Telescope Takeover The Sky at Night

This month, we've come to the Roque de los Muchachos Observatory

on the island of La Palma, in the Canary Islands.

It's home to the largest collection of major telescopes

anywhere in Europe, including this magnificent machine,

the Gran Telescopio Canarias,

the largest steerable optical telescope anywhere in the world.

Over the next few nights,

we'll be putting some of these telescopes through their paces,

as we take a voyage of discovery out through the galaxy and beyond.

A voyage chartered by you.

Last month, we invited you to suggest the objects in the night sky

that you would like to have a much closer look at.

You sent us loads of suggestions.

And we've chosen some of the best

to be imaged by these powerful instruments.

Tonight, we're taking over the telescopes of La Palma.

Welcome to The Sky At Night.

It's amazing. We are actually above the clouds.

When people think of La Palma, they think of sun, sand and sea.

But up here it's quite different.

This site sits 2,400 metres above sea level, on a dormant volcano,

and it's quite cold.

But there's a big compensation.

Viewing conditions up here are amongst the best in the world,

and with virtually no light pollution

and up to 300 clear nights a year,

it's a great place to do observing.

Because of these exceptional conditions,

countries from all over Europe have built telescopes here.

There are over 30 of them on the mountain,

all designed to probe the secrets of the universe in different ways.

The telescope behind is called MAGIC,

and it's designed to look for gamma ray bursts in distant galaxies.

And up there on the hill is the Swedish solar telescope,

which is looking at our local star, the sun.

And dotted across the hillsides,

these large domes contain huge instruments

which can look deep into the universe.

These are the telescopes we'll be using to view your suggestions.

We'll be looking at distant galaxies using the vast GTC,

known to astronomers as GranTeCan.

We'll be joining the hunt for exoplanets around other stars.

And we'll be following Alan Fitzsimmons,

as he shows us how to track down some of the smallest bodies

in the solar system - comets and asteroids.

But first, Chris has been trying to image some of the other objects

you suggested we should look for in the night sky.

This building below me houses

one of the newer telescopes on the mountain,

the Liverpool Telescope,

and any minute now it will spring into action

and begin its night's observing.

The Liverpool Telescope has a mirror two metres across.

But what makes it really remarkable is that it's completely robotic,

and available to astronomers all over the world.

The nice thing about the Liverpool Telescope is that you can control it

from anywhere with just a web browser.

And so tonight, we've decided

we're going to look at the Waterfall Nebula.

It's one of the most intriguing objects in the sky.

It's an excellent suggestion from Lewis Ross Jones.

Now, the nebula is in the constellation of Orion,

it's just below the belt.

I've already put in the coordinates,

I've selected the filters that we're going to use

so that we can build up a colour picture of the object.

So, with all of that data here, I can click a button

and that object is now in the queue for tonight's observations,

and so at some point later on,

the Liverpool Telescope will swing round to Orion

and give us our images.

It really is dark out here.

It's one of the best skies I've ever seen.

When I first came outside,

I could see the Milky Way stretching all the way from the horizon,

up through Cassiopeia, overhead and then down through Orion,

where the Waterfall Nebula is.

And it's particularly clear in that part of the sky right now,

so I hope we're getting some excellent images.

Another great advantage of a robotic telescope is that

you don't have to stay up all night.

You just wait for your images to be e-mailed to you the next morning.

It's ten o'clock and we've now got the results from last night's run

on the Liverpool Telescope,

including our observations of the Waterfall Nebula.

So, let's have a look and see what we've got.

All of our images are here.

Let's start by looking at the blue image that we took.

In blue light, the image is pretty disappointing.

You can only just make out the faint outline of the nebula.

But when we look at the image taken with a filter

that lets through light from hydrogen gas,

we see the fine detail, and the waterfall comes to life.

But an individual image can't tell you too much.

What we have to do is put them together

to create a colour composite. So let's do that.

There we go. It's actually a beautiful image.

