Browse content similar to They Fall to Earth. Check below for episodes and series from the same categories and more!
Line | From | To | |
---|---|---|---|
-BOTH: Hello. -Welcome to the Natural History Museum | 0:00:34 | 0:00:37 | |
here in London. | 0:00:37 | 0:00:38 | |
This is the Otumpa meteorite, a piece of space that fell to Earth. | 0:00:38 | 0:00:42 | |
When I first came here as a small boy I ran through the gallery to try | 0:00:42 | 0:00:45 | |
and get close to it. I am still impressed today. | 0:00:45 | 0:00:48 | |
This programme is all about meteorites. | 0:00:48 | 0:00:50 | |
We've come to see the museum's fantastic collection of space rocks | 0:00:50 | 0:00:53 | |
and find out what we're still learning about them today. | 0:00:53 | 0:00:56 | |
We'll bring you the latest on the Chelyabinsk impact in Russia, | 0:00:56 | 0:01:00 | |
and Jon Culshaw has been on a meteorite hunt of his own in Wiltshire. | 0:01:00 | 0:01:04 | |
Pete and Paul have tips on what to see in this month's night sky, | 0:01:04 | 0:01:07 | |
and Chris North has something new - our first Space Surgery. | 0:01:07 | 0:01:11 | |
Seeing any fireball falling to Earth is very special. | 0:01:13 | 0:01:17 | |
ALL: Wow! | 0:01:17 | 0:01:20 | |
What a corker! | 0:01:20 | 0:01:22 | |
Meteorites are essentially space rocks that are unlucky enough | 0:01:22 | 0:01:26 | |
to collide with Earth. | 0:01:26 | 0:01:27 | |
Last month, asteroid 2012 DA14 had a lucky escape, swinging past | 0:01:27 | 0:01:33 | |
close enough for Sky At Night viewers to capture these amazing images. | 0:01:33 | 0:01:37 | |
Most meteorites are small | 0:01:42 | 0:01:43 | |
and the product of a collision between asteroids | 0:01:43 | 0:01:46 | |
resulting in millions of tiny, rocky fragments which float in space. | 0:01:46 | 0:01:51 | |
Some get in our way and then burn up in the Earth's atmosphere, | 0:01:51 | 0:01:55 | |
sometimes creating a fireball and sometimes landing on Earth. | 0:01:55 | 0:01:58 | |
ALL: Oh! | 0:02:02 | 0:02:03 | |
But meteorites can come from all sorts of places, | 0:02:03 | 0:02:06 | |
sometimes from comets and sometimes even from other planets. | 0:02:06 | 0:02:10 | |
Meteorites are our best way of getting ahold | 0:02:13 | 0:02:15 | |
of a piece of another world and looking at it close-up. | 0:02:15 | 0:02:19 | |
The Natural History Museum has one of the finest collections | 0:02:21 | 0:02:24 | |
anywhere in the world. | 0:02:24 | 0:02:26 | |
This is just fabulous. | 0:02:26 | 0:02:28 | |
This is an enormous piece of Mars that fell to Earth in 2011. | 0:02:28 | 0:02:33 | |
That impact was observed and this is a fresh Martian meteorite, | 0:02:33 | 0:02:36 | |
kept in this case to keep it away from Earthly contamination. | 0:02:36 | 0:02:40 | |
That means it can tell us stories of the Red Planet | 0:02:40 | 0:02:44 | |
and this particular rock is the only Martian meteorite to show | 0:02:44 | 0:02:47 | |
signs of water, weathering it away in the dim and distant past on Mars. | 0:02:47 | 0:02:52 | |
These are the latest images from our rovers on Mars | 0:02:57 | 0:03:01 | |
and their self-portraits show them hard at work | 0:03:01 | 0:03:03 | |
on the surface of the Red Planet. | 0:03:03 | 0:03:05 | |
Even though they're doing amazing science, nothing beats getting | 0:03:05 | 0:03:09 | |
hold of a lump of Mars and bringing it down into the lab. | 0:03:09 | 0:03:12 | |
700,000 years ago, an impact on Mars resulted in debris | 0:03:14 | 0:03:18 | |
being flung into space. | 0:03:18 | 0:03:20 | |
What became the Tissint meteorite wandered through space before falling | 0:03:24 | 0:03:28 | |
down to Earth, providing us with a hands-on guide to Mars' past. | 0:03:28 | 0:03:33 | |
At the Natural History Museum, they're using medical CT scanning | 0:03:35 | 0:03:39 | |
technology to build up an image of Tissint and its insides. | 0:03:39 | 0:03:44 | |
They're looking for holes or voids inside the rock | 0:03:44 | 0:03:47 | |
which could be filled with Martian air. | 0:03:47 | 0:03:50 | |
This is a CT scan of a small fragment of Tissint | 0:03:54 | 0:03:58 | |
that I looked at last year in the summer. | 0:03:58 | 0:04:01 | |
'Caroline Smith is the meteorite curator.' | 0:04:01 | 0:04:04 | |
Just to give you an idea, | 0:04:04 | 0:04:05 | |
it is about the size of the end of my little finger. | 0:04:05 | 0:04:08 | |
Quite a small thing. | 0:04:08 | 0:04:09 | |
What we're seeing here is a video, a movie | 0:04:09 | 0:04:12 | |
as if we're sort of flying through the specimen. | 0:04:12 | 0:04:14 | |
