:00:09. > :00:12.Last night we looked at the supermassive black hole at the
:00:12. > :00:17.centre of our galaxy, tonight we are hunting aliens.
:00:17. > :00:21.We will be revealing, and how incredible is this, how you at home
:00:21. > :00:24.helped us to discover a brand new planet.
:00:24. > :00:34.I'm Brian Cox and this is Dara O'Briain, and this is Stargazing
:00:34. > :00:54.
:00:54. > :00:58.Welcome back to the control room here in Jodrell Bank Observatory
:00:58. > :01:01.for the third and final night of this year's Stargazing live, we are
:01:01. > :01:05.going to be tackling perhaps the biggest question in all of science,
:01:05. > :01:09.are we alone in the universe? are living in a revolutionary
:01:09. > :01:13.period in a search for life beyond earth, we are now able to find
:01:13. > :01:19.planets billions of miles outside our Solar System. They are called
:01:19. > :01:23.exo-planets, so far we have found over 700 of them. Last month
:01:23. > :01:27.scientists announced the discovery of Kepler 22b. A planet quite close,
:01:27. > :01:32.about ten light years away, it is thought to be the closest one we
:01:32. > :01:38.have come across beyond our Solar System. This is an artist
:01:38. > :01:42.impression. It is earth-like with an atmosphere. That is because it
:01:42. > :01:47.probably is earth-like at moss stpeers and could be a strong
:01:47. > :01:53.candidate -- atmosphere, and could be a strong candidate for life.
:01:53. > :02:01.can actually listen to Kepler 22b. Are we there with the co-ordinates,
:02:01. > :02:06.I have to hit "return ", are you sure, there is a genuine note of
:02:06. > :02:10.peril. Bingo, a monkey can do that. That will turn to face directly to
:02:10. > :02:13.Kepler 22b. Later, as it has turned around, we can listen to it. We
:02:14. > :02:19.will tell you about the planet at home you have found.
:02:19. > :02:24.Last night we looked at light pollution, all the artificial light
:02:24. > :02:27.that obscures the stars in the night sky. To tell you the light a
:02:27. > :02:32.smallest place can create, we asked landmarks across the country to
:02:32. > :02:37.turn their lights out. We tried to convince an entire town to switch
:02:37. > :02:42.their lights off live on aifrplt standing by in Dulverton is Mark, -
:02:42. > :02:46.- live on air. Standing by in Dulverton is Mark. What is
:02:47. > :02:50.happening? It is wet here in Dulverton, the
:02:50. > :02:57.atmosphere is electric. It is a small town. I'm here on the high
:02:57. > :03:01.street of Dulverton, a small town with 1600 inhabitant, 800 houses,
:03:01. > :03:04.50 shops, bars and restaurants. We have tried to spread the word to
:03:04. > :03:06.get people to think about their lighting.
:03:07. > :03:12.The weather doesn't look particularly good, does that mean
:03:12. > :03:18.if the lights are out you won't suddenly see the Milky Way in all
:03:18. > :03:22.its glory, you won't see a great show overhead? Not amazing in stars,
:03:22. > :03:26.the clouds are looking stunning. Over the past few weeks we have had
:03:26. > :03:30.teams working in Dulverton to spread the word. In 20 minutes time,
:03:30. > :03:38.when the bells ring, we will find out how successful that message has
:03:38. > :03:45.spread. As this film shows, the message or task was not an easy one.
:03:45. > :03:49.Dulverton has 720 houses, 177 street lights, 40 shops and cafes,
:03:49. > :03:54.three schools, three pubs, and a sports ground. That is a lot of
:03:54. > :03:58.lights. If this is going to work, we will need to get the whole town
:03:58. > :04:01.on board. First things first, we had to meet with the mayor. What do
:04:01. > :04:05.you think will be the biggest challenge for us? Getting out the
:04:05. > :04:10.word to everybody that they should do what we want them to do that is
:04:10. > :04:14.to make the big switch off, the biggest we could ever make.
