorite to fall in the UK was in 1991.
0:08:47 > 0:08:50In that typically understated British way,
0:08:50 > 0:08:52it didn't make much of a fuss
0:08:52 > 0:08:54when it landed in Mr Pettifor's garden, near Cambridge.
0:08:56 > 0:09:00They heard a whistling noise and the neighbour said,
0:09:00 > 0:09:03"Arthur, I think something's just landed in your garden."
0:09:03 > 0:09:08Right at the back of the garden they found this dark rock sitting
0:09:08 > 0:09:10where there had been no dark rock,
0:09:10 > 0:09:13and Mr Pettifor was clever enough to realise that this was
0:09:13 > 0:09:16something quite unusual and maybe this was a meteorite.
0:09:16 > 0:09:18You get lots of these calls
0:09:18 > 0:09:20from people who think they've found meteorites.
0:09:20 > 0:09:22A few hundred a year, yes!
0:09:22 > 0:09:25So when you go out to chase one of these up -
0:09:25 > 0:09:28the story sounds convincing - but what do you look for in the rock?
0:09:28 > 0:09:30The first thing that's very characteristic
0:09:30 > 0:09:32is the very, very dark crust.
0:09:32 > 0:09:36- Burnt is the wrong word... - Well, it's melted rock.
0:09:36 > 0:09:40It's called the fusion crust, so as this meteorite was hurtling through
0:09:40 > 0:09:41Earth's atmosphere,
0:09:41 > 0:09:44the rock actually melts, but only on the outside.
0:09:44 > 0:09:47The inside never gets hot enough to melt.
0:09:48 > 0:09:51I'm going to give away a little secret here.
0:09:51 > 0:09:54One of the ways that we filter calls when people say,
0:09:54 > 0:09:56"A meteorite landed in my garden last night,"
0:09:56 > 0:09:59we always say to them, "What happened? Was it hot when you picked it up?"
0:09:59 > 0:10:02As soon as they say, "Yes, it was boiling hot,"
0:10:02 > 0:10:04or, "It set the grass on fire," or whatever,
0:10:04 > 0:10:06then it's not a meteorite
0:10:06 > 0:10:08because the very few occasions, I should say,
0:10:08 > 0:10:12where meteorites have landed and somebody has picked them up
0:10:12 > 0:10:16almost immediately afterwards, they are described as being "lukewarm."
0:10:18 > 0:10:20Well, this is the last British meteorite,
0:10:20 > 0:10:24but of course, we've had the Russian meteorite in Chelyabinsk, which was very exciting.
0:10:24 > 0:10:25What do we know about that?
0:10:25 > 0:10:28The best guesstimate at the moment for the size of the object
0:10:28 > 0:10:31when it came into the Earth's atmosphere
0:10:31 > 0:10:33is about 17 metres wide.
0:10:33 > 0:10:35What sort of percentage survives to the ground?
0:10:35 > 0:10:37Well, it's difficult to say,
0:10:37 > 0:10:42but you might lose at least half the pre-atmospheric mass and size...
0:10:42 > 0:10:44Thousands of stones have already been recovered
0:10:44 > 0:10:47and the largest one, I think, is about two kilograms.
0:10:47 > 0:10:51Is there scientific value in getting it so soon after an impact?
0:10:51 > 0:10:53Oh, absolutely.
0:10:53 > 0:10:56The less time a meteorite is sitting around on the ground for,
0:10:56 > 0:10:58the less it is being contaminated.
0:11:02 > 0:11:05More than 1,000 meteorites fall to Earth every year.
0:11:08 > 0:11:11Caroline regularly goes meteorite hunting in the desert,
0:11:11 > 0:11:14where conditions are ideal for preserving them.
0:11:14 > 0:11:19In 2010 in Australia, she found a funny little rock,
0:11:19 > 0:11:22which at first glance, looked nothing special.
0:11:22 > 0:11:25Lucy is meeting up with Anton Kearsley
0:11:25 > 0:11:27in the basement of the museum.
0:11:27 > 0:11:30He used his electron microscope to look at Caroline's find
0:11:30 > 0:11:33and was amazed at what he found.
0:11:33 > 0:11:39It was something incredibly rare - a meteorite from the moon.
0:11:39 > 0:11:43This is an image of a cutaway of the meteorite,
0:11:43 > 0:11:46- magnified by a certain number of times.- That's right.
0:11:46 > 0:11:48On the screen at the moment, it is about 300 times magnification.
