0:00:27 > 0:00:28Good evening.
0:00:28 > 0:00:33On this programme, we're going to talk about far-infrared astronomy
0:00:33 > 0:00:36and some people won't know what that means.
0:00:36 > 0:00:38What is far infrared?
0:00:38 > 0:00:41Well, here we have three experts -
0:00:41 > 0:00:44Chris Lintott, Chris North and John Richer.
0:00:44 > 0:00:47They cover almost the whole field of astronomy,
0:00:47 > 0:00:49which I most certainly do not.
0:00:49 > 0:00:50So, here they are. Good evening.
0:00:50 > 0:00:54Good evening, Patrick. I'm delighted to be talking about the infrared,
0:00:54 > 0:00:59because we can use it to look at the really cool stuff in the universe, by which I mean cold, of course.
0:00:59 > 0:01:03That seems a little counter intuitive but it makes some sense.
0:01:03 > 0:01:06We're used to looking at the universe with our eyes,
0:01:06 > 0:01:09we're used to getting visible light through telescopes and cameras.
0:01:09 > 0:01:13But we are biased towards the bits of the universe that shine,
0:01:13 > 0:01:16whether they're stars or even lightbulbs that shine
0:01:16 > 0:01:18and give out optical light.
0:01:18 > 0:01:20Most of the stuff we can see here,
0:01:20 > 0:01:22yourself, the table, even our guests here,
0:01:22 > 0:01:24we see them because they are reflecting that light.
0:01:24 > 0:01:28But they're also shining, they're shining in infrared.
0:01:28 > 0:01:31One way to think about that is to imagine a red hot coal.
0:01:31 > 0:01:34It will be giving off faint light
0:01:34 > 0:01:38but if you hold your hands out to the coal, you can feel heat.
0:01:38 > 0:01:43That heat is because of infrared radiation, just a longer wavelength form of the light.
0:01:43 > 0:01:47We can demonstrate this by playing with an infrared camera, Chris.
0:01:47 > 0:01:51Yes, so here we have a camera that's showing at the moment,
0:01:51 > 0:01:54Patrick in the infrared.
0:01:54 > 0:01:57So what we can see here is light Patrick is giving off.
0:01:57 > 0:02:00We can see that the yellow stuff is warmer
0:02:00 > 0:02:03and, Patrick, you have a cold nose.
0:02:03 > 0:02:05And a cold monocle.
0:02:05 > 0:02:09- Yes.- And also, a very black cat.
0:02:09 > 0:02:14Yes, so the picture of Ptolemy the cat in the infrared.
0:02:14 > 0:02:16We can scan this around the room.
0:02:16 > 0:02:20You can see that the things that are normally hidden are now seen -
0:02:20 > 0:02:25the camera crew and the lights are glowing in the infrared.
0:02:25 > 0:02:27And here we have John as well.
0:02:27 > 0:02:31- Very warm. - Not quite as cold a nose as Patrick.
0:02:31 > 0:02:36You can see this is a different view of the world from the visible universe
0:02:36 > 0:02:39because we have two mugs here that look pretty identical,
0:02:39 > 0:02:42filled with water and they look the same in the optical,
0:02:42 > 0:02:43but in the infrared, Chris?
0:02:43 > 0:02:47The one on the left is certainly black, so it is very cold
0:02:47 > 0:02:49and the one on the right is white hot.
0:02:49 > 0:02:53This is filled with hot water from the kettle, this is iced water.
0:02:53 > 0:02:56That's something you can't tell using optical light.
0:02:56 > 0:02:59You need the infrared or to pick them up
0:02:59 > 0:03:03and one of the problems with astronomy is, it's difficult to pick things up.
0:03:03 > 0:03:05It is indeed.
0:03:05 > 0:03:07What do we see when we point an infrared -
0:03:07 > 0:03:10or even a longer wavelength - telescope at the sky?
0:03:10 > 0:03:14The key difference from the optical, where we see stars,
0:03:14 > 0:03:16the hot things in the universe,
0:03:16 > 0:03:18we see the bits of the universe which are cold.
0:03:18 > 0:03:22So between the stars, which is largely empty space,
0:03:22 > 0:03:24there are clouds of gas and dust.
0:03:24 > 0:03:28They come in various forms but ones that are particularly interesting
0:03:28 > 0:03:31are called molecular clouds.
0:03:31 > 0:03:34In these clouds is a collection of molecules and dust particles.
0:03:34 > 0:03:38They are only maybe 10 degrees above absolute zero.
0:03:38 > 0:03:41- That's -273 Celsius.- Yes.
0:03:41 > 0:03:46These molecular clouds typically are at -263 degrees Celsius,
0:03:46 > 0:03:50or 10 degrees above absolute zero.
0:03:50 > 0:03:52Then there are little molecules
0:03:52 > 0:03:54in the clouds, different molecular species,
0:03:54 > 0:03:57and they rotate at different rates.
0:03:57 > 0:04:01They make jumps between different rotational states.
0:04:01 > 0:04:04When they do that, they emit little packets of light
0:04:04 > 0:04:06at particular distinct frequencies.