:04:14. > :04:20.knocked on hundreds of doors, dropped leaflets through
:04:20. > :04:27.letterboxes and spoke to as many residents as we could find. Can you
:04:27. > :04:31.turn that off for us? Hello, what lights do you normally
:04:31. > :04:36.have on? Maybe the upstairs light. Most of the lights, yeah.
:04:36. > :04:38.Thank you very much indeed for your support. Thank you too.
:04:38. > :04:42.I'm exhausted, I have been delivering leaflets all day, but
:04:42. > :04:47.the response, I think, has been pretty positive. I just hope they
:04:47. > :04:51.weren't telling me that to get me off their doorsteps. Dulverton is
:04:51. > :04:56.part of Exmoor National Park, with some of the darkest skies in the UK.
:04:56. > :05:00.Even this relatively small town generates enough life to obliterate
:05:00. > :05:03.the skies with a fuzzy orange glow. Light pollution doesn't just reduce
:05:03. > :05:08.the visibility of stars, light that shines where it isn't needed is a
:05:08. > :05:11.waste of energy and money. We have chosen Dulverton as our switch-off
:05:11. > :05:15.challenge, but there are thousands of towns and cities all over the
:05:15. > :05:19.country that could benefit from a little less light.
:05:19. > :05:24.Only a few days to go. This morning, one of schools in Dulverton has
:05:24. > :05:28.allowed me to take the school assembly. I'm a bit nervous, I have
:05:28. > :05:33.not done that since I was in school. If I can get the kids on board, I
:05:33. > :05:36.can get the parents on board. What we need you all to do is go home
:05:36. > :05:42.tonight, when you finish school, get all of your parents to turn off
:05:42. > :05:45.all the lights in your house. Are you going to help us? Yeah!
:05:45. > :05:50.What we need now is some kind of signal to make sure that all the
:05:50. > :05:55.lights are switched off at exactly the same time. I have arranged a
:05:55. > :05:58.meeting with the church bell ringers. Will everyone in Dulverton
:05:58. > :06:01.hear the signal? If the wind is in the east they will hear it, if it
:06:01. > :06:06.is in the west they won't. If the wind is blowing in the wrong
:06:07. > :06:12.direction no-one will hear it? Crikey, this might work and it
:06:12. > :06:15.might not. Now I have to see man about street lights. The majority
:06:15. > :06:21.of the lights will have to be visited individually. We can't push
:06:21. > :06:27.a red button and they all go off? Perhaps 20 years ago, but not now.
:06:27. > :06:30.It is a big job k we do it? Yes. have visited businesses and
:06:30. > :06:33.thousands, we have spoken to the local mayor, the police are
:06:33. > :06:43.shutting off roads for us, posters around the town, I don't know if
:06:43. > :06:44.
:06:44. > :06:49.this will work f it does, it will As you can see, the residents have
:06:49. > :06:52.turned out in their hundreds to support this, including some hardy
:06:52. > :06:56.astronomers, we have done everything we can do. In 15 minutes,
:06:56. > :07:00.when the bells cliem chime, we will be entirely in the hands of the
:07:00. > :07:03.good people of Dulverton. The weather isn't looking great, we
:07:03. > :07:08.will persevere, getting those lights off will be an achievement
:07:08. > :07:12.in itself. We will be back shortly This is turning around in its own
:07:13. > :07:21.stately well. We gave the wrong information earlier.
:07:21. > :07:26.Kepler 22b, is still relatively close, 600 million light years away.
:07:26. > :07:30.You have sent us in stunners from home.
:07:30. > :07:35.This is a photograph of a star I know well, because we talked about
:07:35. > :07:43.it on Wonders of the Universe. There it is.
:07:43. > :07:53.It is star called, this is the Triang ulumGalaxy, I wasn't going
:07:53. > :07:53.