'The CT scan has revealed a hole in Tissint which is filled with air.' | 0:04:14 | 0:04:19 | |
The question is, if this has got air in it, | 0:04:19 | 0:04:22 | |
is it Earth air or Martian air? | 0:04:22 | 0:04:24 | |
If it is completely sealed in the rock, | 0:04:24 | 0:04:27 | |
theoretically it still should have Martian air in it. | 0:04:27 | 0:04:30 | |
That's what we wanted to find out. | 0:04:30 | 0:04:32 | |
You can see it is completely sealed at this end. | 0:04:32 | 0:04:35 | |
Oh, but hang on, we've got all of this red stuff here | 0:04:35 | 0:04:38 | |
-and in fact, there is a little hole. -Oh, no! | 0:04:38 | 0:04:40 | |
Yeah, so if there was any Martian atmosphere in there, | 0:04:40 | 0:04:43 | |
it ain't there now! | 0:04:43 | 0:04:45 | |
We wouldn't have been able to do this a few years ago. | 0:04:45 | 0:04:47 | |
With this, we can get a really good | 0:04:47 | 0:04:49 | |
idea of what's inside the meteorite without having to chop it up, | 0:04:49 | 0:04:53 | |
without having to cut it, without having to break it. | 0:04:53 | 0:04:55 | |
Whenever you do those to any samples, but especially | 0:04:55 | 0:04:58 | |
rare meteorites, of course, | 0:04:58 | 0:04:59 | |
you're damaging something rare and precious. | 0:04:59 | 0:05:01 | |
Meteorites are classified by their composition. | 0:05:03 | 0:05:06 | |
Some are made of stone, but some are made of iron, | 0:05:06 | 0:05:09 | |
the condensed cores of what must have been larger asteroids. | 0:05:09 | 0:05:13 | |
Some are mixtures of both. | 0:05:13 | 0:05:15 | |
The most interesting meteorites are relics of a time nearly | 0:05:17 | 0:05:20 | |
five billion years ago, when our solar system was just forming. | 0:05:20 | 0:05:25 | |
Out of the dust and debris left over from the birth of our sun, | 0:05:25 | 0:05:29 | |
planets were eventually formed. | 0:05:29 | 0:05:31 | |
But the details are sketchy and what we need is first-hand evidence. | 0:05:31 | 0:05:36 | |
We get just that in the form of meteorites | 0:05:36 | 0:05:38 | |
called carbonaceous chondrites, | 0:05:38 | 0:05:41 | |
the fossilised remains of the primeval solar system. | 0:05:41 | 0:05:45 | |
So, we're in the carbonaceous chondrite drawer. | 0:05:48 | 0:05:51 | |
You can see there's lots of different labels. | 0:05:51 | 0:05:53 | |
What do they look like? How would we know one if it landed in the back garden? | 0:05:53 | 0:05:57 | |
They're actually quite boring-looking rocks, actually. | 0:05:57 | 0:06:00 | |
But that's the thing. | 0:06:00 | 0:06:01 | |
Their lack of looking interesting belies their significance | 0:06:01 | 0:06:05 | |
because they're actually some of the most interesting | 0:06:05 | 0:06:08 | |
meteorites that we actually have to study. This is called Allende. | 0:06:08 | 0:06:11 | |
Why Allende is very important is primarily because of these things. | 0:06:11 | 0:06:16 | |
You can see on the surface of this one is this white splodge. | 0:06:16 | 0:06:20 | |
And then you can see inside as well, there's lots of sort of smaller, | 0:06:20 | 0:06:24 | |
irregularly shaped white objects. | 0:06:24 | 0:06:26 | |
These are these things called CAIs, | 0:06:26 | 0:06:29 | |
stands for calcium aluminium-rich inclusion. | 0:06:29 | 0:06:32 | |
And the CAIs, we think, are the first solid objects to form | 0:06:32 | 0:06:36 | |
in our solar system. | 0:06:36 | 0:06:37 | |
When we talk about the solar system being 4.6 billion years, | 0:06:37 | 0:06:42 | |
it's actually dating the CAIs | 0:06:42 | 0:06:44 | |
and in fact, we think in the very, very early solar system, | 0:06:44 | 0:06:48 | |
in this protoplanetary disc, that's where these rocks | 0:06:48 | 0:06:51 | |
were beginning to form by bits and pieces all sticking together. | 0:06:51 | 0:06:54 | |
Another reason why carbonaceous chondrites are particularly | 0:06:56 | 0:06:59 | |
interesting is because some of them are very rich in organic molecules. | 0:06:59 | 0:07:03 | |
Right, there is a story about this, isn't there? Is it the Murchison one? | 0:07:03 | 0:07:06 | |
That's right, the Murchison is one of my favourite meteorites. | 0:07:06 | 0:07:10 | |
That means it's smelly. That's what I have heard anyway. | 0:07:10 | 0:07:13 | |
Murchison is smelly. | 0:07:13 | 0:07:14 | |
Oh, yeah, you get a really strong gunpowder smell out of it. | 0:07:16 | 0:07:19 | |
It's quite amazing, so I will try... | 0:07:19 | 0:07:21 | |
And that's been given off by the meteorite? | 0:07:21 | 0:07:24 | |
This has been given off by the meteorite. | 0:07:24 | 0:07:26 | |
Now, I will sort of take it out, hopefully no bits will drop off! | 0:07:26 | 0:07:29 | |