0:04:06 > 0:04:11The infrared telescope doesn't look like an ordinary telescope?
0:04:11 > 0:04:14Tell us about the James Clerk Maxwell Telescope, JCMT?
0:04:14 > 0:04:17Yes, the JCMT's a telescope that has been operating now
0:04:17 > 0:04:21on a remote mountain top in Hawaii for over 20 years now.
0:04:21 > 0:04:22It's a reflecting dish,
0:04:22 > 0:04:26a large reflecting telescope, 15m diameter.
0:04:26 > 0:04:29At the focus are these special far-infrared cameras
0:04:29 > 0:04:31that detect far-infrared radiation,
0:04:31 > 0:04:34a bit like the one demonstrated here.
0:04:34 > 0:04:38The really difficult thing is the detector has to be cold itself
0:04:38 > 0:04:41because otherwise all you see is the camera.
0:04:41 > 0:04:46Yes. The newest camera is called SCUBA-2
0:04:46 > 0:04:49It's a very new project.
0:04:49 > 0:04:52And inside there, there's a very large far-infrared camera
0:04:52 > 0:04:56that's cooled to only one-tenth of a degree above absolute zero.
0:04:56 > 0:04:59We should explain why the pictures look so terrible.
0:04:59 > 0:05:03For people used to looking at Hubble pictures,
0:05:03 > 0:05:06the visible, we're into the science of blobology here.
0:05:06 > 0:05:10Why is it so hard to get a decent image at these wavelengths?
0:05:10 > 0:05:13In far infrared, wavelengths are longer than in the optical.
0:05:13 > 0:05:15So although we have a 15-metre telescope,
0:05:15 > 0:05:18the resolution of the images we get isn't very good.
0:05:18 > 0:05:21The resolution of the James Clerk Maxwell Telescope
0:05:21 > 0:05:24is very similar to that of the unaided human eye.
0:05:24 > 0:05:27It's quite good, in terms of our daily lives,
0:05:27 > 0:05:30but in terms of detail for the study of astronomy,
0:05:30 > 0:05:34it's not good enough for many of the observations we want to make.
0:05:34 > 0:05:38Nonetheless, what can we see, for example, if we point it at M17?
0:05:38 > 0:05:42What we know is that, in these large molecular clouds,
0:05:42 > 0:05:45new generations of stars are forming as we speak.
0:05:45 > 0:05:49So by mapping the large structures in these molecular clouds,
0:05:49 > 0:05:52we can find where the new stars are forming.
0:05:52 > 0:05:55To take a very close look, we're going to need a different telescope
0:05:55 > 0:05:58and luckily, there's one being built.
0:05:58 > 0:06:03It's the most ambitious international collaboration in astronomical history.
0:06:03 > 0:06:05The telescope is called ALMA. It's down in Chile.
0:06:05 > 0:06:08A few years ago, I went to look at the site.
0:06:08 > 0:06:12Not much there then but things are pretty different now.
0:06:12 > 0:06:15ALMA was designed to work in the same part of the spectrum -
0:06:15 > 0:06:19the very far infrared as we observe with SCUBA-2 -
0:06:19 > 0:06:22but it was to address the fundamental problem with SCUBA-2.
0:06:22 > 0:06:25It's great for seeing big things in the universe
0:06:25 > 0:06:28and surveying where all the stars are forming,
0:06:28 > 0:06:31what we can't do is zoom in and look in very great detail.
0:06:31 > 0:06:34- ALMA can do that?- Yes. So, obviously the JCMT is a 15-metre dish
0:06:34 > 0:06:37and we worked out that to look at the detail
0:06:37 > 0:06:40we need a dish that's 15 km in size.
0:06:40 > 0:06:43Now, clearly, that's impossible to build.
0:06:43 > 0:06:45A bit difficult to steer!
0:06:45 > 0:06:47Yes! And way beyond our budget!
0:06:47 > 0:06:51We utilise the technique of radio interferometry.
0:06:51 > 0:06:54We recognise that, in fact, you don't need to build all the dish,
0:06:54 > 0:06:56the mirror, to make a good image.
0:06:56 > 0:07:00You can build parts of the mirror in different places.
0:07:00 > 0:07:05So, in this case, we've got a 15-kilometre-sized plateau
0:07:05 > 0:07:07up high in the Chilean Andes
0:07:07 > 0:07:10and we have 66 separate radio antennas,
0:07:10 > 0:07:13which are spread around the site,
0:07:13 > 0:07:16and we take the signals from each of those antennas
0:07:16 > 0:07:20and combine them in an electronic focus, if you like.
0:07:20 > 0:07:22From that electronic focus we can make images
0:07:22 > 0:07:26and it's as if our telescope had a diameter of 15 kilometres.
0:07:26 > 0:07:31So that means that images are 1,000 times more detailed than the JCMT.