:07:53. > :07:59.to talk about that. But it is nice. This is the Rising Sun, and finally,
:07:59. > :08:03.I think this is particularly nice, it was taken by Steve, one of the
:08:03. > :08:07.astronomers we had out in the dark, muddy field over there on Monday
:08:07. > :08:14.night. We do need you to keep them coming in, you will find details of
:08:14. > :08:20.how to get them on the website -- to get them to us on the website. I
:08:20. > :08:25.had a viewer asking for the website address. I have no idea. It is
:08:25. > :08:30.below. I can't bear to read it out, I have read it out so many times.
:08:31. > :08:36.You can join in on the live talk, Dr Lucie Green is standing by to
:08:36. > :08:38.answer all guess, and on Stargazing Back To Earth following the
:08:38. > :08:41.programme. We have questions for Brian too. We will get to the
:08:41. > :08:43.questions for Brian later on. If you have a question,
:08:43. > :08:49.particularly if there is anything you want to know about planets or
:08:49. > :08:58.the search for life, you can get them to us by e-mailing the address
:08:58. > :09:01.below, or the Twitter address. wanted you to say it!
:09:01. > :09:05.Although we are spending a lot of time looking for life and exo-
:09:05. > :09:07.planet, the best chance of finding life in the Solar System comes not
:09:07. > :09:11.from the planet, but probably the moons.
:09:12. > :09:16.We have probes all across the Solar System, the majority of the planets
:09:16. > :09:20.we have probes, what are the best bets for finding them? This is a
:09:20. > :09:25.picture of probably what most people think is the strongest
:09:25. > :09:31.candidateor life beyond earth, this is Jupiter's moon, Europa, this was
:09:31. > :09:35.taken by the Galileo Probe, it crashed into Jupiter. One of the
:09:35. > :09:39.reasons it did that was to avoid Europa. It is thought it is just
:09:39. > :09:43.possible we could have contaminated it if we crashed the probe in it.
:09:43. > :09:48.Rather than landing the probe it was ditched? Yeah, into Jupiter.
:09:48. > :09:53.The reason we are very excited by Europa, is it almost certainly has
:09:53. > :09:57.an ocean of liquid water beneath the icey surface, there is probably
:09:57. > :10:03.more water in the oceans of Europa, than in all the oceans of earth
:10:03. > :10:09.combined. It is a fascinating world. The problem is the ice is probably
:10:09. > :10:14.about 100kms thick, it would take a big drill to get through. It is a
:10:14. > :10:19.target for exploration. The reason we know, this is a close-up of the
:10:19. > :10:25.surface, you can see the cracks, they are very reminiscent of the
:10:25. > :10:30.cracks in sea ice, when you model that, it indeed seems there are
:10:30. > :10:36.cracks constantly shifting, because this ice is floating on an ocean of
:10:36. > :10:41.lifting water. There is another of Jupiter's moons, Al-Ganzouri, we we
:10:41. > :10:45.mentioned, -- Ganymede, it is also candidate. It has if not an ocean,
:10:45. > :10:49.then liquid water beneath the surface. We think it probably looks
:10:49. > :10:52.like this, this is the cross section of Ganymede, there is icey
:10:52. > :10:59.sludge there. NASA are going to Mars later in the
:10:59. > :11:04.year with the new Curiosity Rover, following the water and following
:11:04. > :11:09.the complex carbon molecules in organic chepls treatment that will
:11:09. > :11:16.specifically land in places where they need -- chemistry, that will
:11:16. > :11:25.specifically land in places where there are water. You find mineral
:11:25. > :11:29.deposits, this is from the Opportunity Rover, g ipsumhas been
:11:29. > :11:33.found in Mars, it is only found in the presence of standing water, it
:11:33. > :11:37.is probably the same on Mars, we know there was water there once.
:11:37. > :11:43.That is from Mars, we will receive information next year, if we're
:11:43. > :11:53.back next year we will show you the news from Mars.
:11:53. > :11:55.