0:11:48 > 0:11:50On the picture over here,
0:11:50 > 0:11:53you can see that the whole thing is just over a centimetre in size.
0:11:53 > 0:11:56It's about a fingernail size.
0:11:57 > 0:12:00And this is a really curious little area.
0:12:01 > 0:12:04Because there's a little dark grey patch
0:12:04 > 0:12:08with some little pale grey patches inside it.
0:12:08 > 0:12:11And when you start analysing the pale grey patches,
0:12:11 > 0:12:15these ones turn out to have a very interesting chemical composition.
0:12:15 > 0:12:18It turns out to be quite unlike the composition of things
0:12:18 > 0:12:20- that we find on Earth.- OK.
0:12:21 > 0:12:24This is a little mineral again, silicate mineral
0:12:24 > 0:12:27but now it's got a lot of very strange elements in it.
0:12:27 > 0:12:30It's got zirconium, and yttrium
0:12:30 > 0:12:32and titanium and iron and silicon,
0:12:32 > 0:12:35it's actually quite well-known,
0:12:35 > 0:12:38but it's called tranquillityite.
0:12:39 > 0:12:42The Mare Tranquillitatis -
0:12:42 > 0:12:44one of the most famous features on the moon
0:12:44 > 0:12:46and where man first stood.
0:12:46 > 0:12:49These precious meteorites give us
0:12:49 > 0:12:53clues about the moon's ancient past and how it's changed,
0:12:53 > 0:12:58which is why finding them in pristine condition is so important.
0:12:58 > 0:13:01On Earth, deserts hot and cold
0:13:01 > 0:13:05are ideal for preserving these extraterrestrial rocks.
0:13:05 > 0:13:10The Antarctic has become the new Mecca for meteorite hunters.
0:13:10 > 0:13:13Since 1976, ANSMET,
0:13:13 > 0:13:17the US Antarctic Search for Meteorites program
0:13:17 > 0:13:21has retrieved 20,000 meteorites.
0:13:21 > 0:13:25Lunar scientist Katie Joy spent two months in Antarctica
0:13:25 > 0:13:28and her group managed to collect 63 meteorites,
0:13:28 > 0:13:31but they were hampered by the wind
0:13:31 > 0:13:35and temperatures of -25 degrees centigrade.
0:13:35 > 0:13:36Katie returned in January
0:13:36 > 0:13:39and to remind her of her Antarctic experiences
0:13:39 > 0:13:44we took her to a bar in central London made completely of ice
0:13:44 > 0:13:47and it was a balmy -5 degrees centigrade.
0:13:47 > 0:13:52It's only -5 in here, it was -25 in Antarctica! This is easy!
0:13:52 > 0:13:57So, Katie, why go to the extreme of visiting Antarctica
0:13:57 > 0:14:00- to look for your meteorites? - Antarctica's a desert.
0:14:00 > 0:14:02It has very little rainfall and precipitation,
0:14:02 > 0:14:05which means that the meteorites that are found there
0:14:05 > 0:14:06are very well preserved.
0:14:06 > 0:14:08Also there are no trees, no buildings...
0:14:08 > 0:14:13It's easy to find a nice big black meteorite sitting on the white ice,
0:14:13 > 0:14:15so it's kind of an easy thing to do.
0:14:15 > 0:14:17This is a good example of the dark meteorites
0:14:17 > 0:14:19that would be sitting on the ice.
0:14:19 > 0:14:23Are there particularly good places to look for meteorites on Antarctica?
0:14:23 > 0:14:24There are.
0:14:24 > 0:14:28Meteorites fall randomly all over Antarctica as they do the rest of the world,
0:14:28 > 0:14:31but what happens is that the ice on the polar plateau
0:14:31 > 0:14:34flows out towards the edge of the continent
0:14:34 > 0:14:37and when it hits the mountain ranges,
0:14:37 > 0:14:38the ice is brought up to the surface
0:14:38 > 0:14:42and so we find natural concentration sites,
0:14:42 > 0:14:44typically along the big mountain ranges,
0:14:44 > 0:14:46such as the Transantarctic Mountains.
0:14:46 > 0:14:48It's cold enough being in here,
0:14:48 > 0:14:50working in Antarctica
0:14:50 > 0:14:53must have been incredibly challenging. Tell me about your experience.
0:14:53 > 0:14:56I was there for six weeks on the ice, a very remote area,
0:14:56 > 0:14:59and every day we'd get up and if the weather was good enough
0:14:59 > 0:15:00we would go out and search.