0:07:31 > 0:07:35And so, for the first time, we actually now have, getting with ALMA,
0:07:35 > 0:07:37images that can compete, in resolution terms,
0:07:37 > 0:07:40with optical images, which is something that,
0:07:40 > 0:07:42I think, infrared astronomers
0:07:42 > 0:07:47have always been very jealous of optical astronomers! So we've talked about the technology
0:07:47 > 0:07:51and how complex it is and there's a lot of work going in around the world
0:07:51 > 0:07:54to build these, and some of that is taking place in the UK.
0:07:54 > 0:07:58I went to the Rutherford Appleton Laboratory in Oxfordshire to find out more.
0:08:00 > 0:08:04The Rutherford Appleton Laboratory has a worldwide reputation
0:08:04 > 0:08:07for building fabulous astronomical instruments
0:08:07 > 0:08:10which end up on telescopes all over the world.
0:08:10 > 0:08:13High in the Chilean desert,
0:08:13 > 0:08:17the ALMA telescopes are looking at the cold part of the sky
0:08:17 > 0:08:22and to do that, they need to be kept as cool as can be.
0:08:22 > 0:08:24Telescope dishes are big and impressive
0:08:24 > 0:08:25but they're just light buckets.
0:08:25 > 0:08:27It's the scientific instruments,
0:08:27 > 0:08:30the unsung heroes at the back of the telescopes,
0:08:30 > 0:08:33which do the hard work. It's their job
0:08:33 > 0:08:35to receive light collected by the dish
0:08:35 > 0:08:38and turn it into the amazing scientific results and images
0:08:38 > 0:08:40which will wow us.
0:08:41 > 0:08:44At the Rutherford Appleton Laboratory, Professor Brian Ellison
0:08:44 > 0:08:46is helping build the space-age refrigerators
0:08:46 > 0:08:49which will help keep the instruments cool.
0:08:49 > 0:08:53It's a chance for me to immerse myself totally
0:08:53 > 0:08:57in super-conducting tunnel junctions and local oscillators.
0:08:57 > 0:08:58Just my kind of fun!
0:08:58 > 0:09:00So, Brian, we've got in front of us
0:09:00 > 0:09:03the heart of one of the receivers of ALMA.
0:09:03 > 0:09:05Tell us what we're seeing here.
0:09:05 > 0:09:07OK, this is one of the super-conducting
0:09:07 > 0:09:09tunnel-junction receivers of ALMA
0:09:09 > 0:09:12that detects the energy from the telescope focus.
0:09:12 > 0:09:17What happens is that the signal from the telescope comes down through,
0:09:17 > 0:09:19bounces off various mirrors here
0:09:19 > 0:09:22and is brought to another focus at the detector, here.
0:09:22 > 0:09:27This device works at four degrees kelvin - four degrees above absolute zero -
0:09:27 > 0:09:32and picks up the energy, and that propagates down these cables here,
0:09:32 > 0:09:35at a frequency of about 4GHz,
0:09:35 > 0:09:37out through various components,
0:09:37 > 0:09:40it's amplified down through the rest of the structure
0:09:40 > 0:09:42and out to the outside world.
0:09:42 > 0:09:44So, this is one of the receivers,
0:09:44 > 0:09:46and there are quite a few in each cryostat.
0:09:46 > 0:09:49So if we look at the back of here,
0:09:49 > 0:09:51- we've got quite a range of them.- Yes.
0:09:51 > 0:09:54Here is the rear end of the ALMA receiver system.
0:09:54 > 0:09:56What you're seeing here is an array
0:09:56 > 0:09:59of the different local oscillator assemblies
0:09:59 > 0:10:02that provide the receiver reference signals.
0:10:02 > 0:10:05So we've got light coming in from the sky,
0:10:05 > 0:10:08compared with this reference source that comes in from the back,
0:10:08 > 0:10:10they're mixed at that detector we just saw
0:10:10 > 0:10:13and the resulting signal is fed out the back?
0:10:13 > 0:10:16The result's being fed out the back. Basically, it's a radio receiver
0:10:16 > 0:10:19but working at a much higher frequency than the average radio.
0:10:21 > 0:10:24So far, 16 of these space-age receivers
0:10:24 > 0:10:28have been fitted to telescopes on the Chajnantor Plateau,
0:10:28 > 0:10:30with 50 more to follow over the coming year.
0:10:30 > 0:10:33The ALMA telescope has already started giving us
0:10:33 > 0:10:36an amazing view of the Antennae galaxies.
0:10:36 > 0:10:38In visible light, we see two galaxies
0:10:38 > 0:10:40which are in the process of colliding,
0:10:40 > 0:10:42each containing billions of stars.
0:10:42 > 0:10:47With ALMA's ultra-cold eyes, we see the gas and dust between the stars,
0:10:47 > 0:10:50providing our first detailed view of the galactic crumple zone
0:10:50 > 0:10:52in which new stars are forming.
0:10:54 > 0:10:59ALMA is sure to amaze us even more over the years and decades to come,
0:10:59 > 0:11:03proving that it's cool to be infrared.
0:11:03 > 0:11:06We've been talking about telescopes on the ground.
0:11:06 > 0:11:08What about telescopes in space?
0:11:08 > 0:11:10Of course, so far,
0:11:10 > 0:11:14the most ambitious infrared telescope in space is Herschel.
