BOTH: Hello. Welcome to the Natural History Museum
here in London.
This is the Otumpa meteorite, a piece of space that fell to Earth.
When I first came here as a small boy I ran through the gallery to try
and get close to it. I am still impressed today.
This programme is all about meteorites.
We've come to see the museum's fantastic collection of space rocks
and find out what we're still learning about them today.
Jon Culshaw has been on a meteorite hunt of his own in Wiltshire.
And Chris North has something new, our first Space Surgery.
Seeing any fireball falling to Earth is very special.
ALL: Wow!
What a corker!
Meteorites are essentially space rocks that are unlucky enough
to collide with Earth.
Last month, asteroid 2012 DA14 had a lucky escape, swinging past
close enough for Sky At Night viewers to capture these amazing images.
Most meteorites are small
and the product of a collision between asteroids
resulting in millions of tiny, rocky fragments which float in space.
Some get in our way and then burn up in the Earth's atmosphere,
sometimes creating a fireball and sometimes landing on Earth.
ALL: Oh!
But meteorites can come from all sorts of places,
sometimes from comets and sometimes even from other planets.
Meteorites are our best way of
getting hold of a piece of another world and looking at it close up.
The Natural History Museum has one of the finest collections
anywhere in the world.
This is just fabulous.
This is an enormous piece of Mars that fell to Earth in 2011.
That impact was observed and this is a fresh Martian meteorite,
kept in this case to keep it away from Earthly contamination.
That means it can tell us stories of the Red Planet
and this particular rock is the only Martian meteorite to show
signs of water, weathering it away in the dim and distant past on Mars.
These are the latest images from our rovers on Mars
and their self-portraits show them hard at work
on the surface of the Red Planet.
Even though they're doing amazing science, nothing beats getting
hold of a lump of Mars and bringing it down into the lab.
700,000 years ago, an impact on Mars resulted in debris
being flung into space.
What became the Tissint meteorite
down to Earth, providing us with a hands-on guide to Mars' past.
At the Natural History Museum, they're using medical CT scanning
technology to build up an image of Tissint and its insides.
They're looking for holes or voids inside the rock
which could be filled with Martian air.
This is a CT scan of a small fragment of Tissint
that I looked at last year in the summer.
'Caroline Smith is the meteorite curator.'
Just to give you an idea,
it is about the size of the end of my little finger.
Quite a small thing.
What we're seeing here is a video, a movie
as if we're sort of flying through the specimen.
'The CT scan has revealed a hole in Tissint which is filled with air.'
The question is, if this has got air in it,
is it Earth air or Martian air?
If it is completely sealed in the rock,
theoretically it still should have Martian air in it.
That's what we wanted to find out.
You can see it is completely sealed at this end.
Oh, but hang on, we've got all of this red stuff here
and in fact there is a little hole. Oh no!
Yeah, so if there was any Martian atmosphere in there,
it ain't there now!
We wouldn't have been able to do this a few years ago.
With this, we can get a really good
idea of what's inside the meteorite without having to chop it up,
without having to cut it, without having to break it.
Whenever you do those to any samples, but especially
rare meteorites of course,
you're damaging something rare and precious.
Meteorites are classified by their composition.
Some are made of stone, but some are made of iron,
the condensed cores of what must have been larger asteroids.
Some are mixtures of both.
The most interesting meteorites are relics of a time nearly
five billion years ago, when our solar system was just forming.
Out of the dust and debris left over from the birth of our sun,
planets were eventually formed.
But the details are sketchy and what we need is first-hand evidence.
We get just that in the form of meteorites
called carbonaceous chondrites,
the fossilised remains of the primeval solar system.
So, we're in the carbonaceous chondrite drawer.
You can see there's lots of different labels.
What do they look like? How would we know one if it landed in the back garden?
They're actually quite boring-looking rocks, actually.
But that's the thing.
Their lack of looking interesting belies their significance
because they're actually some of the most interesting
meteorites that we actually have to study. This is called Allende.
Why Allende is very important is primarily because of these things.
You can see on the surface of this one is this white splodge.
And then you can see inside as well, there's lots of
sort of smaller, irregularly shaped white objects.
These are these things called CAIs,
stands for calcium aluminium-rich inclusion.
And the CAIs, we think, are the first solid objects to form
in our solar system.
When we talk about the solar system being 4.6 billion years,
it is actually dating the CAIs
and in fact, we think in the very, very early solar system,
in this protoplanetary disc, that's where these rocks
were beginning to form by bits and pieces all sticking together.
Another reason why carbonaceous chondrites are particularly
interesting is because some of them are very rich in organic molecules.
Right, there is a story about this, isn't there? Is it the Murchison one?