It's easy to see how the structure got its name.

There's even a splash of hot green gas

at what appears to be the bottom of the waterfall.

It's tempting to say there must be an object in here

emitting a jet, which produces this stream of material,

but we now know this isn't a waterfall at all,

this is a shock wave travelling through space in this direction.

To see where it comes from, we need a wider view,

so we've got one of those. We go here.

You can see, here's the waterfall, but it comes from this place here,

a place where there are four young hot stars

in orbit around each other.

And those stars, about 30,000 years ago,

had a catastrophic encounter that

set off the shock, which has been travelling through space ever since.

One of the reasons we know that is that the waterfall is here,

but on the opposite side there's a smaller nebula,

the counterpart to the waterfall,

that shows the other side of the shock.

What I really like about this story

is that it means this region

of space is changing.

If we came back in a few hundred years' time, the waterfall

will have moved and everything will look different.

Now, from some of the grandest objects in the night sky

to some of the smallest.

Twitter user Tony Tiger wrote in to ask if we could try and get

an image of a rogue asteroid.

A rogue asteroid is one that may in the future collide with the Earth,

with devastating consequences.

But rocky asteroids and their icy counterparts, comets,

are some of the hardest objects to image, because they're so small,

dark and they move so quickly across the sky.

We asked astronomer Alan Fitzsimmons

who's currently observing on La Palma,

to show us how to find these tiny but potentially deadly bodies.

So the important thing of course is that we need to keep the camera

as cold as possible. It won't take long to fill up,

because it was filled up this afternoon,

so it'll only take a couple of minutes before we get

the liquid nitrogen shooting back out.

This is the Isaac Newton Telescope.

It was originally built at the Royal Greenwich Observatory

at Herstmonceux in East Sussex in the 1960s,

but it was re-sited to the clear skies of La Palma in the 1980s.

The mirror of the Isaac Newton Telescope is 2.5 metres across.

That's about 100 inches in old money.

And it's got a field of view of half a degree across on the night sky.

That's about the size of the full moon.

That allows us to survey huge areas of sky at a single time,

and look for comets, asteroids and anything else we want to observe.

-41.3.

-41.3.

10 plus 5.

-05.

-18.

-18.

-45.

-45.

J 2000.

And we're on our way.

So when we use telescopes like this to study comets and asteroids,

we're not trying to see details on their surfaces.

We can't, they're far too small.

In fact, most of the time we're trying to do

one of a couple of things -

either we're trying to discover them, to find out where they are,

or we're trying to figure out their orbits.

If we get their orbits correct,

we can figure out where they've come from in the past, and we can also

hopefully figure out where they're going in the future,

including whether or not they're going to come near our planet.

-I'm getting responses now.

-Good.

Um... Whoa, that was a bright satellite!

I think the Space Station's just flown over.

I love the Space Station.

When not looking at the Space Station,

Alan and his colleague Matthew Knight

will be spending the night trying to observe

a number of asteroids and comets,

and we're hoping they can fulfil our request

by capturing an image of one

that's never been observed from the Earth before.

Let's see.

323P has only been seen from space

by the solar observation satellite SOHO,

and it's unclear if it's an asteroid or a comet.

You can see it right here, this white dot, as it goes through.

And it passes through a little bit more than once every four years.

We're trying to study it from the ground.

It's never been seen from the ground before.

And we're trying to determine if it's a comet or if it's an asteroid,

because when it comes so close to the sun,

more or less anything would look like a comet,

so we're studying it here today to determine what it is.

From current calculations,

323P should be 50% further from the sun than the Earth is,

located somewhere around the constellations of Cancer and Gemini.

They're using a piece of software designed to track

the movement of comets and asteroids.

If they're searching the right part of the sky,

the object should leap out of the picture

as a single bright point of light,

while the stars and galaxies in the background remain blurred.

But after three nights observing, there's been no sign of it.

And time is running out.