:11:55. > :11:59.Over to Liz. Welcome back to the South African
:11:59. > :12:04.astronomical observatory. We are at the one metre telescope, British-
:12:04. > :12:08.built in Newcastle. Normally this telescope looks at objects far
:12:08. > :12:13.beyond our Solar System, take a look at this image it has taken of
:12:14. > :12:18.Saturn, 900 million miles away from us. Neptune is our outer most
:12:18. > :12:22.planet in the Solar System, another two billion miles outside Saturn.
:12:22. > :12:32.That is not where the Solar System ends, in fact, we have still a lot
:12:32. > :12:36.
:12:36. > :12:40.to learn about this very mysterious The Karoo desert might look more
:12:40. > :12:47.like an alien landscape than in Britain, but this place is still
:12:47. > :12:51.unmistakically part of our home, planet earth. Fertile soils, the
:12:51. > :12:56.warmth from our sun, a great diversity of living things. It is
:12:56. > :13:01.all down to our unique position in the Solar System. Where the third
:13:01. > :13:05.rock from the sun, not too hot, not too cold, just right for life to
:13:05. > :13:15.flourish. Of course, we are just one of a
:13:15. > :13:19.
:13:19. > :13:27.family of planets. If my rucksack is the sun, we have rocky planets
:13:27. > :13:33.first, Mercury, Venus, our own planet earth and Mars, then the gas
:13:33. > :13:37.giants, Jupiter and Saturn, Uranus, Neptune and Pluto. Which has been
:13:37. > :13:42.reclassified as a dwarf planet, it is no longer a planet. Then what
:13:42. > :13:49.happens? What lies beyond our eight planets? And where does our Solar
:13:49. > :13:54.System actually end? Amanda is an astronomer working here in South
:13:54. > :13:57.Africa, she specialises in the distant objects that inhabit the
:13:57. > :14:01.remotist regions of our Solar System.
:14:01. > :14:06.If this is Neptune, what is going on between it and the nearest star,
:14:06. > :14:10.over the horizon if it is four light years away or more, is it all
:14:10. > :14:17.empty space? It is hardly empty space, we have discovered a lot of
:14:17. > :14:22.objects out there, rocky objects, they are called the Kuiper Belt.
:14:22. > :14:27.There are 70,000 out there we think. That sounds like a lot of objects
:14:27. > :14:33.swimming around in the area. 70,000 are the biggest ones, if you go
:14:33. > :14:38.down to the smaller ones we think it is billions. How wide is it?
:14:38. > :14:44.you think of how far Neptune is from the sun, the classic Kuiper
:14:44. > :14:48.Belt is that far from Neptune. is wide, does that mean Pluto is
:14:48. > :14:52.officially a Kuiper Belt object? is in that Kuiper Belt, it was one
:14:52. > :14:56.of the first objects to be discovered. If we have gone that
:14:56. > :14:59.distance from the sun to newspaper tune again, that is the Kuiper Belt,
:14:59. > :15:03.here it is at the edge of the Kuiper Belt, what happens here, is
:15:03. > :15:08.this the edge of our Solar System? Not yet, we still have objects that
:15:08. > :15:13.were discovered out here that have objected that go -- orbited that go
:15:13. > :15:17.beyond the Kuiper Belt, we call them the scattered disc. How many
:15:17. > :15:23.objects exist there? Maybe hundreds, a few very well known, though.