That's right, the Murchison is one of my favourite meteorites.
That means it's smelly. That's what I have heard anyway.
Murchison is smelly.
Oh, yeah, you get a really strong gunpowder smell out of it.
It's quite amazing, so I will try...
And that's been given off by the meteorite?
This has been given off by the meteorite.
Now, I will sort of take it out, hopefully no bits will drop off!
It's quite fragile. So this is a fairly large piece.
This one weighs about 800 grams.
You can hold it but very carefully, because it is quite friable.
And you can see again, a bit like Allende,
quite a boring-looking meteorite, but it is very, very,
very rich in organic molecules - amino acids,
sugars and perhaps the most interesting, I think,
are nuclear bases, because nuclear bases are the organic molecules
you need for DNA to replicate.
I was going to say, these are complicated molecules.
These are complicated molecules.
Asteroids and comets carry in them the building blocks of life,
which then fall to Earth in meteorites.
More than 1,000 meteorites fall to Earth every year.
Caroline regularly goes meteorite hunting in the desert,
where conditions are ideal for preserving them.
In 2010 in Australia, she found a funny little rock,
which at first glance, looked nothing special.
Lucy is meeting up with Anton Kearsley
in the basement of the museum.
He used his electron microscope to look at Caroline's find
and was amazed at what he found.
It was something incredibly rare - a meteorite from the moon.
This is an image of a cutaway of the meteorite,
magnified by a certain number of times. That's right.
On the screen at the moment, it is about 300 times magnification.
On the picture over here, you can
see that the whole thing is just over a centimetre in size.
It's about a fingernail size.
And this is a really curious little area.
Because there's a little dark grey patch
with some little pale grey patches inside it.
And when you start analysing the pale grey patches,
these ones turn out to have a very interesting chemical composition.
It turns out to be quite unlike the composition of things
that we find on Earth. OK.
This is a little mineral again, silicate mineral
but now it's got a lot of very strange elements in it.
It's got zirconium, and yttrium
and titanium and iron and silicon,
it's actually quite well-known,
but it's called tranquillityite.
The Mare Tranquillitatis -
one of the most famous features on the moon
and where man first stood.
These precious meteorites give us
clues about the moon's ancient past and how it's changed,
which is why finding them in pristine condition is so important.
This is the largest meteorite in the museum's collection from Cranborne
in Australia and at three-and-a-half tons,
it weighs the same as four cars.
It's an impressive beast and it is older than the Earth.
But, we have some impressive meteorites in Britain too
and Jon has been on the trail of one of them.
This one may have been carried along by a glazier and it even
attracted the interest of prehistoric man,
but it was rediscovered sitting on someone's doorstep.
This is the Iron Age hill fort at Barbury Castle near Swindon,
first occupied some 2,500 years ago.
And what a wonderfully atmospheric and peaceful place this is.
There's a real air of mystery around here.
And all around you can see the remnants of the influence
of ancient man - this Iron Age fort, burial mounds, and it brings to mind
those stories of those Victorian amateur archaeologists who used
to love to explore and dig things up and whatever they found fascinating
or just liked the look of, they would take home to their collections.
This old photograph from Country Life in 1908 is of the Lake House mansion
in Wiltshire, once owned by the Rev Edward Duke.
He was known to excavate local burial grounds,
keeping any interesting pieces for his own private collection.
On the doorstep is certainly something very interesting.
It's the Lake House meteorite.
Here at the Salisbury and South Wiltshire Museum,
I met up with Professor Colin Pillinger.
'He's become a meteorite detective and he's been piecing together
'the history of the Lake House meteorite.'
Ah! There it is. The Lake House meteorite. Indeed. You can't miss it.
It's a fair size, isn't it? Well,
it is 92.5 kilograms. Wow!
But this is not only the biggest British meteorite that we
know about, it is also the one that has been longest on Earth
and it was when we made that measurement that all of us
suddenly realised we had something quite exciting.
So how old exactly is this meteorite
and how long has it been on the Earth?
It's technically 4.5, 4.6 billion years old.
It's been on Earth 32,000 years
but to try and explain how it survived 32,000 years,
you have to tease some facts out of it.
32,000 years ago on Salisbury Plain,
the place was covered in ice.
We're confident that we know meteorites survive very well in ice,
because we collect lots of meteorites on Antarctica.
How do you explain the next bit?
Bronze Age people living on Salisbury Plain,
sort of 4,000 years ago
were building mounds to bury their important people.
The meteorite was then put into one of these barrows.
The majority of the rock that they used would have been chalk.
You've these lovely pictures of the meteorite on the step, you see
the patches of chalk still on the meteorite,
so it clearly was packed somewhere closely associated with chalk.
