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This month, we've come to the Roque de los Muchachos Observatory | 0:00:07 | 0:00:11 | |
on the island of La Palma, in the Canary Islands. | 0:00:11 | 0:00:14 | |
It's home to the largest collection of major telescopes | 0:00:18 | 0:00:21 | |
anywhere in Europe, including this magnificent machine, | 0:00:21 | 0:00:24 | |
the Gran Telescopio Canarias, | 0:00:24 | 0:00:26 | |
the largest steerable optical telescope anywhere in the world. | 0:00:26 | 0:00:30 | |
Over the next few nights, | 0:00:32 | 0:00:34 | |
we'll be putting some of these telescopes through their paces, | 0:00:34 | 0:00:36 | |
as we take a voyage of discovery out through the galaxy and beyond. | 0:00:36 | 0:00:41 | |
A voyage chartered by you. | 0:00:41 | 0:00:43 | |
Last month, we invited you to suggest the objects in the night sky | 0:00:46 | 0:00:50 | |
that you would like to have a much closer look at. | 0:00:50 | 0:00:53 | |
You sent us loads of suggestions. | 0:00:53 | 0:00:55 | |
And we've chosen some of the best | 0:00:57 | 0:00:59 | |
to be imaged by these powerful instruments. | 0:00:59 | 0:01:02 | |
Tonight, we're taking over the telescopes of La Palma. | 0:01:04 | 0:01:08 | |
Welcome to The Sky At Night. | 0:01:08 | 0:01:10 | |
It's amazing. We are actually above the clouds. | 0:01:43 | 0:01:47 | |
When people think of La Palma, they think of sun, sand and sea. | 0:01:47 | 0:01:50 | |
But up here it's quite different. | 0:01:50 | 0:01:53 | |
This site sits 2,400 metres above sea level, on a dormant volcano, | 0:01:53 | 0:01:58 | |
and it's quite cold. | 0:01:58 | 0:02:00 | |
But there's a big compensation. | 0:02:00 | 0:02:02 | |
Viewing conditions up here are amongst the best in the world, | 0:02:02 | 0:02:05 | |
and with virtually no light pollution | 0:02:05 | 0:02:07 | |
and up to 300 clear nights a year, | 0:02:07 | 0:02:10 | |
it's a great place to do observing. | 0:02:10 | 0:02:12 | |
Because of these exceptional conditions, | 0:02:18 | 0:02:21 | |
countries from all over Europe have built telescopes here. | 0:02:21 | 0:02:24 | |
There are over 30 of them on the mountain, | 0:02:27 | 0:02:30 | |
all designed to probe the secrets of the universe in different ways. | 0:02:30 | 0:02:34 | |
The telescope behind is called MAGIC, | 0:02:36 | 0:02:39 | |
and it's designed to look for gamma ray bursts in distant galaxies. | 0:02:39 | 0:02:42 | |
And up there on the hill is the Swedish solar telescope, | 0:02:42 | 0:02:46 | |
which is looking at our local star, the sun. | 0:02:46 | 0:02:49 | |
And dotted across the hillsides, | 0:02:54 | 0:02:57 | |
these large domes contain huge instruments | 0:02:57 | 0:03:00 | |
which can look deep into the universe. | 0:03:00 | 0:03:03 | |
These are the telescopes we'll be using to view your suggestions. | 0:03:03 | 0:03:08 | |
We'll be looking at distant galaxies using the vast GTC, | 0:03:08 | 0:03:13 | |
known to astronomers as GranTeCan. | 0:03:13 | 0:03:15 | |
We'll be joining the hunt for exoplanets around other stars. | 0:03:17 | 0:03:20 | |
And we'll be following Alan Fitzsimmons, | 0:03:22 | 0:03:24 | |
as he shows us how to track down some of the smallest bodies | 0:03:24 | 0:03:27 | |
in the solar system - comets and asteroids. | 0:03:27 | 0:03:30 | |
But first, Chris has been trying to image some of the other objects | 0:03:31 | 0:03:35 | |
you suggested we should look for in the night sky. | 0:03:35 | 0:03:38 | |
This building below me houses | 0:03:38 | 0:03:40 | |
one of the newer telescopes on the mountain, | 0:03:40 | 0:03:43 | |
the Liverpool Telescope, | 0:03:43 | 0:03:44 | |
and any minute now it will spring into action | 0:03:44 | 0:03:47 | |
and begin its night's observing. | 0:03:47 | 0:03:49 | |
The Liverpool Telescope has a mirror two metres across. | 0:03:53 | 0:03:56 | |
But what makes it really remarkable is that it's completely robotic, | 0:03:56 | 0:04:01 | |
and available to astronomers all over the world. | 0:04:01 | 0:04:04 | |
The nice thing about the Liverpool Telescope is that you can control it | 0:04:04 | 0:04:07 | |
from anywhere with just a web browser. | 0:04:07 | 0:04:10 | |
And so tonight, we've decided | 0:04:10 | 0:04:12 | |
we're going to look at the Waterfall Nebula. | 0:04:12 | 0:04:14 | |
It's one of the most intriguing objects in the sky. | 0:04:14 | 0:04:17 | |
