Browse content similar to Lives of the Stars. Check below for episodes and series from the same categories and more!
Line | From | To | |
---|---|---|---|
-BOTH: Hello. -Welcome to Herstmonceux Observatory in East Sussex, | 0:00:33 | 0:00:37 | |
with its collection of impressive | 0:00:37 | 0:00:39 | |
and elegant domes. They still have working telescopes here | 0:00:39 | 0:00:42 | |
and enjoy wonderful dark skies, so I'm told, when it's clear. | 0:00:42 | 0:00:46 | |
Well, we hope to enjoy those dark skies a little later with | 0:00:46 | 0:00:50 | |
the Wealden Astronomical Society, but until then, | 0:00:50 | 0:00:52 | |
we're going to talk about the lives and dramatic deaths of stars. | 0:00:52 | 0:00:55 | |
And the team are here too, having a tug-of-war. | 0:00:55 | 0:00:58 | |
We'll find out why later. | 0:00:58 | 0:01:00 | |
Herstmonceux was built after the Second World War | 0:01:02 | 0:01:06 | |
and became a Royal Observatory in 1958. | 0:01:06 | 0:01:10 | |
Many of the telescopes came from Greenwich, | 0:01:11 | 0:01:13 | |
where the London light pollution had become too much. | 0:01:13 | 0:01:18 | |
Sir Patrick Moore was a regular visitor | 0:01:18 | 0:01:21 | |
and supporter of the observatory, using the telescopes | 0:01:21 | 0:01:24 | |
to look at the moon. Here he is in 1984. | 0:01:24 | 0:01:29 | |
Of course, there are some features of the observatory | 0:01:29 | 0:01:32 | |
which everybody knows. | 0:01:32 | 0:01:33 | |
There is, for example, the time department. | 0:01:33 | 0:01:36 | |
And here, the atomic clocks | 0:01:36 | 0:01:38 | |
are now better timekeepers than the Earth itself. | 0:01:38 | 0:01:40 | |
And it's also from here that the six pips come out. | 0:01:40 | 0:01:43 | |
LOUD PIP | 0:01:43 | 0:01:46 | |
Then there are the telescopes of Herstmonceux, | 0:01:46 | 0:01:48 | |
which is another reason for our being here. | 0:01:48 | 0:01:50 | |
In its heyday, 200 astronomers worked here | 0:01:50 | 0:01:54 | |
and they looked at galaxies, nebula and even comets, | 0:01:54 | 0:01:59 | |
but the majority of their work was with the stars. | 0:01:59 | 0:02:02 | |
They mapped the stars in the sky, measured their distances, brightness | 0:02:02 | 0:02:06 | |
and studied the light to see what the stars are made of. | 0:02:06 | 0:02:10 | |
Stars make up a family and, like any family, | 0:02:12 | 0:02:16 | |
the members are different. | 0:02:16 | 0:02:17 | |
-Some stars are big. -Some small. -Some bright. -And some dim. | 0:02:17 | 0:02:21 | |
But they're all essentially the same. | 0:02:21 | 0:02:23 | |
They're vast balls of gas, mostly hydrogen. | 0:02:23 | 0:02:26 | |
But the best star to look at is our own - the sun. | 0:02:26 | 0:02:29 | |
And that's because, at the core of the sun, we know that | 0:02:29 | 0:02:32 | |
the temperatures and the pressures are almost unimaginably vast. | 0:02:32 | 0:02:35 | |
That means the atoms there are moving incredibly quickly. | 0:02:35 | 0:02:39 | |
And when they collide, they can fuse together and as a consequence | 0:02:39 | 0:02:42 | |
of the most famous equation - e=mc2 - matter is turned into light. | 0:02:42 | 0:02:48 | |
And that happens at a furious rate. In fact, the sun is losing | 0:02:48 | 0:02:52 | |
nearly 4 million tonnes of matter each and every second. | 0:02:52 | 0:02:56 | |
So that's 4 million tonnes gone. | 0:02:56 | 0:02:58 | |
And another 4 million tonnes gone. | 0:02:58 | 0:03:00 | |
And that's happening all the time, in every one | 0:03:00 | 0:03:03 | |
of the hundreds of billions of stars in our own galaxy. | 0:03:03 | 0:03:06 | |
In fact, as stars go, the sun's not much to write home about. | 0:03:06 | 0:03:09 | |
It's rather Mr Average. And so, it's time we met the rest of the family. | 0:03:09 | 0:03:14 | |
There are hundreds of billions of stars in our own galaxy, | 0:03:16 | 0:03:20 | |
but even from a good, dark spot, | 0:03:20 | 0:03:22 | |
you'll have to content yourself with seeing just a few thousand of them. | 0:03:22 | 0:03:26 | |
Even the largest telescopes won't show a star | 0:03:26 | 0:03:29 | |
as anything other than a point of light, but we do see colour. | 0:03:29 | 0:03:33 | |
Some stars are yellow, like our own sun, | 0:03:33 | 0:03:35 | |
some red, and some blue. | 0:03:35 | 0:03:38 | |
And it turns out that colour's important, | 0:03:38 | 0:03:41 | |
because it tells us how hot the stars are. | 0:03:41 | 0:03:43 | |
Lucie and I have come to a telescope | 0:03:45 | 0:03:47 | |
that's spent many a night staring at the stars. | 0:03:47 | 0:03:50 | |
Fantastic. So here we have the 1896 26-inch Thomson Refractor. | 0:03:52 | 0:03:57 | |
-It's beautiful, isn't it? -Fantastic. | 0:03:57 | 0:03:59 | |
Always good to see a proper refractor in a giant dome. | 0:03:59 | 0:04:02 | |
This is what observatories are supposed to look like. | 0:04:02 | 0:04:04 | |
And they used to do measurements of star positions from here. | 0:04:04 | 0:04:07 | |
And not just positions. | 0:04:07 | 0:04:09 | |
This telescope was used to measure the distances to the stars. | 0:04:09 | 0:04:12 | |