It's quite fragile. So this is a fairly large piece. | 0:07:29 | 0:07:32 | |
This one weighs about 800 grams. | 0:07:32 | 0:07:35 | |
You can hold it but very carefully, because it is quite friable. | 0:07:35 | 0:07:39 | |
And you can see again, a bit like Allende, | 0:07:39 | 0:07:41 | |
quite a boring-looking meteorite, but it is very, very, | 0:07:41 | 0:07:44 | |
very rich in organic molecules - amino acids, | 0:07:44 | 0:07:47 | |
sugars and perhaps the most interesting, I think, | 0:07:47 | 0:07:51 | |
are nuclear bases, because nuclear bases are the organic molecules | 0:07:51 | 0:07:55 | |
you need for DNA to replicate. | 0:07:55 | 0:07:57 | |
I was going to say, these are complicated molecules. | 0:07:57 | 0:07:59 | |
These are complicated molecules. | 0:07:59 | 0:08:01 | |
Asteroids and comets carry in them the building blocks of life, | 0:08:02 | 0:08:06 | |
which then fall to Earth in meteorites. | 0:08:06 | 0:08:08 | |
They have a sinister presence, emerging from the blackness | 0:08:10 | 0:08:14 | |
and then disappearing silently again. | 0:08:14 | 0:08:17 | |
They're dark, cratered worlds, scarred by impacts - | 0:08:17 | 0:08:20 | |
most ancient, but some quite recent. | 0:08:20 | 0:08:23 | |
Tracked by telescopes, | 0:08:25 | 0:08:27 | |
we know precisely where the large ones are, | 0:08:27 | 0:08:29 | |
but the vast majority of asteroids are too small for us to detect | 0:08:29 | 0:08:33 | |
until the last minute. | 0:08:33 | 0:08:34 | |
A fireball is the only sign that something's on the way. | 0:08:37 | 0:08:41 | |
The last meteorite to fall in the UK was in 1991. | 0:08:43 | 0:08:47 | |
In that typically understated British way, | 0:08:47 | 0:08:50 | |
it didn't make much of a fuss | 0:08:50 | 0:08:52 | |
when it landed in Mr Pettifor's garden, near Cambridge. | 0:08:52 | 0:08:54 | |
They heard a whistling noise and the neighbour said, | 0:08:56 | 0:09:00 | |
"Arthur, I think something's just landed in your garden." | 0:09:00 | 0:09:03 | |
Right at the back of the garden they found this dark rock sitting | 0:09:03 | 0:09:08 | |
where there had been no dark rock, | 0:09:08 | 0:09:10 | |
and Mr Pettifor was clever enough to realise that this was | 0:09:10 | 0:09:13 | |
something quite unusual and maybe this was a meteorite. | 0:09:13 | 0:09:16 | |
You get lots of these calls | 0:09:16 | 0:09:18 | |
from people who think they've found meteorites. | 0:09:18 | 0:09:20 | |
A few hundred a year, yes! | 0:09:20 | 0:09:22 | |
So when you go out to chase one of these up - | 0:09:22 | 0:09:25 | |
the story sounds convincing - but what do you look for in the rock? | 0:09:25 | 0:09:28 | |
The first thing that's very characteristic | 0:09:28 | 0:09:30 | |
is the very, very dark crust. | 0:09:30 | 0:09:32 | |
-Burnt is the wrong word... -Well, it's melted rock. | 0:09:32 | 0:09:36 | |
It's called the fusion crust, so as this meteorite was hurtling through | 0:09:36 | 0:09:40 | |
Earth's atmosphere, | 0:09:40 | 0:09:41 | |
the rock actually melts, but only on the outside. | 0:09:41 | 0:09:44 | |
The inside never gets hot enough to melt. | 0:09:44 | 0:09:47 | |
I'm going to give away a little secret here. | 0:09:48 | 0:09:51 | |
One of the ways that we filter calls when people say, | 0:09:51 | 0:09:54 | |
"A meteorite landed in my garden last night," | 0:09:54 | 0:09:56 | |
we always say to them, "What happened? Was it hot when you picked it up?" | 0:09:56 | 0:09:59 | |
As soon as they say, "Yes, it was boiling hot," | 0:09:59 | 0:10:02 | |
or, "It set the grass on fire," or whatever, | 0:10:02 | 0:10:04 | |
then it's not a meteorite | 0:10:04 | 0:10:06 | |
because the very few occasions, I should say, | 0:10:06 | 0:10:08 | |
where meteorites have landed and somebody has picked them up | 0:10:08 | 0:10:12 | |
almost immediately afterwards, they are described as being "lukewarm." | 0:10:12 | 0:10:16 | |
Well, this is the last British meteorite, | 0:10:18 | 0:10:20 | |
but of course, we've had the Russian meteorite in Chelyabinsk, which was very exciting. | 0:10:20 | 0:10:24 | |
What do we know about that? | 0:10:24 | 0:10:25 | |
The best guesstimate at the moment for the size of the object | 0:10:25 | 0:10:28 | |
when it came into the Earth's atmosphere | 0:10:28 | 0:10:31 | |
is about 17 metres wide. | 0:10:31 | 0:10:33 | |
What sort of percentage survives to the ground? | 0:10:33 | 0:10:35 | |
Well, it's difficult to say, | 0:10:35 | 0:10:37 | |
but you might lose at least half the pre-atmospheric mass and size... | 0:10:37 | 0:10:42 | |
Thousands of stones have already been recovered | 0:10:42 | 0:10:44 | |