-OK. Processing done.

-OK, here we go, then.

So, we'll start from the bottom, shall we?

Yeah. Be methodical about it.

Yeah. No, I think that's noise.

-Yeah?

-Yeah.

-Yeah.

You see...spot anything else there?

-Nope.

-No, neither do I.

-Try zooming in.

-No...

-Doubt it.

-No.

-No.

Right. OK, so the summary is, at the moment we are still looking.

We have not found the comet.

Erm... We did a pretty deep search of that particular survey field,

and we're pretty sure there is nothing there.

But that was only half a degree across the size of the full moon.

We've got a few other fields still to process.

It could mean that it's smaller than we expected it to be,

it could be darker than we expected it to be,

so it's fainter than what we expected.

Or it could be that it's in another part of the sky

that we just haven't checked or surveyed yet.

So sometimes astronomy is like this.

Sometimes you get what you want, sometimes you don't.

But although 323P remains elusive,

as part of their night's work, Alan and Matthew were able to capture

an image of a rogue asteroid for us,

albeit one that was already well known.

Yeah, that's a beautiful image.

There's a rogue asteroid for you.

OK, so we were asked to image a definite asteroid.

In fact, a rogue asteroid, one that comes close to the Earth.

And so we've take these data of one called 1995CR,

and in these images that I'm blinking through,

you can see it moving against the background stars and galaxies.

From our brightness measurements,

we know that this is about 100 metres across,

and we also know from its orbit that it can come within

2 million kilometres of the Earth.

So, if it ever hit us, it could easily wipe out a city.

Now, we know we're safe from this asteroid for the next 100 years,

but to be sure on a longer timescale in the far future,

we need a better orbit,

so we needed to take more data for this asteroid,

so thanks for the request.

With these new observations,

it will be possible to refine the orbit of the asteroid

to find out whether it will endanger the Earth in the future.

You'll be sure to hear about it if it does!

When the Isaac Newton Telescope was built,

its 2.5-metre mirror made it

the fifth-largest telescope in the world.

But since then, many much larger optical telescopes have been built,

including the biggest of them all, the Gran Telescopio Canarias.

Maggie has been looking into the remarkable feats of engineering

that make this telescope possible,

and finding out what the astronomers here at using it for.

What we're seeing from up here

is the world's largest telescope mirror,

coming in at 10.4 metres.

Now, if you look carefully, you might notice

it's not actually a single piece of glass.

It's actually made up of 36 hexagonal pieces which butt up

against each other to make a continuous area

which is roughly the size of half a tennis court.

As it gets dark outside,

what the astronomers do is they prepare for a night's observation.

The first thing they do is open up the telescope dome,

and then point the telescope to the object they want to see.

Now, light from that object shines down onto that huge primary mirror

and then it gets reflected up to the secondary mirror,

which sits just here. You can't see it so well from here,

but you can see its reflection in the primary mirror.

Now, light is then focused down into that tube in the centre.

That tube actually directs light to the instruments that sit either side

of the main mirror.

It's an amazing piece of engineering.

To enable it to point anywhere in the sky, the whole telescope,

all 400 tonnes of it, is mounted on a moving platform.

I think it's amazing. The biggest telescope in the world,

and what always surprises me is how smooth they run.

You just don't feel any vibrations, nothing. It just glides.

What I find fascinating about telescopes like these is,

for all their huge mirrors and complicated optics,

they're not much better in terms of magnification

than your best amateur telescopes,

but where they do gain is in terms of light-gathering power,

because when you've got a mirror that big,

you can see faint distant objects so, so much more clearly.

The GTC is so sensitive it could detect a light from a single candle

as far away as Mars.

But what the telescope is really used for

is looking deep into space...

..to see objects that, although intrinsically very bright,

are extremely far away.

GranTeCan has kindly agreed

to devote some of their valuable viewing time

to capture an image especially for us.