But that's not the most interesting thing about this telescope. | 0:04:12 | 0:04:15 | |
It does something really special. Let me show you. Come round here. | 0:04:15 | 0:04:20 | |
-OK, I'm slightly nervous. -SHE LAUGHS | 0:04:20 | 0:04:22 | |
When you start running for...for switches. | 0:04:22 | 0:04:25 | |
-Hold onto your hats. -OK. -Here we go. | 0:04:25 | 0:04:28 | |
LOUD THUD, CHRIS LAUGHS | 0:04:28 | 0:04:31 | |
So we do not have to move the telescope. We go to the telescope. | 0:04:31 | 0:04:34 | |
This is the civilised way to get to your observing position. | 0:04:34 | 0:04:38 | |
Move the entire floor. | 0:04:38 | 0:04:39 | |
-This is fabulous! -LUCIE LAUGHS | 0:04:39 | 0:04:41 | |
-But you need to watch out for your head, Chris. -Right, thank you. | 0:04:41 | 0:04:44 | |
I've been told it stops automatically. I'm just going | 0:04:44 | 0:04:46 | |
-to keep pressing until it does. -Are you sure this stops? | 0:04:46 | 0:04:49 | |
I'm willing... Yes! | 0:04:49 | 0:04:51 | |
-There we go. -There we go. -Perfect. | 0:04:51 | 0:04:53 | |
-So what a civilised way to get up to do the observing. -It's great. | 0:04:53 | 0:04:56 | |
-And now, here we are and we can go look at the sky. -Yeah, fantastic! | 0:04:56 | 0:04:59 | |
Over 100 years ago, astronomers were trying to make sense | 0:05:02 | 0:05:05 | |
of the assortment of stars in the night sky. | 0:05:05 | 0:05:09 | |
Two men - American Henry Russell and Dane Ejnar Hertzsprung - | 0:05:09 | 0:05:13 | |
realised that the key was showing | 0:05:13 | 0:05:15 | |
how the brightness of a star is related to its colour. | 0:05:15 | 0:05:19 | |
So what we've got here are the two things we know about stars. | 0:05:21 | 0:05:24 | |
We've got their colour, but colour means temperature, | 0:05:24 | 0:05:26 | |
so the red stars are the coolest | 0:05:26 | 0:05:28 | |
and the blue, white ones are the hottest. | 0:05:28 | 0:05:30 | |
It's the opposite way round from bathroom taps. | 0:05:30 | 0:05:32 | |
Red is cool, blue is hot. | 0:05:32 | 0:05:34 | |
And the other piece of information is how bright the star is. | 0:05:34 | 0:05:38 | |
So faint ones go down here | 0:05:38 | 0:05:40 | |
and bright ones go up here. | 0:05:40 | 0:05:42 | |
So now all we need is to put some stars on our board | 0:05:42 | 0:05:45 | |
and, in fact, we've got some in our pocket. | 0:05:45 | 0:05:48 | |
And the first one that we can put on is the most familiar star - the sun. | 0:05:48 | 0:05:51 | |
And it turns out the sun goes bang in the middle of our diagram here. | 0:05:51 | 0:05:55 | |
Surface temperature of about 6,000 Kelvin, | 0:05:55 | 0:05:57 | |
so halfway along here and then, medium brightness as well. | 0:05:57 | 0:06:02 | |
We can also do the brightest star in the sky and that's Sirius. | 0:06:02 | 0:06:06 | |
And Sirius is a bit hotter and a bit brighter than our sun, | 0:06:06 | 0:06:08 | |
so that goes up here. | 0:06:08 | 0:06:10 | |
The nearest star system to our own is made up of Alpha Centauri. | 0:06:10 | 0:06:13 | |
A bit hotter, a bit brighter than the sun. That has a companion, | 0:06:13 | 0:06:16 | |
Alpha Centauri B, which is a bit fainter. | 0:06:16 | 0:06:18 | |
Put it down there. And then, the nearest star to the sun, Proxima, | 0:06:18 | 0:06:22 | |
red, much smaller, much fainter, so that goes down there. | 0:06:22 | 0:06:25 | |
Now, I want to extend it up here a little bit, | 0:06:25 | 0:06:27 | |
so I'm going to put on Spica, which is a staggering 12,000 times | 0:06:27 | 0:06:31 | |
as bright as our sun, but because it's over 200 light-years away, | 0:06:31 | 0:06:35 | |
it's a little bit fainter, how we see it, | 0:06:35 | 0:06:37 | |
but it is bright in reality and it goes up here. | 0:06:37 | 0:06:40 | |
And lots of our familiar bright stars in the night sky go here, | 0:06:40 | 0:06:43 | |
so Vega sits about there as well. | 0:06:43 | 0:06:45 | |
And then, if we add a few more stars, | 0:06:45 | 0:06:47 | |
we begin to see that they fill in the gaps. | 0:06:47 | 0:06:49 | |
And actually, what's really clear is that all the stars lie along | 0:06:49 | 0:06:54 | |
one line in our diagram and that tells us something really important. | 0:06:54 | 0:06:57 | |
They're all fusing hydrogen to helium in their cores. | 0:06:57 | 0:07:01 | |
That's what's powering them. | 0:07:01 | 0:07:02 | |
It's what we astronomers call the main sequence. | 0:07:05 | 0:07:09 | |
But not all stars sit here. | 0:07:09 | 0:07:12 | |
There are hot bright stars called blue giants, like Deneb, | 0:07:12 | 0:07:16 | |
and then there are the red giants, like Arcturus, | 0:07:16 | 0:07:19 | |
which our sun will become in its old age. | 0:07:19 | 0:07:21 | |
These fuse helium at their core | 0:07:23 | 0:07:25 | |
causing them to swell to enormous proportions. | 0:07:25 | 0:07:28 | |
It's hard to get your head round the sizes of the stars, | 0:07:30 | 0:07:33 | |
but luckily, I've got an onion and I want you to imagine | 0:07:33 | 0:07:36 | |
that this onion is the size of the sun as it is today. | 0:07:36 | 0:07:39 | |