0:11:14 > 0:11:16Herschel's been up for three years.
0:11:16 > 0:11:19It's the best far-infrared telescope we've got up in space.
0:11:19 > 0:11:21It's looking at wavelengths
0:11:21 > 0:11:24that are slightly warmer stuff than SCUBA-2 and ALMA,
0:11:24 > 0:11:25but one key thing is,
0:11:25 > 0:11:29these are wavelengths that are impossible to observe from the ground
0:11:29 > 0:11:33- because the atmosphere is, essentially, opaque over most of the range.- Yes.
0:11:33 > 0:11:35So, take the Pillars Of Creation from Hubble.
0:11:35 > 0:11:37It's one of the most iconic images.
0:11:37 > 0:11:39Dust clouds against a bright background.
0:11:39 > 0:11:42Oh, they're amazing things, yes.
0:11:42 > 0:11:43The optical light we're seeing
0:11:43 > 0:11:47is gas on the edges of these three fingers that are being energised,
0:11:47 > 0:11:50or ionised, by starlight from some nearby young stars.
0:11:50 > 0:11:53But if you look in the infrared, you're not seeing the gas,
0:11:53 > 0:11:55you're seeing the dust itself glowing.
0:11:55 > 0:11:58And what you can tell, from the temperature of the dust,
0:11:58 > 0:12:01you can see how many stars are heating the dust up
0:12:01 > 0:12:03and then you can see some very cold clumps.
0:12:03 > 0:12:05These are the stars that are starting to form.
0:12:05 > 0:12:08One of the interesting things about star formation
0:12:08 > 0:12:11is that the coldest things we know of in the universe
0:12:11 > 0:12:14are about to become the hottest things we know of in the universe!
0:12:14 > 0:12:19So we can see much more about where stars are forming and the environments they are forming in.
0:12:19 > 0:12:21But it can also look at enormous areas.
0:12:21 > 0:12:25You can get images with 6,000 galaxies in.
0:12:25 > 0:12:28The images are typically a few times the width of the moon across
0:12:28 > 0:12:30but if you take something that's the size
0:12:30 > 0:12:33of your little finger held at arm's length,
0:12:33 > 0:12:36there's still a thousand-odd galaxies in there.
0:12:36 > 0:12:40These are at times when the universe was only a few billion years old.
0:12:40 > 0:12:45One of the things Herschel can uniquely do is allow us to study water in the universe.
0:12:45 > 0:12:49Now, even in Chile on that very dry site,
0:12:49 > 0:12:52there's enough water in the atmosphere to block out the signals
0:12:52 > 0:12:55from water molecules emitting in these clouds.
0:12:55 > 0:12:59- It's not impressive to discover water in Earth's atmosphere. - No, that's right, but Herschel,
0:12:59 > 0:13:03being above the atmosphere, with it's very specialised receiver,
0:13:03 > 0:13:05can tune to some of the frequencies
0:13:05 > 0:13:08when the water molecules change their rotational state,
0:13:08 > 0:13:12and we can get these spectra of water in star-forming regions.
0:13:12 > 0:13:14The results are surprising, right?
0:13:14 > 0:13:17To a large extent, we've detected less water than expected
0:13:17 > 0:13:20based on models, so there's a mystery there
0:13:20 > 0:13:23to really understand the whole process by which water forms.
0:13:23 > 0:13:25We know it HAS to form, in quite large abundances,
0:13:25 > 0:13:27but the signals so far have been
0:13:27 > 0:13:29somewhat weaker than we're expecting.
0:13:29 > 0:13:33We've been talking about Herschel as one of the best infrared space telescopes.
0:13:33 > 0:13:36There's another one up there which is also very impressive
0:13:36 > 0:13:38and it's called the WISE satellite.
0:13:38 > 0:13:41That's been looking at slightly different wavelengths
0:13:41 > 0:13:43and I went to speak to one of the lead scientists, Amy Mainzer.
0:13:46 > 0:13:50NASA's big infrared mission, WISE, was designed to map the cosmos
0:13:50 > 0:13:55and also to discover new objects that no other telescope could see.
0:13:55 > 0:13:57It could only work for a year,
0:13:57 > 0:14:02but in that short time it collected an amazing amount of information.
0:14:02 > 0:14:06'Whilst in Nantes, France, I caught up with one of the team, Amy Mainzer.'
0:14:06 > 0:14:10- We collected millions of pictures. - Sure.
0:14:10 > 0:14:13We took a picture every 11 seconds for a year
0:14:13 > 0:14:15with a four-megapixel camera,
0:14:15 > 0:14:18so you can imagine that that builds up a lot of data very quickly.
0:14:18 > 0:14:22So imagine trying to go through that slideshow! It would take a while.
0:14:22 > 0:14:27Hiding in the dark and amidst all that data, was a strange object,
0:14:27 > 0:14:31and the WISE team found it - a new type of star.
0:14:31 > 0:14:34One of the most fun things that we've discovered
0:14:34 > 0:14:36so far with WISE is something called a brown dwarf,
0:14:36 > 0:14:40and it's a new class of brown dwarf that is actually room temperature.