:15:23. > :15:28.There is one called Aris, it is about three-times as far away from
:15:28. > :15:33.the sun as Neptune is now. What does it look like? We have images
:15:33. > :15:36.from the Hubble Space Telescope. is a bit blury? From the image you
:15:36. > :15:40.are seeing reflected light, there are severe limitations to doing
:15:40. > :15:44.that kind of imaging. That is the furthest object we have seen with
:15:44. > :15:48.the telescope. When you get to the edge of the scattered disc, surely
:15:48. > :15:53.that is the edge of the Solar System? No, there is more. Beyond
:15:53. > :16:03.that is a structure that we have they areised called the Oort Cloud,
:16:03. > :16:07.hundreds of thousands of objects srpbd the Solar System, two light
:16:07. > :16:11.years away. Is that the end of the Solar System? If you want to call
:16:11. > :16:15.it that, that is as far as we know, as far as the sun's gravitational
:16:15. > :16:19.influence he can tends. I would say it is pretty much the end of the
:16:19. > :16:25.Solar System. How do we know what this Oort Cloud
:16:25. > :16:31.looks like if it is hypothetical? We have observational evidence in
:16:31. > :16:36.the form of comets, they come from all different directions, when we
:16:36. > :16:40.trace their orbits they come from far away, distant parts of the
:16:41. > :16:50.Solar System. Do all comets come from the Oort Cloud? No, we had a
:16:51. > :16:51.
:16:51. > :16:56.comet visible from here, Comet Love Joy, take a photograph here of by
:16:56. > :16:59.one of the IT guys. Your expertise is the Kuiper Belt and the
:16:59. > :17:04.scattered disc, you say it is difficult to get information from
:17:05. > :17:13.the images of the objects, how do you study them further? We have to
:17:13. > :17:16.be creative, we have the stellar augmentation. We look at the
:17:16. > :17:20.objects passing across the scattered discs, and the shadow, we
:17:20. > :17:24.learn about the size, properties for the atmosphere, how the
:17:24. > :17:29.atmosphere might be changing, we combine that with things we know
:17:29. > :17:33.and get the density. It is easy to know where the shadows are cast on
:17:33. > :17:36.the planet? It is really hard, we spend a lot of time measuring. A
:17:36. > :17:40.shadow Pat can come across Sutherland and we can be lucky,
:17:40. > :17:44.there is a lot of telescopes, sometimes not, then it gets
:17:45. > :17:50.exciting. Last year I rented a pick-up truck in Cape Town and
:17:50. > :17:57.putting a 12-portable telescope in the back, and one of our
:17:57. > :18:02.instruments built for the purpose, we crossed the border in Namibia,
:18:02. > :18:07.and put all this equipment out, and looking over our shoulder all the
:18:07. > :18:11.time for animals. You were tracking an interesting object? It was a
:18:11. > :18:15.large Kuiper Belt object, it was a strange result, it suggests the
:18:15. > :18:24.object is really elongateed, that is not what we would have expected.
:18:24. > :18:29.Come back to us later, I will be finding out about superWASP-.
:18:29. > :18:34.Discussion as it,were the edge of the solar -- discussing as they
:18:34. > :18:40.were the edge of the Solar System, which Voyager is heading there now?
:18:40. > :18:44.It is one of the great stories in space exploration, launched in 1977,
:18:44. > :18:49.Voyager 1 and 2. They were launched to do the grand tour of the Solar
:18:49. > :18:52.System. At that time you launched a spacecraft, you could visit Jupiter,
:18:53. > :18:58.Saturn, Uranus and Neptune in one mission. It happens very rarely.
:18:58. > :19:02.Off they went, ambitious spacecraft. I remember talking to one of the
:19:02. > :19:05.designers, they were designed to last two or three years, four years.