But the sun won't stay that size forever. | 0:07:39 | 0:07:41 | |
When it turns into a red giant 4,500 million years from now, | 0:07:41 | 0:07:45 | |
it will swell up from the size of the onion | 0:07:45 | 0:07:48 | |
to be the size of the dome and that will encompass the Earth's orbit. | 0:07:48 | 0:07:52 | |
And if that's not impressive enough, Betelgeuse, | 0:07:52 | 0:07:54 | |
one of the biggest of the stars, | 0:07:54 | 0:07:56 | |
so large - ten times larger in fact than Jupiter's orbit - | 0:07:56 | 0:08:00 | |
would fit inside it. | 0:08:00 | 0:08:01 | |
Stars don't collapse because of pressure from the core, | 0:08:03 | 0:08:06 | |
pushing up against gravity. | 0:08:06 | 0:08:08 | |
As the star grows old, these two forces strain against each other, | 0:08:09 | 0:08:13 | |
rather like a tug-of-war. | 0:08:13 | 0:08:15 | |
JON CULSHAW, LIKE A BBC SPORTS COMMENTATOR: 'And you join us here | 0:08:15 | 0:08:18 | |
'for our stellar tug-of-war! We have two teams, Team Gravity, | 0:08:18 | 0:08:21 | |
'an ever present force, trying to pull everything inwards! | 0:08:21 | 0:08:25 | |
'And then, there is Team Star, which has energy and pressure on its side, | 0:08:25 | 0:08:30 | |
'resisting the pull of gravity. Team Star is nuclear! | 0:08:30 | 0:08:33 | |
'They are burning hydrogen and you can feel the heat! | 0:08:33 | 0:08:37 | |
'Team Gravity, though, they never give up. | 0:08:38 | 0:08:40 | |
'They are a force to be reckoned with!' | 0:08:40 | 0:08:43 | |
We stand a better chance of survival if we work together. | 0:08:44 | 0:08:48 | |
'Team Star, quite magnificent, producing just enough heat and light | 0:08:53 | 0:08:58 | |
'to balance gravity! Absolute stalemate here! | 0:08:58 | 0:09:00 | |
TEAMS GRUNT | 0:09:00 | 0:09:03 | |
'But Team Star running out of steam! The hydrogen has all but gone here! | 0:09:03 | 0:09:07 | |
'They are beginning to collapse! | 0:09:07 | 0:09:10 | |
'Team Gravity sensing success here, surely!' | 0:09:10 | 0:09:13 | |
LOUD GRUNTING | 0:09:14 | 0:09:16 | |
'But, but, hang on a minute, deep in the core, things are heating up here! | 0:09:16 | 0:09:20 | |
'Team Star are fighting right back. Suddenly, they're right back in it, | 0:09:20 | 0:09:23 | |
'burning helium, a surge in the energy! Team Star is now a red giant | 0:09:23 | 0:09:28 | |
'and the crowd love it!' CHEERING | 0:09:28 | 0:09:30 | |
'Gravity on the run here, you would have to say, Derek! | 0:09:30 | 0:09:33 | |
'But hold on a minute! Team Star has spent their fuel. | 0:09:33 | 0:09:36 | |
'They have burned up. They're all gone. Nothing left. | 0:09:36 | 0:09:40 | |
'And Gravity continues pulling in and the star collapses. | 0:09:40 | 0:09:44 | |
'It becomes a quite spectacular nebula | 0:09:44 | 0:09:48 | |
'with a tiny white dwarf at its heart. | 0:09:48 | 0:09:50 | |
'Gravity wins the day! Remarkable.' | 0:09:50 | 0:09:53 | |
Eventually, the outer layers of the sun will be expelled into space, | 0:09:56 | 0:10:01 | |
becoming a planetary nebula. | 0:10:01 | 0:10:03 | |
The core, called a white dwarf, | 0:10:03 | 0:10:05 | |
will be all that remains of our once mighty star. | 0:10:05 | 0:10:09 | |
We see lots of planetary nebulae in our night sky. | 0:10:09 | 0:10:13 | |
They are beautiful and ephemeral. The death of a star caught in time. | 0:10:13 | 0:10:19 | |
The most massive stars, | 0:10:19 | 0:10:21 | |
like hot blue Deneb, don't die quietly. | 0:10:21 | 0:10:24 | |
Once their fuel is consumed, | 0:10:24 | 0:10:26 | |
the star collapses | 0:10:26 | 0:10:28 | |
and the result is one of the most violent explosions in the universe. | 0:10:28 | 0:10:32 | |
We call it a supernova. | 0:10:32 | 0:10:35 | |
These cataclysmic stellar deaths can outshine an entire galaxy, | 0:10:40 | 0:10:45 | |
and, in 1987, we were treated to one in a galaxy on our cosmic doorstep | 0:10:45 | 0:10:50 | |
in the nearby Large Magellanic Cloud. | 0:10:50 | 0:10:52 | |
The object, called Supernova 1987A, | 0:10:54 | 0:10:57 | |
has been studied in great detail ever since, | 0:10:57 | 0:10:59 | |
and astronomers have watched the glowing rings of material | 0:10:59 | 0:11:03 | |
spreading out into the cosmos. | 0:11:03 | 0:11:05 | |
You can see the remnants of supernovae in the night sky | 0:11:09 | 0:11:12 | |
with even a moderately-sized telescope. | 0:11:12 | 0:11:15 | |
Nearly 1,000 years ago, | 0:11:17 | 0:11:19 | |
a blue giant star exploded in the constellation of Taurus. | 0:11:19 | 0:11:23 | |
And we see it today as the Crab Nebula. | 0:11:23 | 0:11:26 | |
The astronomers at Herstmonceux studied these objects and many more. | 0:11:29 | 0:11:34 | |
And Jon's been finding out what it was like to work here. | 0:11:34 | 0:11:37 | |
Life for an astronomer at Herstmonceux was busy, | 0:11:40 | 0:11:43 | |
observing by night and day. | 0:11:43 | 0:11:46 | |
With all the telescopes working at night-time in the Sussex countryside, | 0:11:46 | 0:11:50 | |
it must have been an active and exciting place to be. | 0:11:50 | 0:11:52 | |
But there was time for some R and R, | 0:11:54 | 0:11:55 | |