0:15:00 > 0:15:03Sometimes if you have a lot of snow or it's very windy -
0:15:03 > 0:15:05Antarctica's completely unpredictable -
0:15:05 > 0:15:08you get stuck in the tent which is frustrating,
0:15:08 > 0:15:10cos all you want to do is go out and find more meteorites.
0:15:10 > 0:15:13It's hard work, but when you find them, it's a great award.
0:15:14 > 0:15:18Antarctica is still a rich source of meteorites
0:15:18 > 0:15:21with more science visits planned in the future.
0:15:21 > 0:15:25Every meteorite, it seems, has a story of its own.
0:15:29 > 0:15:32This is the largest meteorite in the museum's collection from Cranborne
0:15:32 > 0:15:35in Australia and at three-and-a-half tons,
0:15:35 > 0:15:38it weighs the same as four cars.
0:15:38 > 0:15:41It's an impressive beast and it is older than the Earth.
0:15:41 > 0:15:44But, we have some impressive meteorites in Britain too
0:15:44 > 0:15:46and Jon has been on the trail of one of them.
0:15:46 > 0:15:50This one may have been carried along by a glazier and it even
0:15:50 > 0:15:52attracted the interest of prehistoric man,
0:15:52 > 0:15:56but it was rediscovered sitting on someone's doorstep.
0:15:59 > 0:16:04This is the Iron Age hill fort at Barbury Castle near Swindon,
0:16:04 > 0:16:07first occupied some 2,500 years ago.
0:16:11 > 0:16:16And what a wonderfully atmospheric and peaceful place this is.
0:16:16 > 0:16:19There's a real air of mystery around here.
0:16:19 > 0:16:23And all around you can see the remnants of the influence
0:16:23 > 0:16:27of ancient man - this Iron Age fort, burial mounds, and it brings to mind
0:16:27 > 0:16:31those stories of those Victorian amateur archaeologists who used
0:16:31 > 0:16:36to love to explore and dig things up and whatever they found fascinating
0:16:36 > 0:16:39or just liked the look of, they would take home to their collections.
0:16:41 > 0:16:46This old photograph from Country Life in 1908 is of the Lake House mansion
0:16:46 > 0:16:50in Wiltshire, once owned by the Rev Edward Duke.
0:16:50 > 0:16:54He was known to excavate local burial grounds,
0:16:54 > 0:16:57keeping any interesting pieces for his own private collection.
0:16:57 > 0:17:01On the doorstep is certainly something very interesting.
0:17:01 > 0:17:02It's the Lake House meteorite.
0:17:03 > 0:17:07Here at the Salisbury and South Wiltshire Museum,
0:17:07 > 0:17:10I met up with Professor Colin Pillinger.
0:17:10 > 0:17:13'He's become a meteorite detective and he's been piecing together
0:17:13 > 0:17:16'the history of the Lake House meteorite.'
0:17:18 > 0:17:23- Ah! There it is. The Lake House meteorite.- Indeed. You can't miss it.
0:17:23 > 0:17:26- It's a fair size, isn't it?- Well,
0:17:26 > 0:17:29- it is 92.5 kilograms.- Wow!
0:17:29 > 0:17:31But this is not only the BIGGEST British meteorite that we
0:17:31 > 0:17:36know about, it is also the one that has been longest on Earth
0:17:36 > 0:17:39and it was when we made that measurement that all of us
0:17:39 > 0:17:41suddenly realised we had something quite exciting.
0:17:41 > 0:17:44So how old exactly is this meteorite
0:17:44 > 0:17:47and how long has it been on the Earth?
0:17:47 > 0:17:50It's technically 4.5, 4.6 billion years old.
0:17:50 > 0:17:53It's been on Earth 32,000 years
0:17:53 > 0:17:57but to try and explain how it survived 32,000 years,
0:17:57 > 0:18:00you have to tease some facts out of it.
0:18:00 > 0:18:0332,000 years ago on Salisbury Plain,
0:18:03 > 0:18:05the place was covered in ice.
0:18:05 > 0:18:09We're confident that we know meteorites survive very well in ice,
0:18:09 > 0:18:13because we collect lots of meteorites on Antarctica.
0:18:13 > 0:18:15How do you explain the next bit?
0:18:15 > 0:18:18Bronze Age people living on Salisbury Plain,
0:18:18 > 0:18:21sort of 4,000 years ago
0:18:21 > 0:18:26were building mounds to bury their important people.
0:18:26 > 0:18:29The meteorite was then put into one of these barrows.