It's an excellent suggestion from Lewis Ross Jones. | 0:04:17 | 0:04:20 | |
Now, the nebula is in the constellation of Orion, | 0:04:20 | 0:04:22 | |
it's just below the belt. | 0:04:22 | 0:04:24 | |
I've already put in the coordinates, | 0:04:24 | 0:04:26 | |
I've selected the filters that we're going to use | 0:04:26 | 0:04:28 | |
so that we can build up a colour picture of the object. | 0:04:28 | 0:04:31 | |
So, with all of that data here, I can click a button | 0:04:31 | 0:04:35 | |
and that object is now in the queue for tonight's observations, | 0:04:35 | 0:04:38 | |
and so at some point later on, | 0:04:38 | 0:04:39 | |
the Liverpool Telescope will swing round to Orion | 0:04:39 | 0:04:42 | |
and give us our images. | 0:04:42 | 0:04:44 | |
It really is dark out here. | 0:04:58 | 0:05:00 | |
It's one of the best skies I've ever seen. | 0:05:00 | 0:05:03 | |
When I first came outside, | 0:05:03 | 0:05:04 | |
I could see the Milky Way stretching all the way from the horizon, | 0:05:04 | 0:05:08 | |
up through Cassiopeia, overhead and then down through Orion, | 0:05:08 | 0:05:11 | |
where the Waterfall Nebula is. | 0:05:11 | 0:05:13 | |
And it's particularly clear in that part of the sky right now, | 0:05:13 | 0:05:16 | |
so I hope we're getting some excellent images. | 0:05:16 | 0:05:19 | |
Another great advantage of a robotic telescope is that | 0:05:29 | 0:05:32 | |
you don't have to stay up all night. | 0:05:32 | 0:05:34 | |
You just wait for your images to be e-mailed to you the next morning. | 0:05:34 | 0:05:39 | |
It's ten o'clock and we've now got the results from last night's run | 0:05:39 | 0:05:42 | |
on the Liverpool Telescope, | 0:05:42 | 0:05:44 | |
including our observations of the Waterfall Nebula. | 0:05:44 | 0:05:47 | |
So, let's have a look and see what we've got. | 0:05:47 | 0:05:49 | |
All of our images are here. | 0:05:49 | 0:05:51 | |
Let's start by looking at the blue image that we took. | 0:05:51 | 0:05:54 | |
In blue light, the image is pretty disappointing. | 0:05:54 | 0:05:57 | |
You can only just make out the faint outline of the nebula. | 0:05:57 | 0:06:01 | |
But when we look at the image taken with a filter | 0:06:02 | 0:06:04 | |
that lets through light from hydrogen gas, | 0:06:04 | 0:06:07 | |
we see the fine detail, and the waterfall comes to life. | 0:06:07 | 0:06:12 | |
But an individual image can't tell you too much. | 0:06:12 | 0:06:14 | |
What we have to do is put them together | 0:06:14 | 0:06:16 | |
to create a colour composite. So let's do that. | 0:06:16 | 0:06:19 | |
There we go. It's actually a beautiful image. | 0:06:19 | 0:06:22 | |
It's easy to see how the structure got its name. | 0:06:23 | 0:06:26 | |
There's even a splash of hot green gas | 0:06:26 | 0:06:28 | |
at what appears to be the bottom of the waterfall. | 0:06:28 | 0:06:32 | |
It's tempting to say there must be an object in here | 0:06:33 | 0:06:35 | |
emitting a jet, which produces this stream of material, | 0:06:35 | 0:06:40 | |
but we now know this isn't a waterfall at all, | 0:06:40 | 0:06:43 | |
this is a shock wave travelling through space in this direction. | 0:06:43 | 0:06:47 | |
To see where it comes from, we need a wider view, | 0:06:47 | 0:06:50 | |
so we've got one of those. We go here. | 0:06:50 | 0:06:53 | |
You can see, here's the waterfall, but it comes from this place here, | 0:06:53 | 0:06:57 | |
a place where there are four young hot stars | 0:06:57 | 0:07:00 | |
in orbit around each other. | 0:07:00 | 0:07:02 | |
And those stars, about 30,000 years ago, | 0:07:02 | 0:07:04 | |
had a catastrophic encounter that | 0:07:04 | 0:07:07 | |
set off the shock, which has been travelling through space ever since. | 0:07:07 | 0:07:10 | |
One of the reasons we know that is that the waterfall is here, | 0:07:10 | 0:07:14 | |
but on the opposite side there's a smaller nebula, | 0:07:14 | 0:07:16 | |
the counterpart to the waterfall, | 0:07:16 | 0:07:19 | |
that shows the other side of the shock. | 0:07:19 | 0:07:22 | |
What I really like about this story | 0:07:22 | 0:07:24 | |
is that it means this region | 0:07:24 | 0:07:26 | |
of space is changing. | 0:07:26 | 0:07:28 | |
If we came back in a few hundred years' time, the waterfall | 0:07:28 | 0:07:30 | |
will have moved and everything will look different. | 0:07:30 | 0:07:34 | |