with some interesting accommodation next door. | 0:11:55 | 0:11:58 | |
Not every astronomer gets the chance to sleep in a 15th-century castle. | 0:11:58 | 0:12:03 | |
The observatories were purpose built to fit in with the castle setting. | 0:12:03 | 0:12:08 | |
A flint knapper was brought out of retirement to finish the outsides | 0:12:08 | 0:12:12 | |
and the copper domes finished in verdigris. | 0:12:12 | 0:12:15 | |
But unfortunately, all the effort building this magnificent facility | 0:12:15 | 0:12:19 | |
couldn't improve the British weather. Almost as soon as it was finished, | 0:12:19 | 0:12:23 | |
plans were afoot to move to the Canary Islands, | 0:12:23 | 0:12:25 | |
where the seeing was better and, by 1990, the observatory closed. | 0:12:25 | 0:12:30 | |
Dr Graham Appleby was a solar observer here. | 0:12:31 | 0:12:35 | |
So, Graham, you worked here from 1970 to 1990. | 0:12:37 | 0:12:41 | |
Really the heyday of Herstmonceux as a Royal Observatory. | 0:12:41 | 0:12:45 | |
What are some of your most memorable observations | 0:12:45 | 0:12:48 | |
and studies that would have happened during that time? | 0:12:48 | 0:12:51 | |
I began observing the sun. | 0:12:51 | 0:12:53 | |
My first job was looking | 0:12:53 | 0:12:55 | |
at the sunspots through hydrogen-alpha filters | 0:12:55 | 0:12:57 | |
and flares. It was a very active time in the sun, | 0:12:57 | 0:13:00 | |
so it was amazing to see, from the ground, these sunspots erupting. | 0:13:00 | 0:13:05 | |
Then I got involved in observing the moon, | 0:13:05 | 0:13:07 | |
the passage of the moon across in front of stars, | 0:13:07 | 0:13:09 | |
so looking at that was very exciting as well. | 0:13:09 | 0:13:11 | |
And as observatories go, it's a very beautiful place. | 0:13:11 | 0:13:14 | |
-Yes. -Wonderfully landscaped and so on. | 0:13:14 | 0:13:16 | |
But some of the astronomers, in the early days that this was crafted, | 0:13:16 | 0:13:19 | |
were a little sceptical about that. | 0:13:19 | 0:13:21 | |
-You don't need a pond when you're studying the stars at night. -Exactly. | 0:13:21 | 0:13:24 | |
Imagine this completely dark, some little lights may be glowing, | 0:13:24 | 0:13:26 | |
but you come out of this dome up here, | 0:13:26 | 0:13:28 | |
which I worked in quite a lot, Dome D, it has a 10 centimetre refractor. | 0:13:28 | 0:13:33 | |
We used to use it to observe minor planets. | 0:13:33 | 0:13:36 | |
And you can imagine coming out of the steps there and, | 0:13:36 | 0:13:38 | |
if you make a wrong turn, you're in the pond. | 0:13:38 | 0:13:41 | |
So it's not the best design. | 0:13:41 | 0:13:43 | |
It looks great, but it's not the best design for a dark observatory. | 0:13:43 | 0:13:47 | |
But now, Herstmonceux is this wonderful visitor centre | 0:13:48 | 0:13:52 | |
and scientific centre and a great place for astronomy outreach. | 0:13:52 | 0:13:55 | |
Lots of people being inspired as they visit here, | 0:13:55 | 0:13:58 | |
so sort of a new kind of heyday, isn't it now? | 0:13:58 | 0:14:01 | |
Yes, to see these older telescopes now being used for education | 0:14:01 | 0:14:04 | |
is a perfect link, actually, is a perfect result. | 0:14:04 | 0:14:07 | |
Patrick himself was a great, great fan of this place. | 0:14:07 | 0:14:10 | |
So I'm sure he'd be delighted to see it | 0:14:10 | 0:14:12 | |
as this great centre of outreach for astronomy, | 0:14:12 | 0:14:14 | |
sparking new interests in astronomy all the time as people visit. | 0:14:14 | 0:14:18 | |
The observatory here shone brightly, but all too briefly. | 0:14:21 | 0:14:25 | |
'Chris North and I are going to see | 0:14:29 | 0:14:31 | |
'how they used to study the light from stars.' | 0:14:31 | 0:14:35 | |
Here, we've got the largest telescope on the site - | 0:14:35 | 0:14:38 | |
the 36 inch yapp reflector. | 0:14:38 | 0:14:41 | |
It's built in the 1930s, moved here in the '50s, | 0:14:41 | 0:14:43 | |
and it's quite a remarkable feat of engineering, isn't it? | 0:14:43 | 0:14:46 | |
It is wonderfully imposing to see it, really arresting as you walk in. | 0:14:46 | 0:14:50 | |
This, of course, adapted for spectroscopy, | 0:14:50 | 0:14:52 | |
so it can decode and specifically study starlight and really tell us | 0:14:52 | 0:14:57 | |
about the signature of stars and show us their uniqueness. | 0:14:57 | 0:15:00 | |
So you can do this with a prism, split the sun's light, or you can | 0:15:00 | 0:15:04 | |
-even create the same effect using the back of a CD. -Exactly. | 0:15:04 | 0:15:07 | |
But to see the light from other stars that are fainter than the sun, | 0:15:07 | 0:15:10 | |
you've actually got to use a telescope like this to | 0:15:10 | 0:15:12 | |
collect enough light, because they are so much fainter than the sun. | 0:15:12 | 0:15:15 | |
When we do that, we see something quite remarkable in the spectrum. | 0:15:15 | 0:15:18 | |
-I imagine this would collect rather a lot of light. -Yes. | 0:15:18 | 0:15:20 | |
-And give us the chance that we could study it over here. -Indeed. | 0:15:20 | 0:15:23 | |
Ah! There was one of these on Mr Dwyer's laboratory wall at school. | 0:15:24 | 0:15:28 | |