Many of you, Angela Southwood, Mark Williams and George Brown,

to name but three, wrote in to ask that we image galaxies.

Many were suggested but we had to choose just one.

And so the giant telescope homed in on NGC891,

a galaxy much like the Milky Way,

30 million light years from Earth.

So, the telescope is now pointing?

We're now right there.

So, are we actually getting an exposure as we speak?

It's reading out.

OK, so you've got the exposure.

-Yes.

-In a few seconds, we're going to see the very first image.

It will appear.

It's beautiful!

At a mere 30 million light years away,

the galaxy is too big for GranTeCan to image in a single frame.

And it takes a range of exposures at different wavelengths of light.

Stefan, can you tell me, what are you seeing here?

So, basically, spiral galaxies are like various plain discs.

For example, our Milky Way has an extension of 100,000 light years,

that's pretty big, but it's only a few thousand light years thick.

So, it basically has the form of a Frisbee, or a pizza,

or whatever you like.

And the particular thing about this galaxy is that we are looking at it

right from the side.

All the light you see here comes from many billions of stars.

-That make up the galaxy.

-A galaxy like this consists of

at least 100 billion stars.

-Similar to our own.

-So, we do not see any single star in that galaxy.

At fast first glance, you may think that there are no stars,

where you see the black stripes,

but there are as many stars

as in all the other regions,

it's just that the light is blocked by the dust in the foreground.

Those are the details we can make out on the first view,

but to get the best image of the galaxy,

we needed to process all the images we took that night

into a single composite.

This is the finished image.

A stunning view of galaxy NGC891,

taken by the Gran Telescopio Canarias.

Now, not everything that you requested we look at

requires a huge professional telescope.

One of the most popular suggestions we had was to look at the moon,

and to see if we could see evidence of the Apollo landings

on its surface.

So, we sent Pete out with his telescope to see what he could find.

'Both men stand about the fourth rung up...'

The Apollo missions captured the world's imagination

from 1969 to 1972,

when a total of 12 astronauts walked on the moon,

and what remains of their equipment is still up there.

The question is, can we see it?

The first successful landing was Apollo 11,

which set down in the now-famous Sea of Tranquillity,

and that's going to be my first target this evening.

With a three-inch telescope,

you should be able to get a good view of the moon's surface.

The Sea of Tranquillity is located just north and slightly east of the

centre of the moon, it's this dark patch here.

Now, the Apollo 11 landing site

is located in a region just to the south

of that dark patch.

A great challenge is to try and find the three small craters which are

located just in the north of the landing site.

These are named after the Apollo 11 astronauts -

Armstrong, Aldrin and Collins.

To find them, locate the nearest noticeable crater,

7km-diameter Moltke,

and look north to locate the three craters.

As the largest is just 4.6km across,

they can be difficult to spot,

requiring at least an eight-inch scope and steady conditions.

Unfortunately, you won't be able to see any remnants

of the Apollo landing sites. In fact,

it's impossible to see them with any ground-based telescope at all.

'One. Ignition.

-'We're on our way, Houston!

-Rates are good.'

The largest piece of equipment left behind after each mission

was the descent stage of the lunar module.

At a measly 4.2 metres wide and 3.2 metres high,

not even the Hubble Space Telescope

has the optical resolution to see it.

But although we can't see the remains of the lunar missions

from the ground, it has been possible to image them

using spacecraft orbiting the moon.

The Lunar Reconnaissance Orbiter, which was launched in 2009,

has imaged the lunar surface in unprecedented detail,

and uncovered some of the relics

left behind by the Apollo 11 mission.

In this image, you can clearly see the lunar module,

and you can even see some of the tracks which have been left behind

on the moon's surface by Armstrong and Aldrin

as they have explored the site.

And the LRO spacecraft has also rediscovered the landing sites

of the other Apollo missions.

In 1971,

Apollo 15 astronauts James Irwin and David Scott

were the first to drive the lunar rover,

and judging by the 17 miles of tyre tracks left behind,

they clearly took it for a good spin.