Now, from some of the grandest objects in the night sky | 0:07:36 | 0:07:39 | |
to some of the smallest. | 0:07:39 | 0:07:41 | |
Twitter user Tony Tiger wrote in to ask if we could try and get | 0:07:41 | 0:07:44 | |
an image of a rogue asteroid. | 0:07:44 | 0:07:47 | |
A rogue asteroid is one that may in the future collide with the Earth, | 0:07:48 | 0:07:53 | |
with devastating consequences. | 0:07:53 | 0:07:56 | |
But rocky asteroids and their icy counterparts, comets, | 0:07:56 | 0:08:00 | |
are some of the hardest objects to image, because they're so small, | 0:08:00 | 0:08:04 | |
dark and they move so quickly across the sky. | 0:08:04 | 0:08:07 | |
We asked astronomer Alan Fitzsimmons | 0:08:07 | 0:08:11 | |
who's currently observing on La Palma, | 0:08:11 | 0:08:13 | |
to show us how to find these tiny but potentially deadly bodies. | 0:08:13 | 0:08:17 | |
So the important thing of course is that we need to keep the camera | 0:08:19 | 0:08:23 | |
as cold as possible. It won't take long to fill up, | 0:08:23 | 0:08:26 | |
because it was filled up this afternoon, | 0:08:26 | 0:08:27 | |
so it'll only take a couple of minutes before we get | 0:08:27 | 0:08:30 | |
the liquid nitrogen shooting back out. | 0:08:30 | 0:08:32 | |
This is the Isaac Newton Telescope. | 0:08:32 | 0:08:34 | |
It was originally built at the Royal Greenwich Observatory | 0:08:34 | 0:08:37 | |
at Herstmonceux in East Sussex in the 1960s, | 0:08:37 | 0:08:40 | |
but it was re-sited to the clear skies of La Palma in the 1980s. | 0:08:40 | 0:08:45 | |
The mirror of the Isaac Newton Telescope is 2.5 metres across. | 0:08:45 | 0:08:49 | |
That's about 100 inches in old money. | 0:08:49 | 0:08:51 | |
And it's got a field of view of half a degree across on the night sky. | 0:08:51 | 0:08:55 | |
That's about the size of the full moon. | 0:08:55 | 0:08:57 | |
That allows us to survey huge areas of sky at a single time, | 0:08:57 | 0:09:01 | |
and look for comets, asteroids and anything else we want to observe. | 0:09:01 | 0:09:05 | |
-41.3. -41.3. | 0:09:08 | 0:09:10 | |
10 plus 5. | 0:09:10 | 0:09:12 | |
-05. -18. -18. | 0:09:12 | 0:09:13 | |
-45. -45. | 0:09:13 | 0:09:15 | |
J 2000. | 0:09:15 | 0:09:17 | |
And we're on our way. | 0:09:20 | 0:09:22 | |
So when we use telescopes like this to study comets and asteroids, | 0:09:24 | 0:09:28 | |
we're not trying to see details on their surfaces. | 0:09:28 | 0:09:31 | |
We can't, they're far too small. | 0:09:31 | 0:09:33 | |
In fact, most of the time we're trying to do | 0:09:33 | 0:09:34 | |
one of a couple of things - | 0:09:34 | 0:09:36 | |
either we're trying to discover them, to find out where they are, | 0:09:36 | 0:09:40 | |
or we're trying to figure out their orbits. | 0:09:40 | 0:09:42 | |
If we get their orbits correct, | 0:09:42 | 0:09:45 | |
we can figure out where they've come from in the past, and we can also | 0:09:45 | 0:09:48 | |
hopefully figure out where they're going in the future, | 0:09:48 | 0:09:51 | |
including whether or not they're going to come near our planet. | 0:09:51 | 0:09:54 | |
-I'm getting responses now. -Good. | 0:09:54 | 0:09:57 | |
Um... Whoa, that was a bright satellite! | 0:09:57 | 0:09:59 | |
I think the Space Station's just flown over. | 0:09:59 | 0:10:02 | |
I love the Space Station. | 0:10:02 | 0:10:04 | |
When not looking at the Space Station, | 0:10:05 | 0:10:08 | |
Alan and his colleague Matthew Knight | 0:10:08 | 0:10:10 | |
will be spending the night trying to observe | 0:10:10 | 0:10:12 | |
a number of asteroids and comets, | 0:10:12 | 0:10:15 | |
and we're hoping they can fulfil our request | 0:10:15 | 0:10:17 | |
by capturing an image of one | 0:10:17 | 0:10:19 | |
that's never been observed from the Earth before. | 0:10:19 | 0:10:21 | |
Let's see. | 0:10:21 | 0:10:23 | |
323P has only been seen from space | 0:10:23 | 0:10:25 | |
by the solar observation satellite SOHO, | 0:10:25 | 0:10:29 | |
and it's unclear if it's an asteroid or a comet. | 0:10:29 | 0:10:32 | |
You can see it right here, this white dot, as it goes through. | 0:10:34 | 0:10:37 | |
And it passes through a little bit more than once every four years. | 0:10:37 | 0:10:41 | |
We're trying to study it from the ground. | 0:10:41 | 0:10:43 | |
It's never been seen from the ground before. | 0:10:43 | 0:10:45 | |