They're very decorative, but what do they tell us? | 0:15:28 | 0:15:31 | |
This is the sun, right? | 0:15:31 | 0:15:32 | |
So this is a representation of the light from the sun, | 0:15:32 | 0:15:36 | |
split out into its rainbow, its spectrum of colours. | 0:15:36 | 0:15:39 | |
And it goes from red through purple, as you might expect, | 0:15:39 | 0:15:42 | |
but there are specific colours that appear much darker | 0:15:42 | 0:15:45 | |
and that's because those very specific colours, like this one, | 0:15:45 | 0:15:49 | |
absorbed by specific types of elements in the sun's atmosphere, | 0:15:49 | 0:15:52 | |
so this one, in the red end of the spectrum, | 0:15:52 | 0:15:55 | |
is absorbed by hydrogen in the sun's atmosphere | 0:15:55 | 0:15:58 | |
and there are other elements as well, so hydrogen absorbs | 0:15:58 | 0:16:00 | |
at this wavelength and other wavelengths as well. But we can | 0:16:00 | 0:16:03 | |
also see that there's small amounts of calcium in the sun's atmosphere | 0:16:03 | 0:16:07 | |
and the small amounts of iron in the sun's atmosphere. | 0:16:07 | 0:16:09 | |
We can start to get a spectral fingerprint | 0:16:09 | 0:16:13 | |
-of what the sun is made of. -And the chart above. | 0:16:13 | 0:16:16 | |
Now, this is from a blue giant star. | 0:16:16 | 0:16:18 | |
Some of the lines are in a similar position, | 0:16:18 | 0:16:20 | |
but there's a lot that's different about it. | 0:16:20 | 0:16:22 | |
What differences are we seeing there? | 0:16:22 | 0:16:24 | |
So the first thing about the blue giant star is that | 0:16:24 | 0:16:27 | |
it's very bright in the blue, but it's very dim in the red | 0:16:27 | 0:16:30 | |
and that's because the star is much hotter. | 0:16:30 | 0:16:32 | |
The fact that the star's a lot hotter also means that | 0:16:32 | 0:16:34 | |
some of those elements in the atmosphere | 0:16:34 | 0:16:36 | |
are completely stripped of their electrons already. | 0:16:36 | 0:16:39 | |
Now that means they can't absorb any light, | 0:16:39 | 0:16:41 | |
so we don't see absorption lines, as these are called, | 0:16:41 | 0:16:45 | |
from iron and from calcium and that kind of thing. | 0:16:45 | 0:16:48 | |
We mainly just see hydrogen in the atmospheres of those stars. | 0:16:48 | 0:16:52 | |
So we had the diagram - the HertzsprungRussell diagram | 0:16:52 | 0:16:55 | |
that Chris and Lucie were showing us earlier - | 0:16:55 | 0:16:57 | |
and we had the sun right in the middle, | 0:16:57 | 0:17:00 | |
and the hot blue stars up on the top left, | 0:17:00 | 0:17:02 | |
then, down the bottom right, we had the cold red stars. | 0:17:02 | 0:17:05 | |
And this is one of those cooler red stars. | 0:17:05 | 0:17:08 | |
We can see that it's very bright in the red | 0:17:08 | 0:17:10 | |
and it's much fainter in the blue. That tells us it's much cooler. | 0:17:10 | 0:17:13 | |
But also, the spectrum's a lot busier. | 0:17:13 | 0:17:16 | |
There's an awful lot more lines in there. | 0:17:16 | 0:17:18 | |
And whereas the atmospheres of these stars, these warmer stars, | 0:17:18 | 0:17:21 | |
are dominated just by atoms in their atmospheres, | 0:17:21 | 0:17:24 | |
in cooler stars, you can have molecules. You can have chemistry. | 0:17:24 | 0:17:27 | |
This is atoms joined together. Molecules absorb light | 0:17:27 | 0:17:30 | |
at many, many more colours than just the pure atoms do. | 0:17:30 | 0:17:34 | |
And if you go to even colder temperatures too, | 0:17:34 | 0:17:36 | |
things get even more complex, | 0:17:36 | 0:17:38 | |
because not only do you get redder and redder | 0:17:38 | 0:17:41 | |
until you're almost invisible to the light we see with our eyes, | 0:17:41 | 0:17:45 | |
not only do you have molecules and chemistry in the atmosphere, | 0:17:45 | 0:17:48 | |
you get something you really wouldn't expect. You get weather. | 0:17:48 | 0:17:51 | |
And you certainly don't associate that taking place on a star | 0:17:51 | 0:17:55 | |
and this takes us to that strange world of the brown dwarf. | 0:17:55 | 0:17:57 | |
A very curious object, sort of like a duck-billed platypus, in a way. | 0:17:57 | 0:18:02 | |
Hard to classify exactly what they are. | 0:18:02 | 0:18:04 | |
-LUCIE: -Brown dwarves are a new addition to our star chart | 0:18:07 | 0:18:11 | |
and are the coolest and dimmest of stars. | 0:18:11 | 0:18:15 | |
Hertzsprung and Russell could only have dreamed | 0:18:15 | 0:18:18 | |
of these strange beasts. | 0:18:18 | 0:18:20 | |
Part of the difficulty has been seeing them, | 0:18:22 | 0:18:25 | |
because they don't shine brightly like our star. | 0:18:25 | 0:18:29 | |
To find them, we need infrared telescopes, | 0:18:29 | 0:18:31 | |
which can pick out cool objects. | 0:18:31 | 0:18:34 | |
'Ben Burningham from the University of Hertfordshire | 0:18:36 | 0:18:39 | |
'is a brown dwarf hunter. | 0:18:39 | 0:18:41 | |
'He uses space telescopes like Spitzer and WISE | 0:18:43 | 0:18:47 | |
'to look for these elusive beasts of the star family, | 0:18:47 | 0:18:51 | |
'which lurk in the cold dark parts of space.' | 0:18:51 | 0:18:54 | |