0:14:40 > 0:14:43This is a star that can't even boil water.
0:14:43 > 0:14:46At its surface it's about room temperature - very cool -
0:14:46 > 0:14:48and it's basically kind of like
0:14:48 > 0:14:50a more massive version of Jupiter, if you will.
0:14:50 > 0:14:54These are things that are sort of halfway between the stars and the planets.
0:14:54 > 0:14:58They're probably more like a planet in some ways than a star.
0:14:58 > 0:15:01- OK.- And the processes going on in their core
0:15:01 > 0:15:05- are not quite the same as what goes on in a star like the sun.- Right.
0:15:05 > 0:15:07Some people call brown dwarfs failed stars.
0:15:07 > 0:15:11They are not very good at being stars because they can't fuse hydrogen into helium.
0:15:11 > 0:15:16What makes our sun glow is gravity is so powerful at the centre,
0:15:16 > 0:15:20it can take two hydrogen atoms and jam them together to make a helium.
0:15:20 > 0:15:22That releases a lot of energy
0:15:22 > 0:15:25but brown dwarfs just don't have the mass.
0:15:25 > 0:15:27They can't do it. They cannot make helium.
0:15:27 > 0:15:30- The density isn't high enough in the centre.- Just not enough.
0:15:30 > 0:15:34So they're kind of like wimpier versions of our sun. Lots wimpier!
0:15:34 > 0:15:35What happens is, when they form,
0:15:35 > 0:15:38as they collapse out of a cloud of gas and dust,
0:15:38 > 0:15:41they get hot in the middle but, unlike our sun,
0:15:41 > 0:15:45which then starts to shine of its own accord through fusion,
0:15:45 > 0:15:48these guys just cool off.
0:15:48 > 0:15:49You can see these with WISE,
0:15:49 > 0:15:53and you're finding them surprisingly close.
0:15:53 > 0:15:56Right. One of the things we're really interested in doing
0:15:56 > 0:15:59is seeing are there stars that are as close as the ones
0:15:59 > 0:16:00we know to be closest?
0:16:00 > 0:16:03Maybe there are stars that are even closer.
0:16:03 > 0:16:06So the search is on, we're hunting through these images right now
0:16:06 > 0:16:09to cull out things that look like they might be these very cold,
0:16:09 > 0:16:11very nearby brown dwarf stars.
0:16:13 > 0:16:17WISE has also been searching the cold, dark depths
0:16:17 > 0:16:20of our own solar system, hunting for asteroids.
0:16:20 > 0:16:23In particular, ones that could threaten Earth.
0:16:25 > 0:16:27We were actually able to observe
0:16:27 > 0:16:30more than 157,000 asteroids in our solar system.
0:16:30 > 0:16:32That's about a quarter of the known population.
0:16:32 > 0:16:34Most of these are in the main belt
0:16:34 > 0:16:40between Mars and Jupiter but we were also able to independently discover 33,000 so far
0:16:40 > 0:16:47- and that number keeps changing as more and more observations connect to other people's.- OK.
0:16:47 > 0:16:50- And you're analysing your data again and again?- That's right.
0:16:50 > 0:16:52One of the fun things is it's constantly changing.
0:16:52 > 0:16:54It's a fast-paced field - keeps us busy!
0:16:54 > 0:16:56Most asteroids stay in the main belt,
0:16:56 > 0:17:03- but some stray.- As of today we know of about 8,000 near-Earth objects
0:17:03 > 0:17:08that have been discovered by observers all over the world, going back hundreds of years.
0:17:08 > 0:17:13Today we have with WISE a different and unique sample,
0:17:13 > 0:17:17in the sense that because we observed these objects with infrared light,
0:17:17 > 0:17:22we were able to get really good measurements of sizes of asteroids.
0:17:22 > 0:17:24Mostly they look for visible light,
0:17:24 > 0:17:26so sunlight bouncing off the surface,
0:17:26 > 0:17:30- so they depend a lot on how reflective the surface is.- Right.
0:17:30 > 0:17:34That makes it hard to tell the difference between something
0:17:34 > 0:17:36small but bright and large but dark.
0:17:36 > 0:17:39Yes, a lot of these things,
0:17:39 > 0:17:43- like comets, are made of ice and therefore shiny.- Yes.
0:17:43 > 0:17:48There's a huge amount of diversity in all asteroids and comets.
0:17:48 > 0:17:51Just look at the average rocks you see on Earth.
0:17:51 > 0:17:53There's just as much diversity among asteroids.
0:17:53 > 0:17:57If we have both infrared and visible light, not only can we measure
0:17:57 > 0:18:01the sizes very well but also how much sunlight is reflected off the surface.
0:18:01 > 0:18:03So WISE had to be cool
0:18:03 > 0:18:07to work and that meant, eventually, the coolant ran out.
0:18:07 > 0:18:11- That's right. - So that part of its mission ended.
0:18:11 > 0:18:14Yes. The mission is now in honourable retirement.