and the largest one, I think, is about two kilograms. | 0:10:44 | 0:10:47 | |
Is there scientific value in getting it so soon after an impact? | 0:10:47 | 0:10:51 | |
Oh, absolutely. | 0:10:51 | 0:10:53 | |
The less time a meteorite is sitting around on the ground for, | 0:10:53 | 0:10:56 | |
the less it is being contaminated. | 0:10:56 | 0:10:58 | |
More than 1,000 meteorites fall to Earth every year. | 0:11:02 | 0:11:05 | |
Caroline regularly goes meteorite hunting in the desert, | 0:11:08 | 0:11:11 | |
where conditions are ideal for preserving them. | 0:11:11 | 0:11:14 | |
In 2010 in Australia, she found a funny little rock, | 0:11:14 | 0:11:19 | |
which at first glance, looked nothing special. | 0:11:19 | 0:11:22 | |
Lucy is meeting up with Anton Kearsley | 0:11:22 | 0:11:25 | |
in the basement of the museum. | 0:11:25 | 0:11:27 | |
He used his electron microscope to look at Caroline's find | 0:11:27 | 0:11:30 | |
and was amazed at what he found. | 0:11:30 | 0:11:33 | |
It was something incredibly rare - a meteorite from the moon. | 0:11:33 | 0:11:39 | |
This is an image of a cutaway of the meteorite, | 0:11:39 | 0:11:43 | |
-magnified by a certain number of times. -That's right. | 0:11:43 | 0:11:46 | |
On the screen at the moment, it is about 300 times magnification. | 0:11:46 | 0:11:48 | |
On the picture over here, | 0:11:48 | 0:11:50 | |
you can see that the whole thing is just over a centimetre in size. | 0:11:50 | 0:11:53 | |
It's about a fingernail size. | 0:11:53 | 0:11:56 | |
And this is a really curious little area. | 0:11:57 | 0:12:00 | |
Because there's a little dark grey patch | 0:12:01 | 0:12:04 | |
with some little pale grey patches inside it. | 0:12:04 | 0:12:08 | |
And when you start analysing the pale grey patches, | 0:12:08 | 0:12:11 | |
these ones turn out to have a very interesting chemical composition. | 0:12:11 | 0:12:15 | |
It turns out to be quite unlike the composition of things | 0:12:15 | 0:12:18 | |
-that we find on Earth. -OK. | 0:12:18 | 0:12:20 | |
This is a little mineral again, silicate mineral | 0:12:21 | 0:12:24 | |
but now it's got a lot of very strange elements in it. | 0:12:24 | 0:12:27 | |
It's got zirconium, and yttrium | 0:12:27 | 0:12:30 | |
and titanium and iron and silicon, | 0:12:30 | 0:12:32 | |
it's actually quite well-known, | 0:12:32 | 0:12:35 | |
but it's called tranquillityite. | 0:12:35 | 0:12:38 | |
The Mare Tranquillitatis - | 0:12:39 | 0:12:42 | |
one of the most famous features on the moon | 0:12:42 | 0:12:44 | |
and where man first stood. | 0:12:44 | 0:12:46 | |
These precious meteorites give us | 0:12:46 | 0:12:49 | |
clues about the moon's ancient past and how it's changed, | 0:12:49 | 0:12:53 | |
which is why finding them in pristine condition is so important. | 0:12:53 | 0:12:58 | |
On Earth, deserts hot and cold | 0:12:58 | 0:13:01 | |
are ideal for preserving these extraterrestrial rocks. | 0:13:01 | 0:13:05 | |
The Antarctic has become the new Mecca for meteorite hunters. | 0:13:05 | 0:13:10 | |
Since 1976, ANSMET, | 0:13:10 | 0:13:13 | |
the US Antarctic Search for Meteorites program | 0:13:13 | 0:13:17 | |
has retrieved 20,000 meteorites. | 0:13:17 | 0:13:21 | |
Lunar scientist Katie Joy spent two months in Antarctica | 0:13:21 | 0:13:25 | |
and her group managed to collect 63 meteorites, | 0:13:25 | 0:13:28 | |
but they were hampered by the wind | 0:13:28 | 0:13:31 | |
and temperatures of -25 degrees centigrade. | 0:13:31 | 0:13:35 | |
Katie returned in January | 0:13:35 | 0:13:36 | |
and to remind her of her Antarctic experiences | 0:13:36 | 0:13:39 | |
we took her to a bar in central London made completely of ice | 0:13:39 | 0:13:44 | |
and it was a balmy -5 degrees centigrade. | 0:13:44 | 0:13:47 | |
It's only -5 in here, it was -25 in Antarctica! This is easy! | 0:13:47 | 0:13:52 | |
So, Katie, why go to the extreme of visiting Antarctica | 0:13:52 | 0:13:57 | |
-to look for your meteorites? -Antarctica's a desert. | 0:13:57 | 0:14:00 | |
It has very little rainfall and precipitation, | 0:14:00 | 0:14:02 | |
which means that the meteorites that are found there | 0:14:02 | 0:14:05 | |
are very well preserved. | 0:14:05 | 0:14:06 | |
Also there are no trees, no buildings... | 0:14:06 | 0:14:08 | |
It's easy to find a nice big black meteorite sitting on the white ice, | 0:14:08 | 0:14:13 | |
so it's kind of an easy thing to do. | 0:14:13 | 0:14:15 | |
This is a good example of the dark meteorites | 0:14:15 | 0:14:17 | |
that would be sitting on the ice. | 0:14:17 | 0:14:19 | |