They're very peculiar objects. | 0:18:54 | 0:18:56 | |
I'm sort of struggling to conceptualise where they sit. | 0:18:56 | 0:18:59 | |
They seem a bit like the missing link in between stars and planets somehow. | 0:18:59 | 0:19:02 | |
They certainly are the missing link between stars and planets. | 0:19:02 | 0:19:05 | |
The warmer ones look a lot like stars. | 0:19:05 | 0:19:07 | |
They show a lot of the behaviour we see stars having, | 0:19:07 | 0:19:09 | |
but then, the lowest mass ones look like planets. | 0:19:09 | 0:19:12 | |
They have weather, for example. You see dust cloud weather and things | 0:19:12 | 0:19:15 | |
at sort of about 1,000 degrees centigrade. | 0:19:15 | 0:19:17 | |
So you go from studying the kind of plasma physics | 0:19:17 | 0:19:20 | |
of charged particles in a stellar atmosphere | 0:19:20 | 0:19:23 | |
with protons and electrons flying around | 0:19:23 | 0:19:25 | |
to atmospheric chemistry, where you're using | 0:19:25 | 0:19:27 | |
the language of planetary science rather than stellar physics. | 0:19:27 | 0:19:31 | |
And what kind of temperatures are we talking about here? | 0:19:31 | 0:19:33 | |
Well, they range from the temperatures of the coolest stars - | 0:19:33 | 0:19:36 | |
at about 1,700 degrees centigrade - to much, much lower temperatures. | 0:19:36 | 0:19:40 | |
In fact, a few years ago, I was very pleased when I pushed the record | 0:19:40 | 0:19:43 | |
along with a team of astronomers at Hertfordshire to down | 0:19:43 | 0:19:46 | |
to about 500 Kelvin, which we thought was about good for oven chips. | 0:19:46 | 0:19:49 | |
Yeah, congratulations on that record. | 0:19:49 | 0:19:51 | |
Well, yeah, it's been taken pretty comprehensively now. | 0:19:51 | 0:19:54 | |
The WISE Mission, a satellite from NASA, | 0:19:54 | 0:19:56 | |
has managed to push the temperature limit down to about 300 Kelvin, | 0:19:56 | 0:19:59 | |
which is room temperature. | 0:19:59 | 0:20:01 | |
-Hang on, room temperature? -Yeah. -Like this temperature? | 0:20:01 | 0:20:04 | |
A bit warmer than this temperature. CHRIS LAUGHS | 0:20:04 | 0:20:06 | |
But, um, but yeah, about 300 Kelvin, 20 degrees centigrade. | 0:20:06 | 0:20:09 | |
So how do you say whether something is a star | 0:20:09 | 0:20:13 | |
-or whether something is a planet? -Well, that's tricky. | 0:20:13 | 0:20:16 | |
So people tend to take a kind of gut feeling approach. | 0:20:16 | 0:20:18 | |
Does the thing taste like a planet, does it smell like a planet? | 0:20:18 | 0:20:21 | |
The definition, officially, is when something is low enough mass | 0:20:21 | 0:20:25 | |
that it doesn't burn something called deuterium in the core | 0:20:25 | 0:20:27 | |
-when it's very young. -Like heavy hydrogen? -Yeah. | 0:20:27 | 0:20:30 | |
Whether it burns that in the core when it's very young, | 0:20:30 | 0:20:32 | |
then we call it a planet if it's orbiting a star. | 0:20:32 | 0:20:34 | |
Um, they have, er, atmospheres that are predominantly | 0:20:34 | 0:20:37 | |
composed of hydrogen, but the molecules we see in the atmosphere, | 0:20:37 | 0:20:41 | |
so things like water, methane and, at the coldest temperatures, ammonia. | 0:20:41 | 0:20:44 | |
And it's probable that, when we get to these temperatures, | 0:20:44 | 0:20:47 | |
we'll start to see water clouds in their atmospheres. | 0:20:47 | 0:20:50 | |
Where are the nearest brown dwarfs? How close are they to us? | 0:20:50 | 0:20:53 | |
Well, they're very close. | 0:20:53 | 0:20:55 | |
In fact, just recently, an American astronomer, working on his own | 0:20:55 | 0:20:58 | |
looking through the WISE dataset, | 0:20:58 | 0:21:00 | |
found a brown dwarf within six light years of Earth, | 0:21:00 | 0:21:03 | |
which makes it one of the closest object to the sun. | 0:21:03 | 0:21:06 | |
-What, the third closest stellar system? -Yeah. -Something like that. | 0:21:06 | 0:21:09 | |
-Yeah. -And we had no idea it was there? -No idea at all. | 0:21:09 | 0:21:11 | |
It was hiding against the crowded background of the galactic plain. | 0:21:11 | 0:21:14 | |
Lots of people have been looking, but it's a very hard job | 0:21:14 | 0:21:17 | |
to find these things and a lot of people were kicking themselves. | 0:21:17 | 0:21:20 | |
It seems slightly careless to have missed a starlike object that close. | 0:21:20 | 0:21:24 | |
Careless is a strong word. LAUGHTER | 0:21:24 | 0:21:26 | |
Sorry, I don't mean to be rude. | 0:21:26 | 0:21:28 | |
-I guess it shows how little we know about the galaxy. -Very hard, yeah. | 0:21:28 | 0:21:31 | |
-So is that the closest one? -That's very hard to say. Um, probably not. | 0:21:31 | 0:21:36 | |
I would say, if we're still finding things at six light years, | 0:21:36 | 0:21:39 | |
there may be things even closer. Um, it would be pretty ambitious | 0:21:39 | 0:21:42 | |
to say that's definitely the closest one. | 0:21:42 | 0:21:45 | |
'The other odd thing about these stars | 0:21:45 | 0:21:48 | |
'is that they don't seem to die.' | 0:21:48 | 0:21:50 | |
They just get colder and colder. | 0:21:50 | 0:21:53 | |