So the story goes, 32,000 years ago a meteorite fell in Britain
and was preserved in a glacier,
then used by Bronze Age man to build his burial mound
and dug up by a Victorian archaeologist.
Using a series of clues, Colin has revealed an extraordinary tale
about an extraordinary meteorite.
A wonderful piece of serendipity.
The needle left the haystack and made its way to you. Absolutely.
Science is a lot of serendipity.
Such good fun.
We hope that serendipity will play a part tonight.
We're back at Barbury Castle to look for comet Panstarrs,
which we hope to see in a couple of hours.
Pete, Paul and Chris North are here too.
The sky is fairly clear and we're hopeful.
But this comet is low down and very faint.
We're joined by the Wiltshire Astronomical Society
to look for it and last night,
member Pete Glastonbury saw the comet
and what a bonny comet it is too!
Let's hope we'll be as lucky tonight.
We're waiting for the darkness to fall
and when we first arrived, it was awful, wasn't it?
It was and it has cleared, I have to say. It has. Extremely lucky.
This is rare on a Sky At Night shoot!
JON: The darkness and the cold is enveloping us
but this Iron Age fort feels really quite magical.
OK, we've got Neil and Hillary here and you're locals?
Yes, we're from Devizes. Have you had any luck finding the comet?
No, so we're hopeful that we'll see it tonight.
I think we're all hopeful. Kids, what do you guys get out of it?
I like planets and space stations and stuff! Planets are good.
I like seeing all the galaxies and the stars and things.
I think the comet is currently hiding in a bank of cloud
and comets are really delicate things in the night sky
so when you get any haze, particularly in a bright sky
like we've got now, it just washes them out completely.
It's like a comet filter!
JON: While we wait in hope for the stubborn clouds to
clear from the horizon, it is time for our Space Surgery.
Now, the first in a new feature on the Sky At Night.
It is our Space Surgery, where we shall do our very best to
answer the astronomical questions that you may have.
Our first question comes from Mary Pont of Cambridgeshire
and she lives in a bungalow, quite low down.
She's not got a telescope, just her own eyes
and a pair of 750 binoculars. So is there anything that she can look for?
The best thing to do, Mary, is to find your way around the rest
of the sky, so get yourself a night sky guide, perhaps.
Mary's binoculars aren't too dissimilar to the ones
I am holding here.
They're great for hunting for star clusters
and there are a few examples of that.
One of the ones with a chart on our website is the M44,
the Beehive Cluster or Praesepe.
It's a really great place to start,
and looks fabulous in a pair of binoculars like these.
This next question is a great one and I used to wonder this
when I was a lad.
Why are planets, stars and moons perfectly round
and are there any that are not?
So asks Lawrence from Eccles.
It's a very good question
and the answer quite simply is gravity, so once a rocky object
which is what planets, moons and asteroids are made of,
gets more than a few hundred kilometres across in diameter,
then its own self gravity, its own gravitational pull,
its own mass, pulls everything into pretty much a round sphere.
A great example is some of Saturn's moons,
the bigger moons such as Rhea, Titan and Enceladus
are nice, round bodies but some of the smaller ones such as Prometheus
and Pandora are much more odd shapes
because they're too small for gravity to have pulled them.
If you have a question, we'll do our best to answer it,
so send it to us at...
Well, we didn't actually get to see the comet in the end,
did we, chaps? No, we didn't. But not to worry.
We have a beautiful, clear night here.
It's not the last chance to find it, right?
No. Comet C2011 L4 Panstarrs
will be in our skies for some time yet.
It's getting fainter as time goes on,
but throughout the month of April,
it'll pass up through Andromeda, through Cassiopeia toward Cepheus.
And it actually goes quite close to the Andromeda galaxy as well.
A good opportunity to pick out the comet still throughout
the month of April.
Sadly it eluded us.
That bank of cloud was like two pub bouncers saying you're not coming in!
We may have been unlucky, but not so for many of you.
Our Flickr site has some amazing images of the comets
from around the world.
You can see the best of them on our website at bbc.co.uk/skyatnight.
We have one more celestial treat.
Lucy and Chris have been allowed
to hold something rather precious.
Well, this is something really special.
This is a piece of Martian meteorite and so this little rock
knew Mars when it was a wet world, travelled out into space
and then ended up here on Earth, where it can tell us its story.
I'm holding the piece of the moon that Anton showed me earlier on.
Trapped in this tiny fragment is the history of the lunar surface
from that area.
A huge thank you to the Natural History Museum for showing us
behind the scenes and allowing us to hold these very special objects.
When we come back next month, we'll be going past the moon,
past Mars and on out to Saturn.
So, until next month...
BOTH: Good night.
Subtitles by Red Bee Media Ltd