And we're trying to determine if it's a comet or if it's an asteroid, | 0:10:45 | 0:10:48 | |
because when it comes so close to the sun, | 0:10:48 | 0:10:50 | |
more or less anything would look like a comet, | 0:10:50 | 0:10:52 | |
so we're studying it here today to determine what it is. | 0:10:52 | 0:10:55 | |
From current calculations, | 0:10:57 | 0:10:59 | |
323P should be 50% further from the sun than the Earth is, | 0:10:59 | 0:11:04 | |
located somewhere around the constellations of Cancer and Gemini. | 0:11:04 | 0:11:08 | |
They're using a piece of software designed to track | 0:11:10 | 0:11:13 | |
the movement of comets and asteroids. | 0:11:13 | 0:11:15 | |
If they're searching the right part of the sky, | 0:11:15 | 0:11:18 | |
the object should leap out of the picture | 0:11:18 | 0:11:21 | |
as a single bright point of light, | 0:11:21 | 0:11:23 | |
while the stars and galaxies in the background remain blurred. | 0:11:23 | 0:11:27 | |
But after three nights observing, there's been no sign of it. | 0:11:29 | 0:11:32 | |
And time is running out. | 0:11:32 | 0:11:35 | |
-OK. Processing done. -OK, here we go, then. | 0:11:35 | 0:11:38 | |
So, we'll start from the bottom, shall we? | 0:11:38 | 0:11:40 | |
Yeah. Be methodical about it. | 0:11:40 | 0:11:41 | |
Yeah. No, I think that's noise. | 0:11:41 | 0:11:44 | |
-Yeah? -Yeah. -Yeah. | 0:11:44 | 0:11:46 | |
You see...spot anything else there? | 0:11:46 | 0:11:49 | |
-Nope. -No, neither do I. | 0:11:49 | 0:11:51 | |
-Try zooming in. -No... | 0:11:51 | 0:11:53 | |
-Doubt it. -No. -No. | 0:11:55 | 0:11:57 | |
Right. OK, so the summary is, at the moment we are still looking. | 0:11:58 | 0:12:02 | |
We have not found the comet. | 0:12:02 | 0:12:04 | |
Erm... We did a pretty deep search of that particular survey field, | 0:12:04 | 0:12:09 | |
and we're pretty sure there is nothing there. | 0:12:09 | 0:12:12 | |
But that was only half a degree across the size of the full moon. | 0:12:12 | 0:12:16 | |
We've got a few other fields still to process. | 0:12:16 | 0:12:19 | |
It could mean that it's smaller than we expected it to be, | 0:12:19 | 0:12:24 | |
it could be darker than we expected it to be, | 0:12:24 | 0:12:27 | |
so it's fainter than what we expected. | 0:12:27 | 0:12:29 | |
Or it could be that it's in another part of the sky | 0:12:29 | 0:12:33 | |
that we just haven't checked or surveyed yet. | 0:12:33 | 0:12:35 | |
So sometimes astronomy is like this. | 0:12:35 | 0:12:37 | |
Sometimes you get what you want, sometimes you don't. | 0:12:37 | 0:12:40 | |
But although 323P remains elusive, | 0:12:42 | 0:12:45 | |
as part of their night's work, Alan and Matthew were able to capture | 0:12:45 | 0:12:49 | |
an image of a rogue asteroid for us, | 0:12:49 | 0:12:52 | |
albeit one that was already well known. | 0:12:52 | 0:12:55 | |
Yeah, that's a beautiful image. | 0:12:55 | 0:12:57 | |
There's a rogue asteroid for you. | 0:12:57 | 0:13:00 | |
OK, so we were asked to image a definite asteroid. | 0:13:05 | 0:13:08 | |
In fact, a rogue asteroid, one that comes close to the Earth. | 0:13:08 | 0:13:11 | |
And so we've take these data of one called 1995CR, | 0:13:11 | 0:13:15 | |
and in these images that I'm blinking through, | 0:13:15 | 0:13:18 | |
you can see it moving against the background stars and galaxies. | 0:13:18 | 0:13:22 | |
From our brightness measurements, | 0:13:22 | 0:13:24 | |
we know that this is about 100 metres across, | 0:13:24 | 0:13:27 | |
and we also know from its orbit that it can come within | 0:13:27 | 0:13:31 | |
2 million kilometres of the Earth. | 0:13:31 | 0:13:33 | |
So, if it ever hit us, it could easily wipe out a city. | 0:13:33 | 0:13:37 | |
Now, we know we're safe from this asteroid for the next 100 years, | 0:13:37 | 0:13:41 | |
but to be sure on a longer timescale in the far future, | 0:13:41 | 0:13:44 | |
we need a better orbit, | 0:13:44 | 0:13:46 | |
so we needed to take more data for this asteroid, | 0:13:46 | 0:13:48 | |
so thanks for the request. | 0:13:48 | 0:13:51 | |
With these new observations, | 0:13:53 | 0:13:54 | |
it will be possible to refine the orbit of the asteroid | 0:13:54 | 0:13:58 | |
to find out whether it will endanger the Earth in the future. | 0:13:58 | 0:14:01 | |
You'll be sure to hear about it if it does! | 0:14:01 | 0:14:03 | |
When the Isaac Newton Telescope was built, | 0:14:07 | 0:14:09 | |