They are immortal stars | 0:21:53 | 0:21:55 | |
ending their lives in the lonely emptiness of space. | 0:21:55 | 0:21:59 | |
We're hoping to see some brighter stars tonight. | 0:22:01 | 0:22:04 | |
Wealden Astronomical Society is resident here | 0:22:04 | 0:22:07 | |
and they've joined us to keep us company. | 0:22:07 | 0:22:10 | |
Paul is talking to John Pilbeam | 0:22:11 | 0:22:13 | |
about some objects we hope to see later. | 0:22:13 | 0:22:17 | |
What sort of area | 0:22:17 | 0:22:19 | |
of amateur astronomy is your particular thing? What grabs you? | 0:22:19 | 0:22:22 | |
Star clusters, and double stars. I love double stars, yeah. | 0:22:22 | 0:22:25 | |
I don't often hear people say that, actually. | 0:22:25 | 0:22:28 | |
-Like the really geeky aspects... -I know. -..of amateur astronomy. | 0:22:28 | 0:22:31 | |
-What's your favourite double star? -Albireo. | 0:22:31 | 0:22:33 | |
-I think we've got to say that. -I have to. -It's quite nice. | 0:22:33 | 0:22:36 | |
Andromeda, I think, has a nice... | 0:22:36 | 0:22:38 | |
is second one to that with the coloured stars, | 0:22:38 | 0:22:40 | |
-but Albireo is the favourite. -The lovely orange and blue. | 0:22:40 | 0:22:43 | |
-It really is. -It is the blue that catches you. | 0:22:43 | 0:22:46 | |
Gary Palmer likes studying my favourite star - our sun. | 0:22:46 | 0:22:51 | |
Pete's finding out why he enjoys solar observing so much. | 0:22:51 | 0:22:55 | |
It's the perfect thing for the public, | 0:22:55 | 0:22:57 | |
-cos it's during the day. -That's right, yeah. It's also nicer for me, | 0:22:57 | 0:23:01 | |
-cos I keep warmer, so, um... -LAUGHTER | 0:23:01 | 0:23:04 | |
-No, I've seen some of your pictures and they are spectacular. -Thank you. | 0:23:04 | 0:23:08 | |
And you specialise particularly | 0:23:08 | 0:23:10 | |
-in what's known as hydrogen alpha imaging... -Yeah. | 0:23:10 | 0:23:13 | |
..which is taking pictures of the sun's chromosphere, | 0:23:13 | 0:23:15 | |
the prominences and whatever going on. | 0:23:15 | 0:23:17 | |
-You've been looking at the sun today, haven't you? -Yeah. | 0:23:17 | 0:23:20 | |
It's been really interesting today. There's some nice detail on there. | 0:23:20 | 0:23:23 | |
I have been fighting with the wind and clouds a little. | 0:23:23 | 0:23:25 | |
-A bit windy, yeah. -Um, but did manage to get some nice images. | 0:23:25 | 0:23:29 | |
-Right, anything particularly stand out? -Yeah, there was a nice flare | 0:23:29 | 0:23:33 | |
that came off the edge of the sun earlier on, | 0:23:33 | 0:23:35 | |
-and gradually developed into a nice loop prominence. -Oh, really? | 0:23:35 | 0:23:38 | |
-They're fantastic! -It was really nice, yeah, lovely to watch. | 0:23:38 | 0:23:41 | |
And there was a lovely large prominence coming off. | 0:23:41 | 0:23:45 | |
That had some fantastic shapes in there. | 0:23:45 | 0:23:48 | |
Um, and also, a lot of sunspots, | 0:23:48 | 0:23:50 | |
so it seems like there's a lot of activity starting again. | 0:23:50 | 0:23:53 | |
-Do you think the sun's starting to wake up a bit? -I think so. | 0:23:53 | 0:23:56 | |
-About time. -Yeah, it's very, very late. | 0:23:56 | 0:23:59 | |
It's a little bit like our summer this year. | 0:23:59 | 0:24:01 | |
JON: So, Paul and Pete, what of the stars in the June sky at the moment? | 0:24:07 | 0:24:12 | |
We're waiting for the clouds to co-operate. It looks like | 0:24:12 | 0:24:14 | |
-more are blowing in. -It doesn't look promising. -Not at the moment, | 0:24:14 | 0:24:17 | |
-but at least June is the time for the noctilucent clouds. -Ah, yes. | 0:24:17 | 0:24:21 | |
-We like those. -We do. -Pete's obsessed with them. | 0:24:21 | 0:24:24 | |
They're great, because the nights in June are really, really short, | 0:24:24 | 0:24:27 | |
so these are things that are easy to see, if they're there. | 0:24:27 | 0:24:30 | |
They glow with an electric blue light, | 0:24:30 | 0:24:33 | |
like a network of clouds in the night sky. | 0:24:33 | 0:24:35 | |
They're really high altitude clouds, they're picking up | 0:24:35 | 0:24:38 | |
the light reflecting off them from the sun, which is below the horizon. | 0:24:38 | 0:24:41 | |
-They're something which are unique to the summertime. -They do have that | 0:24:41 | 0:24:45 | |
-wonderful ethereal glow to them. -They do and the interesting thing is | 0:24:45 | 0:24:48 | |
how subtly they can change over the course of 10-15 minutes. | 0:24:48 | 0:24:51 | |
They really are dynamic objects. Lovely things. | 0:24:51 | 0:24:54 | |
And June also the time of the moon's perigee, | 0:24:54 | 0:24:56 | |
-the super moon, as they call it. -That's right. This is one | 0:24:56 | 0:24:59 | |
of those events that normally gets people very excited, doesn't it? | 0:24:59 | 0:25:03 | |
The moon is going to be | 0:25:03 | 0:25:05 | |
a tiny fraction of a bit larger in the sky. | 0:25:05 | 0:25:07 | |
It's actually 23rd of June and it's because the moon | 0:25:07 | 0:25:10 | |
-is at the closest point in its orbit. -Perigee. | 0:25:10 | 0:25:12 | |
And that coincides with it being full moon this time. | 0:25:12 | 0:25:15 | |