Are there particularly good places to look for meteorites on Antarctica? | 0:14:19 | 0:14:23 | |
There are. | 0:14:23 | 0:14:24 | |
Meteorites fall randomly all over Antarctica as they do the rest of the world, | 0:14:24 | 0:14:28 | |
but what happens is that the ice on the polar plateau | 0:14:28 | 0:14:31 | |
flows out towards the edge of the continent | 0:14:31 | 0:14:34 | |
and when it hits the mountain ranges, | 0:14:34 | 0:14:37 | |
the ice is brought up to the surface | 0:14:37 | 0:14:38 | |
and so we find natural concentration sites, | 0:14:38 | 0:14:42 | |
typically along the big mountain ranges, | 0:14:42 | 0:14:44 | |
such as the Transantarctic Mountains. | 0:14:44 | 0:14:46 | |
It's cold enough being in here, | 0:14:46 | 0:14:48 | |
working in Antarctica | 0:14:48 | 0:14:50 | |
must have been incredibly challenging. Tell me about your experience. | 0:14:50 | 0:14:53 | |
I was there for six weeks on the ice, a very remote area, | 0:14:53 | 0:14:56 | |
and every day we'd get up and if the weather was good enough | 0:14:56 | 0:14:59 | |
we would go out and search. | 0:14:59 | 0:15:00 | |
Sometimes if you have a lot of snow or it's very windy - | 0:15:00 | 0:15:03 | |
Antarctica's completely unpredictable - | 0:15:03 | 0:15:05 | |
you get stuck in the tent which is frustrating, | 0:15:05 | 0:15:08 | |
cos all you want to do is go out and find more meteorites. | 0:15:08 | 0:15:10 | |
It's hard work, but when you find them, it's a great award. | 0:15:10 | 0:15:13 | |
Antarctica is still a rich source of meteorites | 0:15:14 | 0:15:18 | |
with more science visits planned in the future. | 0:15:18 | 0:15:21 | |
Every meteorite, it seems, has a story of its own. | 0:15:21 | 0:15:25 | |
This is the largest meteorite in the museum's collection from Cranborne | 0:15:29 | 0:15:32 | |
in Australia and at three-and-a-half tons, | 0:15:32 | 0:15:35 | |
it weighs the same as four cars. | 0:15:35 | 0:15:38 | |
It's an impressive beast and it is older than the Earth. | 0:15:38 | 0:15:41 | |
But, we have some impressive meteorites in Britain too | 0:15:41 | 0:15:44 | |
and Jon has been on the trail of one of them. | 0:15:44 | 0:15:46 | |
This one may have been carried along by a glazier and it even | 0:15:46 | 0:15:50 | |
attracted the interest of prehistoric man, | 0:15:50 | 0:15:52 | |
but it was rediscovered sitting on someone's doorstep. | 0:15:52 | 0:15:56 | |
This is the Iron Age hill fort at Barbury Castle near Swindon, | 0:15:59 | 0:16:04 | |
first occupied some 2,500 years ago. | 0:16:04 | 0:16:07 | |
And what a wonderfully atmospheric and peaceful place this is. | 0:16:11 | 0:16:16 | |
There's a real air of mystery around here. | 0:16:16 | 0:16:19 | |
And all around you can see the remnants of the influence | 0:16:19 | 0:16:23 | |
of ancient man - this Iron Age fort, burial mounds, and it brings to mind | 0:16:23 | 0:16:27 | |
those stories of those Victorian amateur archaeologists who used | 0:16:27 | 0:16:31 | |
to love to explore and dig things up and whatever they found fascinating | 0:16:31 | 0:16:36 | |
or just liked the look of, they would take home to their collections. | 0:16:36 | 0:16:39 | |
This old photograph from Country Life in 1908 is of the Lake House mansion | 0:16:41 | 0:16:46 | |
in Wiltshire, once owned by the Rev Edward Duke. | 0:16:46 | 0:16:50 | |
He was known to excavate local burial grounds, | 0:16:50 | 0:16:54 | |
keeping any interesting pieces for his own private collection. | 0:16:54 | 0:16:57 | |
On the doorstep is certainly something very interesting. | 0:16:57 | 0:17:01 | |
It's the Lake House meteorite. | 0:17:01 | 0:17:02 | |
Here at the Salisbury and South Wiltshire Museum, | 0:17:03 | 0:17:07 | |
I met up with Professor Colin Pillinger. | 0:17:07 | 0:17:10 | |
'He's become a meteorite detective and he's been piecing together | 0:17:10 | 0:17:13 | |
'the history of the Lake House meteorite.' | 0:17:13 | 0:17:16 | |
-Ah! There it is. The Lake House meteorite. -Indeed. You can't miss it. | 0:17:18 | 0:17:23 | |
-It's a fair size, isn't it? -Well, | 0:17:23 | 0:17:26 | |
-it is 92.5 kilograms. -Wow! | 0:17:26 | 0:17:29 | |
But this is not only the BIGGEST British meteorite that we | 0:17:29 | 0:17:31 | |
know about, it is also the one that has been longest on Earth | 0:17:31 | 0:17:36 | |
and it was when we made that measurement that all of us | 0:17:36 | 0:17:39 | |
suddenly realised we had something quite exciting. | 0:17:39 | 0:17:41 | |
So how old exactly is this meteorite | 0:17:41 | 0:17:44 | |
and how long has it been on the Earth? | 0:17:44 | 0:17:47 | |