0:18:14 > 0:18:16It completed all its mission goals and then some.
0:18:16 > 0:18:19We completed an extended mission and now we're done.
0:18:19 > 0:18:22The survey part is done and now we're processing the data.
0:18:25 > 0:18:28Big missions like WISE leave long legacies,
0:18:28 > 0:18:31and it will take many decades for astronomers to sift through
0:18:31 > 0:18:33the millions of images it has taken.
0:18:33 > 0:18:37Who knows what further discoveries will be made?
0:18:39 > 0:18:44WISE has finished its mission now but it was great to hear about it
0:18:44 > 0:18:47and the data will be useful. It does raise the question, John,
0:18:47 > 0:18:49how do you see these different surveys,
0:18:49 > 0:18:52on different scales, at different wavelengths,
0:18:52 > 0:18:54how do they come together?
0:18:54 > 0:18:59We're very lucky to have Herschel up and flying and operating
0:18:59 > 0:19:01and ALMA coming online simultaneously.
0:19:01 > 0:19:05It's by putting data together from those that we learn most
0:19:05 > 0:19:09and build up the spectral energy distribution of the object.
0:19:09 > 0:19:14So by building physical models of these objects and comparing them with the data,
0:19:14 > 0:19:17we can work out exactly how stars form.
0:19:17 > 0:19:21Let's say we gather here again in, what, let's say five years' time.
0:19:21 > 0:19:25Alma will be up and running. What do you think the big discoveries will have been?
0:19:25 > 0:19:27We already know there are
0:19:27 > 0:19:30lots and lots of extrasolar planets out there,
0:19:30 > 0:19:33so we know we have to have a way of forming those.
0:19:33 > 0:19:35So my hope, I suppose, for Alma is
0:19:35 > 0:19:38that over the next five, ten years of observing,
0:19:38 > 0:19:41we make good enough images of protoplanetary discs
0:19:41 > 0:19:45to really understand the details of how exactly stars form,
0:19:45 > 0:19:50where and when they form and how they maybe migrate through the disc to their current locations.
0:19:50 > 0:19:52Well, it's all fascinating stuff.
0:19:52 > 0:19:55John, Chris, Chris, thank you very much.
0:19:55 > 0:20:00So let's go now into my garden, where we find Pete and Paul
0:20:00 > 0:20:03also looking at the infrared sky.
0:20:05 > 0:20:09I think any chance of seeing stars tonight is wishful thinking.
0:20:09 > 0:20:11- Look at all the cloud. - It's a bit of a problem, isn't it?
0:20:11 > 0:20:14- There's a thick blanket of cloud up there.- Depressing.
0:20:14 > 0:20:17It looks pretty uniform when we look at it visually,
0:20:17 > 0:20:21but I have a very special camera here, which is an infrared camera.
0:20:21 > 0:20:24It's sensitive to the mid-infrared range.
0:20:24 > 0:20:28And when you point that one up to the sky, it can see clouds as well.
0:20:28 > 0:20:32Right. That's brilliant - a useful device!
0:20:32 > 0:20:36But, unlike when we're looking at the sky visually,
0:20:36 > 0:20:37seeing it as a uniform blanket of cloud,
0:20:37 > 0:20:41we can pick out structure in it looking through this camera,
0:20:41 > 0:20:43so it's good for picking out holes in the cloud.
0:20:43 > 0:20:48- I gather it's on me at the moment, so it can pick out my velvet jacket. - It can.
0:20:48 > 0:20:53- Basically, it's picking out all the different temperatures of your body as well.- The cold, cold hands.
0:20:53 > 0:20:57- It actually looks like you've got sunglasses on.- They're reflective.
0:20:57 > 0:20:59But the problem with infrared,
0:20:59 > 0:21:03if you're trying to look at stuff in the sky which is emitting infrared,
0:21:03 > 0:21:07is the Earth's atmosphere, the water vapour in the Earth's atmosphere.
0:21:07 > 0:21:10And that means that, for amateur astronomy,
0:21:10 > 0:21:14we have a bit of a problem, because unless we get rid of the atmosphere,
0:21:14 > 0:21:18we can't see anything in those ranges. But there are things we can do,
0:21:18 > 0:21:21mainly in the area of planetary imaging.
0:21:21 > 0:21:24On that subject, we have a little story.
0:21:24 > 0:21:28- I don't know if you're familiar with the Ashen Light.- Oh, yes.
0:21:28 > 0:21:33- It was seen by Giovanni Riccioli on January 9th 1643.- Right.
0:21:33 > 0:21:37And he noticed that there was this faint light on the dark side,
0:21:37 > 0:21:41the night side of Venus. It kind of looks a little bit like Earthshine.
0:21:41 > 0:21:44That's the effect when you get a really thin crescent moon
0:21:44 > 0:21:46- in the evening or morning twilight. - That's right.
0:21:46 > 0:21:49And that's caused by reflected light from the Earth.
0:21:49 > 0:21:52Of course, that can't possibly be the case with Venus.
0:21:52 > 0:21:56Really nothing to do with it on Venus. It's a very vague thing.