0:18:29 > 0:18:32The majority of the rock that they used would have been chalk.
0:18:32 > 0:18:36You've these lovely pictures of the meteorite on the step, you see
0:18:36 > 0:18:39the patches of chalk still on the meteorite,
0:18:39 > 0:18:44so it clearly was packed somewhere closely associated with chalk.
0:18:44 > 0:18:48Colin believes that after it was dug up, the meteorite must have
0:18:48 > 0:18:51been kept inside, protected in Edward Duke's collection.
0:18:51 > 0:18:55But after his death, it was demoted to the doorstep,
0:18:55 > 0:18:59possibly used for kicking off mud from gentlemen's boots.
0:18:59 > 0:19:03Since then the chalk has washed off and you look at the meteorite now
0:19:03 > 0:19:05and there's no chalk there.
0:19:05 > 0:19:09So it can't have been out on that step for more than about 100 years.
0:19:09 > 0:19:15So the story goes, 32,000 years ago, a meteorite fell in Britain
0:19:15 > 0:19:17and was preserved in a glacier.
0:19:17 > 0:19:21Then, used by Bronze Age man to build his burial mound
0:19:21 > 0:19:24and dug up by a Victorian archaeologist.
0:19:24 > 0:19:28Using a series of clues, Colin has revealed an extraordinary tale
0:19:28 > 0:19:31about an extraordinary meteorite.
0:19:32 > 0:19:35A wonderful piece of serendipity.
0:19:35 > 0:19:38- The needle left the haystack and made its way to you.- Absolutely.
0:19:38 > 0:19:41Science is a lot of serendipity.
0:19:41 > 0:19:43Such good fun.
0:19:47 > 0:19:51We hope that serendipity will play a part tonight.
0:19:56 > 0:20:00We're back at Barbury Castle to look for comet Panstarrs,
0:20:00 > 0:20:03which we hope to see in a couple of hours.
0:20:03 > 0:20:07Pete, Paul and Chris North are here too.
0:20:07 > 0:20:11The sky is fairly clear and we're hopeful.
0:20:11 > 0:20:14But this comet is low down and very faint.
0:20:14 > 0:20:16We're joined by the Wiltshire Astronomical Society
0:20:16 > 0:20:18to look for it and last night,
0:20:18 > 0:20:20member Pete Glastonbury saw the comet
0:20:20 > 0:20:23and what a bonny comet it is too!
0:20:23 > 0:20:25Let's hope we'll be as lucky tonight.
0:20:29 > 0:20:32We're waiting for the darkness to fall
0:20:32 > 0:20:35and when we first arrived, it was awful, wasn't it?
0:20:35 > 0:20:39- It was and it has cleared, I have to say.- It has.- Extremely lucky.
0:20:39 > 0:20:41This is rare on a Sky At Night shoot!
0:20:41 > 0:20:45We are also joined by some of our beginner astronomers...
0:20:45 > 0:20:48Peta and Steve Bosley and Christina Chester.
0:20:48 > 0:20:52They've come to pick up some tips about observing Saturn,
0:20:52 > 0:20:55which is in our April night sky...
0:20:55 > 0:20:58Rising around 10pm at the beginning of the month
0:20:58 > 0:21:01and getting earlier as the month goes on.
0:21:01 > 0:21:04- Have you ever seen Saturn through your telescope?- No, just Jupiter.
0:21:04 > 0:21:08Well, you are in for a real treat with Saturn because it's a stunner.
0:21:08 > 0:21:11That's the planet which actually hooked me into astronomy.
0:21:11 > 0:21:16- How do you find Saturn?- OK, well, you know what The Plough looks like?
0:21:16 > 0:21:19- Yep.- You know the handle of The Plough?
0:21:19 > 0:21:23If you follow the curve of that away from the blade bit,
0:21:23 > 0:21:26if you like, or if you carry on the curve round,
0:21:26 > 0:21:27it comes to Spica -
0:21:27 > 0:21:29the brightest star in Virgo,
0:21:29 > 0:21:30and Saturn is off
0:21:30 > 0:21:32to the lower left of Spica
0:21:32 > 0:21:33and it's about the same brightness.
0:21:34 > 0:21:37- D'you reckon we're going to see the comet tonight?- Fingers crossed.
0:21:37 > 0:21:41I can't see your fingers crossed in those gloves, but I'll trust you.
0:21:42 > 0:21:46So, the reason why Saturn is so good to look at in April
0:21:46 > 0:21:49is because it's at opposition and when a planet is at opposition,
0:21:49 > 0:21:51then this is the best time to look at it.