It's technically 4.5, 4.6 billion years old. | 0:17:47 | 0:17:50 | |
It's been on Earth 32,000 years | 0:17:50 | 0:17:53 | |
but to try and explain how it survived 32,000 years, | 0:17:53 | 0:17:57 | |
you have to tease some facts out of it. | 0:17:57 | 0:18:00 | |
32,000 years ago on Salisbury Plain, | 0:18:00 | 0:18:03 | |
the place was covered in ice. | 0:18:03 | 0:18:05 | |
We're confident that we know meteorites survive very well in ice, | 0:18:05 | 0:18:09 | |
because we collect lots of meteorites on Antarctica. | 0:18:09 | 0:18:13 | |
How do you explain the next bit? | 0:18:13 | 0:18:15 | |
Bronze Age people living on Salisbury Plain, | 0:18:15 | 0:18:18 | |
sort of 4,000 years ago | 0:18:18 | 0:18:21 | |
were building mounds to bury their important people. | 0:18:21 | 0:18:26 | |
The meteorite was then put into one of these barrows. | 0:18:26 | 0:18:29 | |
The majority of the rock that they used would have been chalk. | 0:18:29 | 0:18:32 | |
You've these lovely pictures of the meteorite on the step, you see | 0:18:32 | 0:18:36 | |
the patches of chalk still on the meteorite, | 0:18:36 | 0:18:39 | |
so it clearly was packed somewhere closely associated with chalk. | 0:18:39 | 0:18:44 | |
Colin believes that after it was dug up, the meteorite must have | 0:18:44 | 0:18:48 | |
been kept inside, protected in Edward Duke's collection. | 0:18:48 | 0:18:51 | |
But after his death, it was demoted to the doorstep, | 0:18:51 | 0:18:55 | |
possibly used for kicking off mud from gentlemen's boots. | 0:18:55 | 0:18:59 | |
Since then the chalk has washed off and you look at the meteorite now | 0:18:59 | 0:19:03 | |
and there's no chalk there. | 0:19:03 | 0:19:05 | |
So it can't have been out on that step for more than about 100 years. | 0:19:05 | 0:19:09 | |
So the story goes, 32,000 years ago, a meteorite fell in Britain | 0:19:09 | 0:19:15 | |
and was preserved in a glacier. | 0:19:15 | 0:19:17 | |
Then, used by Bronze Age man to build his burial mound | 0:19:17 | 0:19:21 | |
and dug up by a Victorian archaeologist. | 0:19:21 | 0:19:24 | |
Using a series of clues, Colin has revealed an extraordinary tale | 0:19:24 | 0:19:28 | |
about an extraordinary meteorite. | 0:19:28 | 0:19:31 | |
A wonderful piece of serendipity. | 0:19:32 | 0:19:35 | |
-The needle left the haystack and made its way to you. -Absolutely. | 0:19:35 | 0:19:38 | |
Science is a lot of serendipity. | 0:19:38 | 0:19:41 | |
Such good fun. | 0:19:41 | 0:19:43 | |
We hope that serendipity will play a part tonight. | 0:19:47 | 0:19:51 | |
We're back at Barbury Castle to look for comet Panstarrs, | 0:19:56 | 0:20:00 | |
which we hope to see in a couple of hours. | 0:20:00 | 0:20:03 | |
Pete, Paul and Chris North are here too. | 0:20:03 | 0:20:07 | |
The sky is fairly clear and we're hopeful. | 0:20:07 | 0:20:11 | |
But this comet is low down and very faint. | 0:20:11 | 0:20:14 | |
We're joined by the Wiltshire Astronomical Society | 0:20:14 | 0:20:16 | |
to look for it and last night, | 0:20:16 | 0:20:18 | |
member Pete Glastonbury saw the comet | 0:20:18 | 0:20:20 | |
and what a bonny comet it is too! | 0:20:20 | 0:20:23 | |
Let's hope we'll be as lucky tonight. | 0:20:23 | 0:20:25 | |
We're waiting for the darkness to fall | 0:20:29 | 0:20:32 | |
and when we first arrived, it was awful, wasn't it? | 0:20:32 | 0:20:35 | |
-It was and it has cleared, I have to say. -It has. -Extremely lucky. | 0:20:35 | 0:20:39 | |
This is rare on a Sky At Night shoot! | 0:20:39 | 0:20:41 | |
We are also joined by some of our beginner astronomers... | 0:20:41 | 0:20:45 | |
Peta and Steve Bosley and Christina Chester. | 0:20:45 | 0:20:48 | |
They've come to pick up some tips about observing Saturn, | 0:20:48 | 0:20:52 | |
which is in our April night sky... | 0:20:52 | 0:20:55 | |
Rising around 10pm at the beginning of the month | 0:20:55 | 0:20:58 | |
and getting earlier as the month goes on. | 0:20:58 | 0:21:01 | |
-Have you ever seen Saturn through your telescope? -No, just Jupiter. | 0:21:01 | 0:21:04 | |
Well, you are in for a real treat with Saturn because it's a stunner. | 0:21:04 | 0:21:08 | |
That's the planet which actually hooked me into astronomy. | 0:21:08 | 0:21:11 | |
-How do you find Saturn? -OK, well, you know what The Plough looks like? | 0:21:11 | 0:21:16 | |
-Yep. -You know the handle of The Plough? | 0:21:16 | 0:21:19 | |
If you follow the curve of that away from the blade bit, | 0:21:19 | 0:21:23 | |
if you like, or if you carry on the curve round, | 0:21:23 | 0:21:26 | |
it comes to Spica - | 0:21:26 | 0:21:27 | |
the brightest star in Virgo, | 0:21:27 | 0:21:29 | |