Interestingly, the pictures taken by the crews on the moon do reveal

aspects of the landing sites we can see from Earth,

and that's because the pictures show features of lunar geology.

Behind this picture of the Apollo 15 lander,

you can clearly see a lunar mountain, part of the Appennines,

a mountain range you can see from the Earth

even with a pair of binoculars.

The closest large crater to the landing site

is Archimedes, which is north of the moon's centre.

The Appennines are the bright strip

running beside it.

Locate the part of the range

closest to Archimedes

to find the sinuous Hadley Rille,

near to where Apollo 15 landed.

The moon will be good for observing over the next week or so,

so if you fancy having a go

at trying to find the landing areas yourself,

then you can find more information on our website.

Before we reach the end of the show,

there's one other popular request we should deal with.

Daniel King and Jason Brighton, amongst others, wanted us to take

a picture of an exoplanet orbiting another star.

Now, that's no easy task,

but several of the telescopes here on La Palma

do spend their time trying to discover exoplanets.

The most prolific planet-hunter on the island doesn't look like much.

This unprepossessing shed houses SuperWASP, which is capable of

monitoring the brightness of 800,000 stars at once,

looking for the tiny dips in brightness

which tell us that a planet has passed between us and the star.

Between this installation and a replica in South Africa,

SuperWASP has discovered more than 100 extrasolar planets.

But tonight, we're not going to be using SuperWASP.

We're going to be looking at another planet-hunting project

hosted in the Italian Galileo Telescope.

Wow! Look at this.

This is the telescope Nazionale Galileo.

I think Galileo would have been pleased with it.

It looks enormous.

It's even more impressive because of the closeness of these walls.

If you have a look,

the really exciting thing about this telescope is the mirror.

If you come over here, this is the primary mirror,

nearly four metres across. But look how thin it is.

That thinness means it can flex to account for

the movement of the atmosphere. It's called active optics,

and it's the secret to why this is an excellent planet-hunting machine.

It's hard to detect an exoplanet directly

because the glare of the light

from its neighbouring star is just too dazzling.

So what we have to do instead

is find indirect ways of telling that the planet's there.

If you think about a planet in orbit around its star,

then the planet's gravity must be pulling on that star,

and the star will wobble back and forth as the planet orbits it.

And so what we need is a way to tell if the star is wobbling,

and that's what HARP does.

It does that by looking at the spectrum of the star,

and we can see what will happen if we look at a spectrum of the sun.

So, you get the familiar rainbow pattern.

But you also get these dark lines.

And the lines mark the presence of particular elements.

Now, the pattern of lines remains constant,

but the whole spectrum shifts as the star moves.

The spectrum becomes more red when the star is moving away from us,

and more blue when it moves towards us.

And it's that red-blue, red-blue pattern

that indicates the presence of a planet around a star.

And that is what the team here are hoping to find.

In the control room,

the Italian team train the telescope on individual stars,

and take their spectra.

The HARPS instrument is so sensitive that it can detect if the star is

moving towards or away from us

at speeds as low as one metre per second.

That's walking pace.

But one spectrum isn't enough to reveal the presence of a planet.

The same star must be observed,

and its rate of motion measured again and again over many nights.

These are results from a star in the Beehive Cluster

that was observed many times between 2013 and 2015.

So, that's it. After all that work,

70 nights of observation over two years, we're left with a graph.

But it's a good graph. You can see from the way the star moves,

this back and forth,

it's this pattern that tells us there's a planet there.

And so we can't get you an image of an exoplanet, I'm afraid,

but I'm telling you, this is just as good.

That's all we've got time for this month.

And next month, there's no show.

But you can still get your astronomical fix

by watching Stargazing Live on BBC Two from 28th March.

We'll be back in April to celebrate a very special anniversary -

The Sky At Night's 60th birthday.

Until then, get outside, get looking up.

Good night.