0:21:56 > 0:21:59Sometimes it covers the whole of the dark side of Venus
0:21:59 > 0:22:01and other times just portions of it.
0:22:01 > 0:22:04It's a sort of greenish glow, very subtle.
0:22:04 > 0:22:07I know you are quite sceptical. You've got that look in your face.
0:22:07 > 0:22:11"I don't believe a word of it. It's just visual, people seeing things."
0:22:11 > 0:22:14I think there is a genuine phenomenon there.
0:22:14 > 0:22:17There are a hell of a lot of reports about the Ashen Light.
0:22:17 > 0:22:19The problem is that when you have a crescent Venus,
0:22:19 > 0:22:23it looks like it really wants to complete the circle.
0:22:23 > 0:22:26I'm very open-minded. I'm quite happy if somebody comes along
0:22:26 > 0:22:30and says, "There's the Ashen Light, there it is," I'll be happy to accept that, obviously.
0:22:30 > 0:22:35But I have tried and tried, using near-infrared filters,
0:22:35 > 0:22:38because that's where it's supposed to be at its brightest,
0:22:38 > 0:22:41pushing the crescent of Venus off the side of the frame
0:22:41 > 0:22:43and upping the sensitivity of the camera,
0:22:43 > 0:22:45and I've picked nothing up.
0:22:45 > 0:22:48Tell you what, I'll bet with you within the next decade
0:22:48 > 0:22:50that it will have shown to be a genuine phenomenon.
0:22:50 > 0:22:53A decade's an awfully long time. OK, let's go for it.
0:22:53 > 0:22:56- You've witnessed this. - What do I win?- Respect.
0:22:56 > 0:22:58THEY LAUGH
0:22:58 > 0:23:01But Venus isn't the only thing we can do with infrared.
0:23:01 > 0:23:04- You've used it with Mars and Jupiter, haven't you?- Yeah.
0:23:04 > 0:23:08Basically, you use a near-infrared filter.
0:23:08 > 0:23:11When you look through one of these filters, it has the effect,
0:23:11 > 0:23:13because you're using a longer wavelength
0:23:13 > 0:23:16than the normal visual part of the spectrum,
0:23:16 > 0:23:18the seeing is a bit steadier.
0:23:18 > 0:23:22So that helps us if we're trying to take high-resolution images
0:23:22 > 0:23:24of, particularly, Mars, Jupiter,
0:23:24 > 0:23:26Saturn and the moon,
0:23:26 > 0:23:31because it allows us to get a much more steady view of these things.
0:23:31 > 0:23:34But also, the infrared actually starts to crisp up,
0:23:34 > 0:23:36it gives a greater contrast on some features,
0:23:36 > 0:23:40particularly with Mars, because Mars is a very reddish planet.
0:23:40 > 0:23:42So those albedo features are exaggerated.
0:23:42 > 0:23:45- They stand out brilliantly, actually.- Good.
0:23:45 > 0:23:47Sticking with Venus,
0:23:47 > 0:23:51- there's an interesting conjunction in March with Jupiter. - Yes, that's right,
0:23:51 > 0:23:53because Venus is moving away from the sun
0:23:53 > 0:23:56and Jupiter is marching in towards the evening twilight.
0:23:56 > 0:23:58So they'll have an encounter.
0:23:58 > 0:24:01They will have an encounter, which is called a conjunction,
0:24:01 > 0:24:04and that will occur or be at its best in the middle of March.
0:24:04 > 0:24:06That's going to be pretty spectacular,
0:24:06 > 0:24:08because you've got two really bright planets.
0:24:08 > 0:24:09Venus is the brightest of all.
0:24:09 > 0:24:13I think Mars can get marginally brighter than Jupiter.
0:24:13 > 0:24:16- Yeah, but not this time of year.- No.
0:24:16 > 0:24:19But when they're together, they're going to look like an amazing,
0:24:19 > 0:24:21really bright double star.
0:24:21 > 0:24:24- You're going to be out photographing them, aren't you?- Of course.
0:24:24 > 0:24:28It would be lovely to add some of these images to our Flickr site,
0:24:28 > 0:24:33- so if anybody does any infrared stuff or captures the Ashen Light... - Yeah, it'd be absolutely amazing.
0:24:33 > 0:24:35If you want to see all our lovely pictures,
0:24:35 > 0:24:42go to our BBC Flickr site, which is located at...
0:24:42 > 0:24:45All these wonderful objects in February and March, Pete -
0:24:45 > 0:24:47- aren't we lucky?- We are indeed.
0:24:51 > 0:24:53We've moved in from my garden with the two Chrises.
0:24:53 > 0:24:57First of all, this picture of the Helix Nebula,
0:24:57 > 0:25:00- and it's infrared and it's a lovely picture.- It's a wonderful image,
0:25:00 > 0:25:04Patrick, in the infrared from the VISTA telescope down in Chile.
0:25:04 > 0:25:06It really shows the interaction between the gas,
0:25:06 > 0:25:09which is the outer layers of a sun-like star
0:25:09 > 0:25:11near the end of its life that's been shed,
0:25:11 > 0:25:12and the star itself.