its 2.5-metre mirror made it | 0:14:09 | 0:14:11 | |
the fifth-largest telescope in the world. | 0:14:11 | 0:14:14 | |
But since then, many much larger optical telescopes have been built, | 0:14:14 | 0:14:19 | |
including the biggest of them all, the Gran Telescopio Canarias. | 0:14:19 | 0:14:24 | |
Maggie has been looking into the remarkable feats of engineering | 0:14:25 | 0:14:28 | |
that make this telescope possible, | 0:14:28 | 0:14:30 | |
and finding out what the astronomers here at using it for. | 0:14:30 | 0:14:35 | |
What we're seeing from up here | 0:14:37 | 0:14:39 | |
is the world's largest telescope mirror, | 0:14:39 | 0:14:41 | |
coming in at 10.4 metres. | 0:14:41 | 0:14:44 | |
Now, if you look carefully, you might notice | 0:14:44 | 0:14:46 | |
it's not actually a single piece of glass. | 0:14:46 | 0:14:48 | |
It's actually made up of 36 hexagonal pieces which butt up | 0:14:48 | 0:14:51 | |
against each other to make a continuous area | 0:14:51 | 0:14:54 | |
which is roughly the size of half a tennis court. | 0:14:54 | 0:14:57 | |
As it gets dark outside, | 0:14:58 | 0:15:00 | |
what the astronomers do is they prepare for a night's observation. | 0:15:00 | 0:15:03 | |
The first thing they do is open up the telescope dome, | 0:15:03 | 0:15:05 | |
and then point the telescope to the object they want to see. | 0:15:05 | 0:15:09 | |
Now, light from that object shines down onto that huge primary mirror | 0:15:09 | 0:15:13 | |
and then it gets reflected up to the secondary mirror, | 0:15:13 | 0:15:15 | |
which sits just here. You can't see it so well from here, | 0:15:15 | 0:15:18 | |
but you can see its reflection in the primary mirror. | 0:15:18 | 0:15:21 | |
Now, light is then focused down into that tube in the centre. | 0:15:21 | 0:15:25 | |
That tube actually directs light to the instruments that sit either side | 0:15:25 | 0:15:28 | |
of the main mirror. | 0:15:28 | 0:15:30 | |
It's an amazing piece of engineering. | 0:15:30 | 0:15:32 | |
To enable it to point anywhere in the sky, the whole telescope, | 0:15:36 | 0:15:40 | |
all 400 tonnes of it, is mounted on a moving platform. | 0:15:40 | 0:15:44 | |
I think it's amazing. The biggest telescope in the world, | 0:15:46 | 0:15:49 | |
and what always surprises me is how smooth they run. | 0:15:49 | 0:15:52 | |
You just don't feel any vibrations, nothing. It just glides. | 0:15:52 | 0:15:56 | |
What I find fascinating about telescopes like these is, | 0:15:57 | 0:16:01 | |
for all their huge mirrors and complicated optics, | 0:16:01 | 0:16:04 | |
they're not much better in terms of magnification | 0:16:04 | 0:16:06 | |
than your best amateur telescopes, | 0:16:06 | 0:16:08 | |
but where they do gain is in terms of light-gathering power, | 0:16:08 | 0:16:12 | |
because when you've got a mirror that big, | 0:16:12 | 0:16:14 | |
you can see faint distant objects so, so much more clearly. | 0:16:14 | 0:16:17 | |
The GTC is so sensitive it could detect a light from a single candle | 0:16:21 | 0:16:26 | |
as far away as Mars. | 0:16:26 | 0:16:29 | |
But what the telescope is really used for | 0:16:31 | 0:16:33 | |
is looking deep into space... | 0:16:33 | 0:16:35 | |
..to see objects that, although intrinsically very bright, | 0:16:37 | 0:16:41 | |
are extremely far away. | 0:16:41 | 0:16:43 | |
GranTeCan has kindly agreed | 0:16:47 | 0:16:49 | |
to devote some of their valuable viewing time | 0:16:49 | 0:16:52 | |
to capture an image especially for us. | 0:16:52 | 0:16:55 | |
Many of you, Angela Southwood, Mark Williams and George Brown, | 0:16:55 | 0:17:00 | |
to name but three, wrote in to ask that we image galaxies. | 0:17:00 | 0:17:05 | |
Many were suggested but we had to choose just one. | 0:17:05 | 0:17:09 | |
And so the giant telescope homed in on NGC891, | 0:17:11 | 0:17:16 | |
a galaxy much like the Milky Way, | 0:17:16 | 0:17:18 | |
30 million light years from Earth. | 0:17:18 | 0:17:22 | |
So, the telescope is now pointing? | 0:17:22 | 0:17:24 | |
We're now right there. | 0:17:24 | 0:17:26 | |
So, are we actually getting an exposure as we speak? | 0:17:26 | 0:17:29 | |
It's reading out. | 0:17:29 | 0:17:30 | |
OK, so you've got the exposure. | 0:17:30 | 0:17:32 | |
-Yes. -In a few seconds, we're going to see the very first image. | 0:17:32 | 0:17:35 | |
It will appear. | 0:17:35 | 0:17:36 | |