0:21:51 > 0:21:56We thought we'd do a little demonstration to demonstrate the opposition.
0:21:56 > 0:21:59You are going to be the sun. Peta, you'll be the sun.
0:21:59 > 0:22:02Steve, you can be the Earth. Can I ask you to stand here, please?
0:22:02 > 0:22:06- Of course.- There we are, you are the planet Earth.
0:22:06 > 0:22:12I shall represent Saturn, a ringless Saturn. So this is opposition.
0:22:12 > 0:22:15It is when the sun and the planet in question
0:22:15 > 0:22:17are at opposite sides of the Earth.
0:22:17 > 0:22:20We have the sun in one part of the sky
0:22:20 > 0:22:23and in the opposite direction of the sky we have the planet Saturn.
0:22:25 > 0:22:27How many moons does Saturn...?
0:22:27 > 0:22:28It's got loads of moons,
0:22:28 > 0:22:32but most of them are too faint to be seen with a small telescope.
0:22:32 > 0:22:36But there is a good family of them that go around the planet itself.
0:22:36 > 0:22:38More than you would see with Jupiter.
0:22:38 > 0:22:40They are always in attendance
0:22:40 > 0:22:41and they are really worth
0:22:41 > 0:22:43looking out for as well.
0:22:48 > 0:22:52JON: The darkness and the cold is enveloping us
0:22:52 > 0:22:56but this Iron Age fort feels really quite magical.
0:22:58 > 0:23:02OK, we've got Neil and Hillary here and you're locals?
0:23:02 > 0:23:05- Yes, we're from Devizes.- Have you had any luck finding the comet?
0:23:05 > 0:23:08No, so we're hopeful that we'll see it tonight.
0:23:08 > 0:23:11I think we're all hopeful. Kids, what do you guys get out of it?
0:23:11 > 0:23:15- I like planets and space stations and stuff!- Planets are good.
0:23:15 > 0:23:18I like seeing all the galaxies and the stars and things.
0:23:20 > 0:23:25I think the comet is currently hiding in a bank of cloud
0:23:25 > 0:23:28and comets are really delicate things in the night sky
0:23:28 > 0:23:30so when you get any haze, particularly in a bright sky
0:23:30 > 0:23:33like we've got now, it just washes them out completely.
0:23:33 > 0:23:36It's like a comet filter!
0:23:36 > 0:23:40JON: While we wait in hope for the stubborn clouds to
0:23:40 > 0:23:45clear from the horizon, it is time for our Space Surgery.
0:23:45 > 0:23:48Now, the first in a new feature on the Sky At Night.
0:23:48 > 0:23:52It is our Space Surgery, where we shall do our very best to
0:23:52 > 0:23:55answer the astronomical questions that you may have.
0:23:55 > 0:24:00Our first question comes from Mary Pont of Cambridgeshire
0:24:00 > 0:24:03and she lives in a bungalow, quite low down.
0:24:03 > 0:24:06She's not got a telescope, just her own eyes
0:24:06 > 0:24:11and a pair of 750 binoculars. So is there anything that she can look for?
0:24:11 > 0:24:14The best thing to do, Mary, is to find your way around the rest
0:24:14 > 0:24:17of the sky, so get yourself a night sky guide, perhaps.
0:24:17 > 0:24:19Mary's binoculars aren't too dissimilar to the ones
0:24:19 > 0:24:20I am holding here.
0:24:20 > 0:24:23They're great for hunting for star clusters
0:24:23 > 0:24:25and there are a few examples of that.
0:24:25 > 0:24:27One of the ones with a chart on our website is the M44,
0:24:27 > 0:24:29the Beehive Cluster or Praesepe.
0:24:29 > 0:24:31It's a really great place to start,
0:24:31 > 0:24:35and looks fabulous in a pair of binoculars like these.
0:24:35 > 0:24:37This next question is a great one and I used to wonder this
0:24:37 > 0:24:39when I was a lad.
0:24:39 > 0:24:42Why are planets, stars and moons perfectly round
0:24:42 > 0:24:44and are there any that are not?
0:24:44 > 0:24:47So asks Lawrence from Eccles.
0:24:47 > 0:24:49It's a very good question
0:24:49 > 0:24:52and the answer quite simply is gravity, so once a rocky object
0:24:52 > 0:24:55which is what planets, moons and asteroids are made of,
0:24:55 > 0:24:59gets more than a few hundred kilometres across in diameter,
0:24:59 > 0:25:02then its own self gravity, its own gravitational pull,
0:25:02 > 0:25:06its own mass, pulls everything into pretty much a round sphere.