0:25:12 > 0:25:14You can see these dusty rings of different layers,
0:25:14 > 0:25:20then you see these fingers which are being illuminated by the central star.
0:25:20 > 0:25:25- It's an incredible image and a beautiful object. - Another thing that's near the sun
0:25:25 > 0:25:27and has survived so far is a sun-grazing comet.
0:25:27 > 0:25:30This comet goes by the name Comet Lovejoy,
0:25:30 > 0:25:31named after Terry Lovejoy,
0:25:31 > 0:25:33who discovered it at the end of last year.
0:25:33 > 0:25:36And it went incredibly close to the sun.
0:25:36 > 0:25:39It went within about 140,000 kilometres of the sun,
0:25:39 > 0:25:41incredibly close and hot.
0:25:41 > 0:25:44You would expect a comet that goes that close to be broken up
0:25:44 > 0:25:48and to evaporate, and that's what was expected to happen as this comet went past the sun,
0:25:48 > 0:25:51then miraculously, it came out the other side intact.
0:25:51 > 0:25:54So it must have been much bigger than it was previously thought,
0:25:54 > 0:25:59- to have survived the encounter. - Some of the images are gorgeous. We can see this glorious comet.
0:25:59 > 0:26:02Why couldn't this have happened in the north of the sky?
0:26:02 > 0:26:07- Why didn't it come closer to the Earth?- This is just not fair, but a beautiful comet nonetheless.
0:26:07 > 0:26:10I hadn't realised that all of these sun-grazer comets, most of them
0:26:10 > 0:26:13are supposed to come from the break-up of a single larger body
0:26:13 > 0:26:14not that long ago,
0:26:14 > 0:26:19so we're seeing the dying embers of a past massive comet. Rather wonderful.
0:26:19 > 0:26:23Well now, also, yet more tenants of other stars.
0:26:23 > 0:26:25I'm getting a bit tired of these.
0:26:25 > 0:26:27Well, these are exciting ones.
0:26:27 > 0:26:32I know what you mean, but our last programme was on exoplanets,
0:26:32 > 0:26:33and we just caught the discovery
0:26:33 > 0:26:37of the first unambiguously Earth-sized and Venus-sized worlds.
0:26:37 > 0:26:38But it's been topped already,
0:26:38 > 0:26:40and we have three Mars-sized bodies.
0:26:40 > 0:26:44They were able to be detected because they're close to their parent star.
0:26:44 > 0:26:47And so we're really getting down to rocky planets now,
0:26:47 > 0:26:50and they too, I think, will turn out to be common.
0:26:50 > 0:26:54In fact, we have a survey that used a technique called microlensing,
0:26:54 > 0:26:57looking for the bending of light from distant stars.
0:26:57 > 0:27:00A team looking at this microlensing data predicted this week
0:27:00 > 0:27:05that there are probably 100 billion planets, at least, in our galaxy,
0:27:05 > 0:27:08so you're going to be bored of them for a while yet, Patrick.
0:27:08 > 0:27:11Many of those must contain life. I wonder, what is life?
0:27:11 > 0:27:13Well, let's hope they're watching.
0:27:13 > 0:27:16But let's come back to your province, let's leave life alone
0:27:16 > 0:27:20for this month and talk about the moon, because there's a new NASA mission.
0:27:20 > 0:27:23- Yes, and an interesting one, too. - Yes, this is a mission called GRAIL.
0:27:23 > 0:27:28'Zero, and liftoff of the Delta 2 with GRAIL,
0:27:28 > 0:27:31'journey to the centre of the moon.'
0:27:31 > 0:27:32It's two spacecraft.
0:27:32 > 0:27:35They're going to fly in immense precision around the moon,
0:27:35 > 0:27:39and as they do so, as they pass over massive regions, they will dip,
0:27:39 > 0:27:42and as they pass over less dense regions, they will rise
0:27:42 > 0:27:44just by the differences of the moon's gravity.
0:27:44 > 0:27:48By doing that, they plan to map the interior of the whole moon
0:27:48 > 0:27:50and we'll get a sense of how the moon formed.
0:27:50 > 0:27:53And it will tell us about why the near side of the moon
0:27:53 > 0:27:55is so different from the far side.
0:27:55 > 0:28:00We think that's because of how the moon formed. Hopefully the GRAIL satellites, which have been renamed
0:28:00 > 0:28:03by some students in America who won a competition...
0:28:03 > 0:28:07Instead of GRAIL A and GRAIL B, they're now called Ebb and Flow.
0:28:07 > 0:28:08THEY LAUGH
0:28:08 > 0:28:12- Oh, dear! And with that, I think we'll say good night!- Yes.
0:28:12 > 0:28:14I'll be back next week,
0:28:14 > 0:28:18this time talking about amateur astronomers and the work they do in astronomy,
0:28:18 > 0:28:21which, believe me, is really considerable.
0:28:21 > 0:28:24So, for now, from all of us, good night.
0:28:29 > 0:28:31Subtitles by Red Bee Media Ltd