It's beautiful! | 0:17:42 | 0:17:44 | |
At a mere 30 million light years away, | 0:17:45 | 0:17:48 | |
the galaxy is too big for GranTeCan to image in a single frame. | 0:17:48 | 0:17:52 | |
And it takes a range of exposures at different wavelengths of light. | 0:17:53 | 0:17:57 | |
Stefan, can you tell me, what are you seeing here? | 0:17:59 | 0:18:02 | |
So, basically, spiral galaxies are like various plain discs. | 0:18:02 | 0:18:05 | |
For example, our Milky Way has an extension of 100,000 light years, | 0:18:05 | 0:18:11 | |
that's pretty big, but it's only a few thousand light years thick. | 0:18:11 | 0:18:15 | |
So, it basically has the form of a Frisbee, or a pizza, | 0:18:15 | 0:18:19 | |
or whatever you like. | 0:18:19 | 0:18:21 | |
And the particular thing about this galaxy is that we are looking at it | 0:18:21 | 0:18:24 | |
right from the side. | 0:18:24 | 0:18:26 | |
All the light you see here comes from many billions of stars. | 0:18:26 | 0:18:30 | |
-That make up the galaxy. -A galaxy like this consists of | 0:18:30 | 0:18:34 | |
at least 100 billion stars. | 0:18:34 | 0:18:37 | |
-Similar to our own. -So, we do not see any single star in that galaxy. | 0:18:37 | 0:18:41 | |
At fast first glance, you may think that there are no stars, | 0:18:41 | 0:18:45 | |
where you see the black stripes, | 0:18:45 | 0:18:47 | |
but there are as many stars | 0:18:47 | 0:18:49 | |
as in all the other regions, | 0:18:49 | 0:18:51 | |
it's just that the light is blocked by the dust in the foreground. | 0:18:51 | 0:18:56 | |
Those are the details we can make out on the first view, | 0:18:56 | 0:19:00 | |
but to get the best image of the galaxy, | 0:19:00 | 0:19:02 | |
we needed to process all the images we took that night | 0:19:02 | 0:19:06 | |
into a single composite. | 0:19:06 | 0:19:08 | |
This is the finished image. | 0:19:10 | 0:19:13 | |
A stunning view of galaxy NGC891, | 0:19:15 | 0:19:18 | |
taken by the Gran Telescopio Canarias. | 0:19:18 | 0:19:22 | |
Now, not everything that you requested we look at | 0:19:29 | 0:19:32 | |
requires a huge professional telescope. | 0:19:32 | 0:19:34 | |
One of the most popular suggestions we had was to look at the moon, | 0:19:34 | 0:19:38 | |
and to see if we could see evidence of the Apollo landings | 0:19:38 | 0:19:41 | |
on its surface. | 0:19:41 | 0:19:42 | |
So, we sent Pete out with his telescope to see what he could find. | 0:19:42 | 0:19:46 | |
'Both men stand about the fourth rung up...' | 0:19:46 | 0:19:48 | |
The Apollo missions captured the world's imagination | 0:19:48 | 0:19:51 | |
from 1969 to 1972, | 0:19:51 | 0:19:55 | |
when a total of 12 astronauts walked on the moon, | 0:19:55 | 0:19:58 | |
and what remains of their equipment is still up there. | 0:19:58 | 0:20:02 | |
The question is, can we see it? | 0:20:02 | 0:20:04 | |
The first successful landing was Apollo 11, | 0:20:04 | 0:20:08 | |
which set down in the now-famous Sea of Tranquillity, | 0:20:08 | 0:20:11 | |
and that's going to be my first target this evening. | 0:20:11 | 0:20:14 | |
With a three-inch telescope, | 0:20:15 | 0:20:17 | |
you should be able to get a good view of the moon's surface. | 0:20:17 | 0:20:21 | |
The Sea of Tranquillity is located just north and slightly east of the | 0:20:22 | 0:20:27 | |
centre of the moon, it's this dark patch here. | 0:20:27 | 0:20:30 | |
Now, the Apollo 11 landing site | 0:20:30 | 0:20:32 | |
is located in a region just to the south | 0:20:32 | 0:20:36 | |
of that dark patch. | 0:20:36 | 0:20:37 | |
A great challenge is to try and find the three small craters which are | 0:20:37 | 0:20:42 | |
located just in the north of the landing site. | 0:20:42 | 0:20:44 | |
These are named after the Apollo 11 astronauts - | 0:20:44 | 0:20:47 | |
Armstrong, Aldrin and Collins. | 0:20:47 | 0:20:49 | |
To find them, locate the nearest noticeable crater, | 0:20:51 | 0:20:55 | |
7km-diameter Moltke, | 0:20:55 | 0:20:57 | |
and look north to locate the three craters. | 0:20:57 | 0:21:00 | |
As the largest is just 4.6km across, | 0:21:01 | 0:21:04 | |
they can be difficult to spot, | 0:21:04 | 0:21:07 | |
requiring at least an eight-inch scope and steady conditions. | 0:21:07 | 0:21:10 | |
Unfortunately, you won't be able to see any remnants | 0:21:11 | 0:21:14 | |
of the Apollo landing sites. In fact, | 0:21:14 | 0:21:16 | |