:19:05. > :19:09.It was expensive saying this spacecraft will last for 20 year,
:19:09. > :19:14.you have to build it like a tank. I have a picture of it there. It is
:19:14. > :19:22.about the size of a bus, or a car. It is a tiny little thing. At the
:19:22. > :19:28.moment Voyager 1, the most distant man made object. It is 17 million
:19:28. > :19:32.kms away -- 17 million kilometres away, 14 times the distance from
:19:32. > :19:38.the earth to the sun. It is powered by a little battery and can be
:19:38. > :19:42.detected now. What the Voyager 1 has done and II, is the place where
:19:42. > :19:46.the wind from the sun meets the wind from interstellar space, they
:19:46. > :19:50.are measuring that, the instruments are still working, and they send
:19:50. > :19:54.the data back. The coolist thing is they do it on a tape. Most of our
:19:54. > :19:59.viewers under the age of 20 won't know what a tape is. It is a piece
:19:59. > :20:05.of magnetic brown stuff used to record Top Of The Pops on. It
:20:05. > :20:08.records the data, every so often it gets its transmitters point it at a
:20:08. > :20:13.telescope and sends the information back. NASA are saying they are
:20:13. > :20:18.turning off some of the parts of it now to conserve energy, they think
:20:18. > :20:22.they can keep it going until 2025? The heat has been turned off, it is
:20:22. > :20:27.one of the coldest working things we have built, it is sending
:20:27. > :20:34.information and should keep working until 2025. That is a brilliant
:20:34. > :20:38.example of the things we can do when we put our minds to it. Before
:20:38. > :20:43.we go back to Dulverton have a look at this? This is Britain on a clear
:20:43. > :20:52.night from space. You can see the major cities, London, Birmingham,
:20:52. > :20:56.Manchester, Edinburgh, Newcastle. It is a mess, basically. 60% of us
:20:56. > :20:59.live in a severely light polluted area, it plays havoc with
:20:59. > :21:06.stargazing, it is not difficult to reduce. Several iconic buildings
:21:06. > :21:11.have been leading the way for us. This is Worcester Cathedral, they
:21:11. > :21:14.switched off. Here is Bristol's Clifton Suspension Bridge.
:21:14. > :21:19.Even down in Cornwall, the Eden Project, they have been dimming
:21:19. > :21:24.their lights for us in order to get a clear view of the sky. We have
:21:24. > :21:29.the tower in Portsmouth. There it goes.
:21:29. > :21:35.This is BBC Media City in Salford, witching off its lights.
:21:35. > :21:38.We want to see just -- switching off its lights. We want to see the
:21:39. > :21:44.big difference switching off lights can make, even in a small town. It
:21:44. > :21:48.is time for Dulverton to switch off. This is it, after months of
:21:48. > :21:52.planning, the bells are going to ring very soon, and hopefully it
:21:52. > :21:57.will be very dark. We need everyone in Dulverton to turn their lights
:21:57. > :22:02.off as soon as you hear the bells ringing. I will invite my posse to
:22:02. > :22:06.help with the countdown. I was going to say, are you ready
:22:06. > :22:11.for this, Dulverton? I think you are.
:22:11. > :22:21.(cheering) We are now going to start the countdown.
:22:21. > :22:22.
:22:22. > :22:30.5-4-3-2-1. (bells ringing) This is the moment
:22:30. > :22:39.where the bells should start ringing, instead, I want you all to
:22:39. > :22:47.shout "ding dong". We can hear the bells, we can see
:22:47. > :22:52.the lights going out. Except for the place beside you. So far the
:22:52. > :22:58.lights in the street has have all gone out. It is really eerie. It is
:22:58. > :23:05.bizarre. Look at that. It is a shame that you can't see the sky.
:23:05. > :23:09.There it is. This is amazing, I can barely see the camera in front of
:23:09. > :23:13.me, it has got so dark. We can't see the sky. What I would say,
:23:13. > :23:16.eventhough it is cloudy, the sky has leapt out above our heads. We
:23:16. > :23:20.have special night vision cameras, because there is no light around.
:23:20. > :23:26.It looks incredible. But it is going to take a while for our eyes
:23:26. > :23:29.to adapt to the darkness, come back in a few moments and see how we are
:23:29. > :23:34.getting on. It is a wonderful moment that, it is easy to treat it
:23:34. > :23:37.as a bit of a stunt, it is cloudy so you don't see the stars come out.
:23:37. > :23:41.There is a genuine point about losing contact with the night sky.
:23:41. > :23:45.If you think back to the time, you heard how old you are, you can't
:23:45. > :23:50.think back to the time before electricity. But the stars were
:23:50. > :23:54.visible, they were part of our lives. It is the foundation of
:23:54. > :23:57.science, astronomy is the oldest science, the motivation to
:23:57. > :24:00.understand the view that if you live in a city all your life, you
:24:00. > :24:04.don't see it. It is a powerful thing to do.