and Saturn is off | 0:21:29 | 0:21:30 | |
to the lower left of Spica | 0:21:30 | 0:21:32 | |
and it's about the same brightness. | 0:21:32 | 0:21:33 | |
-D'you reckon we're going to see the comet tonight? -Fingers crossed. | 0:21:34 | 0:21:37 | |
I can't see your fingers crossed in those gloves, but I'll trust you. | 0:21:37 | 0:21:41 | |
So, the reason why Saturn is so good to look at in April | 0:21:42 | 0:21:46 | |
is because it's at opposition and when a planet is at opposition, | 0:21:46 | 0:21:49 | |
then this is the best time to look at it. | 0:21:49 | 0:21:51 | |
We thought we'd do a little demonstration to demonstrate the opposition. | 0:21:51 | 0:21:56 | |
You are going to be the sun. Peta, you'll be the sun. | 0:21:56 | 0:21:59 | |
Steve, you can be the Earth. Can I ask you to stand here, please? | 0:21:59 | 0:22:02 | |
-Of course. -There we are, you are the planet Earth. | 0:22:02 | 0:22:06 | |
I shall represent Saturn, a ringless Saturn. So this is opposition. | 0:22:06 | 0:22:12 | |
It is when the sun and the planet in question | 0:22:12 | 0:22:15 | |
are at opposite sides of the Earth. | 0:22:15 | 0:22:17 | |
We have the sun in one part of the sky | 0:22:17 | 0:22:20 | |
and in the opposite direction of the sky we have the planet Saturn. | 0:22:20 | 0:22:23 | |
How many moons does Saturn...? | 0:22:25 | 0:22:27 | |
It's got loads of moons, | 0:22:27 | 0:22:28 | |
but most of them are too faint to be seen with a small telescope. | 0:22:28 | 0:22:32 | |
But there is a good family of them that go around the planet itself. | 0:22:32 | 0:22:36 | |
More than you would see with Jupiter. | 0:22:36 | 0:22:38 | |
They are always in attendance | 0:22:38 | 0:22:40 | |
and they are really worth | 0:22:40 | 0:22:41 | |
looking out for as well. | 0:22:41 | 0:22:43 | |
JON: The darkness and the cold is enveloping us | 0:22:48 | 0:22:52 | |
but this Iron Age fort feels really quite magical. | 0:22:52 | 0:22:56 | |
OK, we've got Neil and Hillary here and you're locals? | 0:22:58 | 0:23:02 | |
-Yes, we're from Devizes. -Have you had any luck finding the comet? | 0:23:02 | 0:23:05 | |
No, so we're hopeful that we'll see it tonight. | 0:23:05 | 0:23:08 | |
I think we're all hopeful. Kids, what do you guys get out of it? | 0:23:08 | 0:23:11 | |
-I like planets and space stations and stuff! -Planets are good. | 0:23:11 | 0:23:15 | |
I like seeing all the galaxies and the stars and things. | 0:23:15 | 0:23:18 | |
I think the comet is currently hiding in a bank of cloud | 0:23:20 | 0:23:25 | |
and comets are really delicate things in the night sky | 0:23:25 | 0:23:28 | |
so when you get any haze, particularly in a bright sky | 0:23:28 | 0:23:30 | |
like we've got now, it just washes them out completely. | 0:23:30 | 0:23:33 | |
It's like a comet filter! | 0:23:33 | 0:23:36 | |
JON: While we wait in hope for the stubborn clouds to | 0:23:36 | 0:23:40 | |
clear from the horizon, it is time for our Space Surgery. | 0:23:40 | 0:23:45 | |
Now, the first in a new feature on the Sky At Night. | 0:23:45 | 0:23:48 | |
It is our Space Surgery, where we shall do our very best to | 0:23:48 | 0:23:52 | |
answer the astronomical questions that you may have. | 0:23:52 | 0:23:55 | |
Our first question comes from Mary Pont of Cambridgeshire | 0:23:55 | 0:24:00 | |
and she lives in a bungalow, quite low down. | 0:24:00 | 0:24:03 | |
She's not got a telescope, just her own eyes | 0:24:03 | 0:24:06 | |
and a pair of 750 binoculars. So is there anything that she can look for? | 0:24:06 | 0:24:11 | |
The best thing to do, Mary, is to find your way around the rest | 0:24:11 | 0:24:14 | |
of the sky, so get yourself a night sky guide, perhaps. | 0:24:14 | 0:24:17 | |
Mary's binoculars aren't too dissimilar to the ones | 0:24:17 | 0:24:19 | |
I am holding here. | 0:24:19 | 0:24:20 | |
They're great for hunting for star clusters | 0:24:20 | 0:24:23 | |
and there are a few examples of that. | 0:24:23 | 0:24:25 | |
One of the ones with a chart on our website is the M44, | 0:24:25 | 0:24:27 | |
the Beehive Cluster or Praesepe. | 0:24:27 | 0:24:29 | |
It's a really great place to start, | 0:24:29 | 0:24:31 | |
and looks fabulous in a pair of binoculars like these. | 0:24:31 | 0:24:35 | |
This next question is a great one and I used to wonder this | 0:24:35 | 0:24:37 | |
when I was a lad. | 0:24:37 | 0:24:39 | |
Why are planets, stars and moons perfectly round | 0:24:39 | 0:24:42 | |
and are there any that are not? | 0:24:42 | 0:24:44 | |
So asks Lawrence from Eccles. | 0:24:44 | 0:24:47 | |
It's a very good question | 0:24:47 | 0:24:49 | |