0:25:06 > 0:25:08A great example is some of Saturn's moons,
0:25:08 > 0:25:11the bigger moons such as Rhea, Titan and Enceladus
0:25:11 > 0:25:15are nice, round bodies but some of the smaller ones such as Prometheus
0:25:15 > 0:25:17and Pandora are much more odd shapes
0:25:17 > 0:25:21because they're too small for gravity to have pulled them.
0:25:22 > 0:25:26The next question is from another Chris, Chris Fordham in Huddersfield.
0:25:26 > 0:25:30As our galaxy is so vast, is there a simple way to tell
0:25:30 > 0:25:35when looking at stars if they are outside our Milky Way?
0:25:35 > 0:25:38The simple answer is that all the stars you can see
0:25:38 > 0:25:39are our inside our own galaxy.
0:25:39 > 0:25:43Measuring distance to objects in astronomy has always been a challenge.
0:25:43 > 0:25:46There are various ways of doing it and there was a result out
0:25:46 > 0:25:49that we've just measured the distance to one of the nearest galaxies,
0:25:49 > 0:25:53the Large Magellanic Cloud through knowing the properties
0:25:53 > 0:25:55of those stars in the galaxy themselves
0:25:55 > 0:25:57and by determining those, we've measured the distance to that
0:25:57 > 0:26:03of 163,000 light years to within an accuracy of one part in 50.
0:26:03 > 0:26:07So we are getting much better at measuring distances to stars in other galaxies,
0:26:07 > 0:26:11but it is actually something that in astronomy is very hard to do.
0:26:11 > 0:26:14If you have a question, we'll do our best to answer it,
0:26:14 > 0:26:16so send it to us at...
0:26:24 > 0:26:26Well, we didn't actually get to see the comet in the end,
0:26:26 > 0:26:28- did we, chaps?- No, we didn't. - But not to worry.
0:26:28 > 0:26:30We have a beautiful, clear night here.
0:26:30 > 0:26:32It's not the last chance to find it, right?
0:26:32 > 0:26:35No. Comet C2011 L4 Panstarrs
0:26:35 > 0:26:39will be in our skies for some time yet.
0:26:39 > 0:26:42It's getting fainter as time goes on,
0:26:42 > 0:26:44but throughout the month of April,
0:26:44 > 0:26:49it'll pass up through Andromeda, through Cassiopeia toward Cepheus.
0:26:49 > 0:26:53And it actually goes quite close to the Andromeda galaxy as well.
0:26:53 > 0:26:56A good opportunity to pick out the comet still throughout
0:26:56 > 0:26:58the month of April.
0:26:58 > 0:27:00Sadly it eluded us.
0:27:00 > 0:27:05That bank of cloud was like two pub bouncers saying you're not coming in!
0:27:08 > 0:27:12We may have been unlucky, but not so for many of you.
0:27:12 > 0:27:15Our Flickr site has some amazing images of the comets
0:27:15 > 0:27:17from around the world.
0:27:17 > 0:27:23You can see the best of them on our website at bbc.co.uk/skyatnight.
0:27:37 > 0:27:40We have one more celestial treat.
0:27:40 > 0:27:42Lucy and Chris have been allowed
0:27:42 > 0:27:44to hold something rather precious.
0:27:47 > 0:27:50Well, this is something really special.
0:27:50 > 0:27:53This is a piece of Martian meteorite and so this little rock
0:27:53 > 0:27:57knew Mars when it was a wet world, travelled out into space
0:27:57 > 0:28:01and then ended up here on Earth, where it can tell us its story.
0:28:01 > 0:28:03I'm holding the piece of the moon that Anton showed me earlier on.
0:28:03 > 0:28:07Trapped in this tiny fragment is the history of the lunar surface
0:28:07 > 0:28:09from that area.
0:28:09 > 0:28:12A huge thank you to the Natural History Museum for showing us
0:28:12 > 0:28:15behind the scenes and allowing us to hold these very special objects.
0:28:15 > 0:28:19When we come back next month, we'll be going past the moon,
0:28:19 > 0:28:21past Mars and on out to Saturn.
0:28:21 > 0:28:22So, until next month...
0:28:22 > 0:28:24- BOTH:- Good night.
0:28:41 > 0:28:44Subtitles by Red Bee Media Ltd