:24:04. > :24:09.It is very striking, we know we are doing it on bad day. We know the
:24:09. > :24:12.weather wasn't perfect, but if they can do it for us now, there is no
:24:12. > :24:16.reason they can't do it at a better time of year. Because it is the
:24:16. > :24:23.last show, I usually answer the questions, but because Dara has a
:24:23. > :24:27.degree of physics and cosmology from one of Ireland's premier
:24:28. > :24:32.institutions. Dara will be answering the questions.
:24:32. > :24:36.Katie asks, why doesn't planets twinkle in the sky? I always
:24:36. > :24:39.presume it is because they were further away and more chance of
:24:39. > :24:43.fragments of dust and other things to pass away. It is not, because
:24:43. > :24:47.they are so far away, they are a point source of life, a single beam
:24:47. > :24:52.of life light, when it hits the atmosphere and gets bounced around,
:24:52. > :24:56.it gets deflected, much better than planets who have a number of points.
:24:56. > :25:00.They are bigger, it is extended source, that is the term for it. It
:25:01. > :25:05.is easier for them when they come into the atmosphere to remain
:25:05. > :25:10.coherent. That is the only one we have time for. 100% record. If we
:25:10. > :25:14.find life in the Solar System, it will only be certainly at the
:25:14. > :25:20.microbe level. If we want to find substantial life forms, we have to
:25:20. > :25:27.search for planets much further out in space. Take a look at this image
:25:27. > :25:31.found by the Hubble Space Telescope, it is called Fomalhaut.
:25:31. > :25:35.It is a star called Fomalhaut. have removed the star from the
:25:35. > :25:39.image, the bright centre is gone, we can see around it. What you are
:25:39. > :25:42.looking at is a very young star, a bright blue star. It is one of the
:25:42. > :25:48.brightest stars in the sky, it is in the southern Hemisphere so we
:25:48. > :25:54.can't see T it is a very young star. -- it. It is a very young star. You
:25:54. > :25:58.are looking at a prime mordal disc. That is what our Solar System may
:25:58. > :26:01.have looked like over four billion years ago. That is interesting. It
:26:01. > :26:05.is a beautiful image. The most interesting thing about this n this
:26:05. > :26:10.square here, it is blown up. There is a large object here. It is
:26:10. > :26:16.actually a very large object. It is, in fact, a planet, in a very early
:26:16. > :26:21.stages of its formation. How rare is that to see. Has it ever been
:26:21. > :26:26.seen? No planet had been photographed before. They are
:26:26. > :26:30.extremely faint. It was all the techniques outlined in the
:26:30. > :26:35.programme. This shubl pays telescope image is a planet. It
:26:35. > :26:40.wasn't moved there in -- Hubble Space Telescope image is a planet.
:26:40. > :26:46.It is a long way out from the star. Is it gathering up and building up
:26:46. > :26:51.dust, like the process which our planets were made. We think planets
:26:51. > :26:55.begin very small, only a kilometer across or smaller, over time in
:26:55. > :26:59.collisions they aggregate, the biggest ones begin to suck up all
:26:59. > :27:05.the dust. Eventually in that system you will get a clean Solar System
:27:05. > :27:10.like we get today. Scientists have discovered 700 exo-planets, each
:27:10. > :27:19.and every one of these discoveries have been made in the last 20 years.
:27:19. > :27:25.We have been looking at nebulae and planets over the years, we had to
:27:25. > :27:31.get until 1982 for our first exo- planet, and here is why.
:27:31. > :27:36.To understand why it is so hard to find planets orbiting distant stars,
:27:36. > :27:43.you have to get a sense of how far those stars are from us here on
:27:43. > :27:47.earth. If I were to build a scale model of the galaxy in the Milky
:27:47. > :27:52.Way, starting here with the Solar System and this is the sun. Let's
:27:52. > :27:57.say I put the earth one centimeter away. If the earth were that big,
:27:57. > :28:02.the sun would be as big as this tea shop. Ignore that for a minute.