and the answer quite simply is gravity, so once a rocky object | 0:24:49 | 0:24:52 | |
which is what planets, moons and asteroids are made of, | 0:24:52 | 0:24:55 | |
gets more than a few hundred kilometres across in diameter, | 0:24:55 | 0:24:59 | |
then its own self gravity, its own gravitational pull, | 0:24:59 | 0:25:02 | |
its own mass, pulls everything into pretty much a round sphere. | 0:25:02 | 0:25:06 | |
A great example is some of Saturn's moons, | 0:25:06 | 0:25:08 | |
the bigger moons such as Rhea, Titan and Enceladus | 0:25:08 | 0:25:11 | |
are nice, round bodies but some of the smaller ones such as Prometheus | 0:25:11 | 0:25:15 | |
and Pandora are much more odd shapes | 0:25:15 | 0:25:17 | |
because they're too small for gravity to have pulled them. | 0:25:17 | 0:25:21 | |
The next question is from another Chris, Chris Fordham in Huddersfield. | 0:25:22 | 0:25:26 | |
As our galaxy is so vast, is there a simple way to tell | 0:25:26 | 0:25:30 | |
when looking at stars if they are outside our Milky Way? | 0:25:30 | 0:25:35 | |
The simple answer is that all the stars you can see | 0:25:35 | 0:25:38 | |
are our inside our own galaxy. | 0:25:38 | 0:25:39 | |
Measuring distance to objects in astronomy has always been a challenge. | 0:25:39 | 0:25:43 | |
There are various ways of doing it and there was a result out | 0:25:43 | 0:25:46 | |
that we've just measured the distance to one of the nearest galaxies, | 0:25:46 | 0:25:49 | |
the Large Magellanic Cloud through knowing the properties | 0:25:49 | 0:25:53 | |
of those stars in the galaxy themselves | 0:25:53 | 0:25:55 | |
and by determining those, we've measured the distance to that | 0:25:55 | 0:25:57 | |
of 163,000 light years to within an accuracy of one part in 50. | 0:25:57 | 0:26:03 | |
So we are getting much better at measuring distances to stars in other galaxies, | 0:26:03 | 0:26:07 | |
but it is actually something that in astronomy is very hard to do. | 0:26:07 | 0:26:11 | |
If you have a question, we'll do our best to answer it, | 0:26:11 | 0:26:14 | |
so send it to us at... | 0:26:14 | 0:26:16 | |
Well, we didn't actually get to see the comet in the end, | 0:26:24 | 0:26:26 | |
-did we, chaps? -No, we didn't. -But not to worry. | 0:26:26 | 0:26:28 | |
We have a beautiful, clear night here. | 0:26:28 | 0:26:30 | |
It's not the last chance to find it, right? | 0:26:30 | 0:26:32 | |
No. Comet C2011 L4 Panstarrs | 0:26:32 | 0:26:35 | |
will be in our skies for some time yet. | 0:26:35 | 0:26:39 | |
It's getting fainter as time goes on, | 0:26:39 | 0:26:42 | |
but throughout the month of April, | 0:26:42 | 0:26:44 | |
it'll pass up through Andromeda, through Cassiopeia toward Cepheus. | 0:26:44 | 0:26:49 | |
And it actually goes quite close to the Andromeda galaxy as well. | 0:26:49 | 0:26:53 | |
A good opportunity to pick out the comet still throughout | 0:26:53 | 0:26:56 | |
the month of April. | 0:26:56 | 0:26:58 | |
Sadly it eluded us. | 0:26:58 | 0:27:00 | |
That bank of cloud was like two pub bouncers saying you're not coming in! | 0:27:00 | 0:27:05 | |
We may have been unlucky, but not so for many of you. | 0:27:08 | 0:27:12 | |
Our Flickr site has some amazing images of the comets | 0:27:12 | 0:27:15 | |
from around the world. | 0:27:15 | 0:27:17 | |
You can see the best of them on our website at bbc.co.uk/skyatnight. | 0:27:17 | 0:27:23 | |
We have one more celestial treat. | 0:27:37 | 0:27:40 | |
Lucy and Chris have been allowed | 0:27:40 | 0:27:42 | |
to hold something rather precious. | 0:27:42 | 0:27:44 | |
Well, this is something really special. | 0:27:47 | 0:27:50 | |
This is a piece of Martian meteorite and so this little rock | 0:27:50 | 0:27:53 | |
knew Mars when it was a wet world, travelled out into space | 0:27:53 | 0:27:57 | |
and then ended up here on Earth, where it can tell us its story. | 0:27:57 | 0:28:01 | |
I'm holding the piece of the moon that Anton showed me earlier on. | 0:28:01 | 0:28:03 | |
Trapped in this tiny fragment is the history of the lunar surface | 0:28:03 | 0:28:07 | |
from that area. | 0:28:07 | 0:28:09 | |
A huge thank you to the Natural History Museum for showing us | 0:28:09 | 0:28:12 | |
behind the scenes and allowing us to hold these very special objects. | 0:28:12 | 0:28:15 | |
When we come back next month, we'll be going past the moon, | 0:28:15 | 0:28:19 | |
past Mars and on out to Saturn. | 0:28:19 | 0:28:21 | |
So, until next month... | 0:28:21 | 0:28:22 | |
-BOTH: -Good night. | 0:28:22 | 0:28:24 | |
Subtitles by Red Bee Media Ltd | 0:28:41 | 0:28:44 |