it's impossible to see them with any ground-based telescope at all. | 0:21:16 | 0:21:20 | |
'One. Ignition. | 0:21:23 | 0:21:25 | |
-'We're on our way, Houston! -Rates are good.' | 0:21:25 | 0:21:30 | |
The largest piece of equipment left behind after each mission | 0:21:30 | 0:21:33 | |
was the descent stage of the lunar module. | 0:21:33 | 0:21:37 | |
At a measly 4.2 metres wide and 3.2 metres high, | 0:21:37 | 0:21:41 | |
not even the Hubble Space Telescope | 0:21:41 | 0:21:43 | |
has the optical resolution to see it. | 0:21:43 | 0:21:46 | |
But although we can't see the remains of the lunar missions | 0:21:51 | 0:21:54 | |
from the ground, it has been possible to image them | 0:21:54 | 0:21:56 | |
using spacecraft orbiting the moon. | 0:21:56 | 0:21:59 | |
The Lunar Reconnaissance Orbiter, which was launched in 2009, | 0:21:59 | 0:22:03 | |
has imaged the lunar surface in unprecedented detail, | 0:22:03 | 0:22:07 | |
and uncovered some of the relics | 0:22:07 | 0:22:09 | |
left behind by the Apollo 11 mission. | 0:22:09 | 0:22:11 | |
In this image, you can clearly see the lunar module, | 0:22:11 | 0:22:14 | |
and you can even see some of the tracks which have been left behind | 0:22:14 | 0:22:17 | |
on the moon's surface by Armstrong and Aldrin | 0:22:17 | 0:22:19 | |
as they have explored the site. | 0:22:19 | 0:22:22 | |
And the LRO spacecraft has also rediscovered the landing sites | 0:22:24 | 0:22:27 | |
of the other Apollo missions. | 0:22:27 | 0:22:30 | |
In 1971, | 0:22:30 | 0:22:32 | |
Apollo 15 astronauts James Irwin and David Scott | 0:22:32 | 0:22:36 | |
were the first to drive the lunar rover, | 0:22:36 | 0:22:38 | |
and judging by the 17 miles of tyre tracks left behind, | 0:22:38 | 0:22:42 | |
they clearly took it for a good spin. | 0:22:42 | 0:22:45 | |
Interestingly, the pictures taken by the crews on the moon do reveal | 0:22:45 | 0:22:49 | |
aspects of the landing sites we can see from Earth, | 0:22:49 | 0:22:53 | |
and that's because the pictures show features of lunar geology. | 0:22:53 | 0:22:58 | |
Behind this picture of the Apollo 15 lander, | 0:23:00 | 0:23:02 | |
you can clearly see a lunar mountain, part of the Appennines, | 0:23:02 | 0:23:07 | |
a mountain range you can see from the Earth | 0:23:07 | 0:23:10 | |
even with a pair of binoculars. | 0:23:10 | 0:23:12 | |
The closest large crater to the landing site | 0:23:12 | 0:23:14 | |
is Archimedes, which is north of the moon's centre. | 0:23:14 | 0:23:18 | |
The Appennines are the bright strip | 0:23:18 | 0:23:20 | |
running beside it. | 0:23:20 | 0:23:22 | |
Locate the part of the range | 0:23:22 | 0:23:24 | |
closest to Archimedes | 0:23:24 | 0:23:26 | |
to find the sinuous Hadley Rille, | 0:23:26 | 0:23:28 | |
near to where Apollo 15 landed. | 0:23:28 | 0:23:31 | |
The moon will be good for observing over the next week or so, | 0:23:31 | 0:23:34 | |
so if you fancy having a go | 0:23:34 | 0:23:36 | |
at trying to find the landing areas yourself, | 0:23:36 | 0:23:38 | |
then you can find more information on our website. | 0:23:38 | 0:23:42 | |
Before we reach the end of the show, | 0:23:47 | 0:23:49 | |
there's one other popular request we should deal with. | 0:23:49 | 0:23:53 | |
Daniel King and Jason Brighton, amongst others, wanted us to take | 0:23:53 | 0:23:56 | |
a picture of an exoplanet orbiting another star. | 0:23:56 | 0:23:59 | |
Now, that's no easy task, | 0:23:59 | 0:24:01 | |
but several of the telescopes here on La Palma | 0:24:01 | 0:24:03 | |
do spend their time trying to discover exoplanets. | 0:24:03 | 0:24:06 | |
The most prolific planet-hunter on the island doesn't look like much. | 0:24:14 | 0:24:17 | |
This unprepossessing shed houses SuperWASP, which is capable of | 0:24:17 | 0:24:22 | |
monitoring the brightness of 800,000 stars at once, | 0:24:22 | 0:24:26 | |
looking for the tiny dips in brightness | 0:24:26 | 0:24:28 | |
which tell us that a planet has passed between us and the star. | 0:24:28 | 0:24:33 | |
Between this installation and a replica in South Africa, | 0:24:33 | 0:24:36 | |
SuperWASP has discovered more than 100 extrasolar planets. | 0:24:36 | 0:24:40 | |
But tonight, we're not going to be using SuperWASP. | 0:24:46 | 0:24:49 | |
We're going to be looking at another planet-hunting project | 0:24:49 | 0:24:53 | |