It has the name super moon. That's actually an astrological term. | 0:25:15 | 0:25:18 | |
-We won't have such things here! -Astrologers brought it in. | 0:25:18 | 0:25:21 | |
-Don't mention them again! -Let's say perigee moon. | 0:25:21 | 0:25:23 | |
Well, spectacular as that moon will be, | 0:25:23 | 0:25:25 | |
hopefully it won't wash the stars out too much. | 0:25:25 | 0:25:27 | |
So which particular ones should we be looking out for in June? | 0:25:27 | 0:25:30 | |
Well, the lives and deaths of stars, something we've looked at on the programme. | 0:25:30 | 0:25:34 | |
We've got those in the summer night sky, | 0:25:34 | 0:25:36 | |
so let's start with star clusters and the wild duck cluster, | 0:25:36 | 0:25:40 | |
-M11, is a good one, isn't it? -Lovely, actually. | 0:25:40 | 0:25:42 | |
That's at the bottom of Aquila the eagle. | 0:25:42 | 0:25:44 | |
A little curve of stars points to it. | 0:25:44 | 0:25:46 | |
When you look at it through a telescope... | 0:25:46 | 0:25:49 | |
Even a small telescope will show a beautiful smattering of stars there. | 0:25:49 | 0:25:52 | |
They're supposed to be arranged in a sort of V shape, | 0:25:52 | 0:25:54 | |
which is supposed to look like a cluster of wild ducks | 0:25:54 | 0:25:57 | |
-flying across the sky. -It does look a bit like what it's supposed to. | 0:25:57 | 0:26:00 | |
-One of those rare objects... -You've got a good imagination, | 0:26:00 | 0:26:03 | |
because I've never seen that. | 0:26:03 | 0:26:04 | |
-LAUGHTER -So viewers' imagination! | 0:26:04 | 0:26:07 | |
But we also have a nice globular cluster. | 0:26:07 | 0:26:09 | |
It's low down in the constellation of Sagittarius. | 0:26:09 | 0:26:12 | |
-This is in your teapot asterism, isn't it? -That's right. | 0:26:12 | 0:26:14 | |
It's at the heart of Sagittarius, | 0:26:14 | 0:26:16 | |
which sort of marks the region where the centre of the Milky Way is. | 0:26:16 | 0:26:20 | |
-It looks exactly like a teapot. -Not exactly! -Oh, it does! | 0:26:20 | 0:26:23 | |
It's exactly like a teapot. But if you imagine where steam would | 0:26:23 | 0:26:26 | |
rise out of the spout of the teapot, loads of stuff around there. | 0:26:26 | 0:26:29 | |
You've got the Lagoon Nebula, which is one of only two | 0:26:29 | 0:26:32 | |
areas of nebulosity you can see with the naked eye in the night sky. | 0:26:32 | 0:26:36 | |
You've got the Trifid Nebula, which is a beautiful thing | 0:26:36 | 0:26:38 | |
to look at through a telescope. Three dark lanes cuts it into three. | 0:26:38 | 0:26:41 | |
And then, you've also got M22, which is the brightest globular cluster | 0:26:41 | 0:26:45 | |
which can be seen from the northern hemisphere, | 0:26:45 | 0:26:48 | |
and you've got M25, which is another beautiful cluster. | 0:26:48 | 0:26:51 | |
-A deep sky treasure trove. -It is, absolutely. | 0:26:51 | 0:26:54 | |
It's a pity it's so low down, that's the only unfortunate thing about it. | 0:26:54 | 0:26:57 | |
Well, at the other end of the spectrum, we have star death, | 0:26:57 | 0:27:00 | |
and this is represented by a fine selection of planetary nebula. | 0:27:00 | 0:27:03 | |
In particular, I think, the Ring Nebula in Lyra | 0:27:03 | 0:27:06 | |
is a really fine example of this. | 0:27:06 | 0:27:07 | |
I think you should try this in London, Jon. | 0:27:07 | 0:27:09 | |
I think that telescope of yours would pick it up. | 0:27:09 | 0:27:11 | |
And if you've got a large enough power, and conditions are good, | 0:27:11 | 0:27:14 | |
you see a sort of ghostly smoke ring in the sky. | 0:27:14 | 0:27:18 | |
Well, there's a fine thing to look out for. June full of promise. | 0:27:18 | 0:27:21 | |
-And, hopefully, some clear skies. -Yes! | 0:27:21 | 0:27:24 | |
Many fine objects to observe in June, so long as the weather co-operates | 0:27:27 | 0:27:31 | |
and you can use Pete's sky charts to help locate them, | 0:27:31 | 0:27:35 | |
including the teapot and its steam, if you like. | 0:27:35 | 0:27:37 | |
Just go to our website... | 0:27:37 | 0:27:39 | |
We have had no luck with the weather and it's even starting to rain. | 0:27:46 | 0:27:51 | |
Wealden Astronomical Society are packing up. | 0:27:51 | 0:27:54 | |
Let's hope, next time, we come and enjoy Herstmonceux's dark skies. | 0:27:54 | 0:28:00 | |
In the meantime, it's just the ducks and us that are left behind | 0:28:00 | 0:28:05 | |
to enjoy this beautiful and atmospheric observatory. | 0:28:05 | 0:28:08 | |
We've had a great time here at Herstmonceux. | 0:28:11 | 0:28:13 | |
It's been wonderful to see these lovely old telescopes. | 0:28:13 | 0:28:17 | |
And when we come back next month, we'll be celebrating | 0:28:17 | 0:28:19 | |
the summer solstice by launching our Moore Moon Marathon. | 0:28:19 | 0:28:22 | |
We've selected some easy-to-find features on the moon | 0:28:22 | 0:28:25 | |
for you to tick off during those warm summer nights. | 0:28:25 | 0:28:28 | |
And so, until next month... | 0:28:28 | 0:28:29 | |
ALL: Good night. | 0:28:29 | 0:28:31 | |
Subtitles by Red Bee Media Ltd | 0:28:42 | 0:28:45 |