hosted in the Italian Galileo Telescope. | 0:24:53 | 0:24:56 | |
Wow! Look at this. | 0:25:00 | 0:25:02 | |
This is the telescope Nazionale Galileo. | 0:25:02 | 0:25:06 | |
I think Galileo would have been pleased with it. | 0:25:06 | 0:25:08 | |
It looks enormous. | 0:25:08 | 0:25:10 | |
It's even more impressive because of the closeness of these walls. | 0:25:10 | 0:25:13 | |
If you have a look, | 0:25:13 | 0:25:15 | |
the really exciting thing about this telescope is the mirror. | 0:25:15 | 0:25:18 | |
If you come over here, this is the primary mirror, | 0:25:18 | 0:25:20 | |
nearly four metres across. But look how thin it is. | 0:25:20 | 0:25:23 | |
That thinness means it can flex to account for | 0:25:23 | 0:25:26 | |
the movement of the atmosphere. It's called active optics, | 0:25:26 | 0:25:29 | |
and it's the secret to why this is an excellent planet-hunting machine. | 0:25:29 | 0:25:34 | |
It's hard to detect an exoplanet directly | 0:25:39 | 0:25:42 | |
because the glare of the light | 0:25:42 | 0:25:44 | |
from its neighbouring star is just too dazzling. | 0:25:44 | 0:25:46 | |
So what we have to do instead | 0:25:46 | 0:25:48 | |
is find indirect ways of telling that the planet's there. | 0:25:48 | 0:25:51 | |
If you think about a planet in orbit around its star, | 0:25:51 | 0:25:54 | |
then the planet's gravity must be pulling on that star, | 0:25:54 | 0:25:57 | |
and the star will wobble back and forth as the planet orbits it. | 0:25:57 | 0:26:01 | |
And so what we need is a way to tell if the star is wobbling, | 0:26:01 | 0:26:04 | |
and that's what HARP does. | 0:26:04 | 0:26:06 | |
It does that by looking at the spectrum of the star, | 0:26:06 | 0:26:09 | |
and we can see what will happen if we look at a spectrum of the sun. | 0:26:09 | 0:26:12 | |
So, you get the familiar rainbow pattern. | 0:26:12 | 0:26:15 | |
But you also get these dark lines. | 0:26:15 | 0:26:17 | |
And the lines mark the presence of particular elements. | 0:26:17 | 0:26:20 | |
Now, the pattern of lines remains constant, | 0:26:22 | 0:26:25 | |
but the whole spectrum shifts as the star moves. | 0:26:25 | 0:26:28 | |
The spectrum becomes more red when the star is moving away from us, | 0:26:28 | 0:26:32 | |
and more blue when it moves towards us. | 0:26:32 | 0:26:34 | |
And it's that red-blue, red-blue pattern | 0:26:34 | 0:26:37 | |
that indicates the presence of a planet around a star. | 0:26:37 | 0:26:41 | |
And that is what the team here are hoping to find. | 0:26:41 | 0:26:44 | |
In the control room, | 0:26:46 | 0:26:48 | |
the Italian team train the telescope on individual stars, | 0:26:48 | 0:26:52 | |
and take their spectra. | 0:26:52 | 0:26:54 | |
The HARPS instrument is so sensitive that it can detect if the star is | 0:26:54 | 0:26:58 | |
moving towards or away from us | 0:26:58 | 0:27:00 | |
at speeds as low as one metre per second. | 0:27:00 | 0:27:03 | |
That's walking pace. | 0:27:03 | 0:27:05 | |
But one spectrum isn't enough to reveal the presence of a planet. | 0:27:06 | 0:27:11 | |
The same star must be observed, | 0:27:11 | 0:27:13 | |
and its rate of motion measured again and again over many nights. | 0:27:13 | 0:27:18 | |
These are results from a star in the Beehive Cluster | 0:27:19 | 0:27:22 | |
that was observed many times between 2013 and 2015. | 0:27:22 | 0:27:27 | |
So, that's it. After all that work, | 0:27:29 | 0:27:31 | |
70 nights of observation over two years, we're left with a graph. | 0:27:31 | 0:27:35 | |
But it's a good graph. You can see from the way the star moves, | 0:27:35 | 0:27:38 | |
this back and forth, | 0:27:38 | 0:27:40 | |
it's this pattern that tells us there's a planet there. | 0:27:40 | 0:27:43 | |
And so we can't get you an image of an exoplanet, I'm afraid, | 0:27:43 | 0:27:46 | |
but I'm telling you, this is just as good. | 0:27:46 | 0:27:49 | |
That's all we've got time for this month. | 0:28:01 | 0:28:03 | |
And next month, there's no show. | 0:28:03 | 0:28:05 | |
But you can still get your astronomical fix | 0:28:05 | 0:28:07 | |
by watching Stargazing Live on BBC Two from 28th March. | 0:28:07 | 0:28:11 | |
We'll be back in April to celebrate a very special anniversary - | 0:28:11 | 0:28:14 | |
The Sky At Night's 60th birthday. | 0:28:14 | 0:28:17 | |
Until then, get outside, get looking up. | 0:28:17 | 0:28:20 | |
Good night. | 0:28:20 | 0:28:22 |