:28:02. > :28:06.Let's say this is the sun and I put the earth one centimeter away. That
:28:06. > :28:11.is known as one astronomical unit. To the outer planets of the Solar
:28:11. > :28:17.System, Neptune, that is 30 astronomical units, 30-times
:28:17. > :28:23.further away. On wards to the edge of the Solar System, there is the
:28:23. > :28:27.exo-planet, Pluto. That sits around 50 astronomical units away. We have
:28:27. > :28:31.about 50cms representing the size of our Solar System, out to Pluto.
:28:31. > :28:40.Now, on here somewhere, on a mountain, on the earth, in Hawaii,
:28:40. > :28:45.there is one of earth's most powerful telescope, the Keck
:28:45. > :28:51.telescope, it took a picture of Neptune and its moon. This is the
:28:51. > :28:55.most powerful photograph we have, and it is a featureless blob. At
:28:55. > :28:59.its further point from the sun, Pluto is 50 astronomical units away.
:28:59. > :29:07.That is nothing when you are building a model of the Milky Way.
:29:07. > :29:17.Because the nearest star to our sun is 268,000 astronomical units away.
:29:17. > :29:26.It is a star called Proximus Antori. I have to get much further out to
:29:26. > :29:32.mark its scale. If the earth is one centimeter away from the sun in the
:29:32. > :29:36.tea shop, then Proximus would be here, two kilo metres away, that is
:29:36. > :29:40.the nearest star. The telescope doesn't have trouble seeing it,
:29:40. > :29:47.although it is four light years away, it is 100-times the diameter
:29:47. > :29:53.of Pluto, and it is a star, a giant nuclear fusion reactor, giving out
:29:53. > :29:57.light. Imagine trying to see planet in orbit around Proximus Antori,
:29:57. > :30:02.they are smaller than a star, they don't give out light, and they
:30:02. > :30:09.reflect t they get lost in the glaer of the star. Trying to see a
:30:09. > :30:14.planet around Proximus Antori, would be like trying to see a grain
:30:14. > :30:18.of sand, 100 miles away, in the glare of a spotlight. Planets
:30:18. > :30:24.orbiting distant stars are so far away and difficult to detect, we
:30:24. > :30:28.discovered one for the first time, just 20 years ago.
:30:28. > :30:32.Far too distant to be seen by any telescope on earth, it was found by
:30:32. > :30:38.scientists who weren't looking for planets at all. They were looking
:30:38. > :30:44.for pulsars. Pulsars are neutron stars, the
:30:44. > :30:49.remains of dead stars. The leftovers of supernova explosions.
:30:49. > :30:54.They are incredibly small and dense. They can be the size of a city, but
:30:54. > :31:01.be more massive than the sun. They can spin very fast on their axis.
:31:01. > :31:05.When they do that, you get beams of intense radiation, a spinning
:31:05. > :31:11.around. Like a lighthouse beam. That lighthouse beam can cross the
:31:11. > :31:16.face of the earth. So we see a series of bright, regular pulses,
:31:16. > :31:20.and that is what gives them their name. The timing of the pulses is
:31:20. > :31:24.so precise, that they are as accurate and reliable as an atomic
:31:25. > :31:32.clock. But in 1992, scientists noticed something strange. One of
:31:32. > :31:35.the pulses missed a beat. It was as if the pulsar had wobbled. Our sun
:31:35. > :31:39.also wobbles as it spins on its axis. That is because it is
:31:39. > :31:45.surrounded by planets. The gravitational pull of the sun keeps
:31:45. > :31:49.the planets in orbit, but planets are also massive objects, they
:31:49. > :31:55.exert a gravitational pull on the sun. That causes it to worbl
:31:55. > :32:00.slightly. So -- wobble slightly. So scientists back in 1982, realised
:32:00. > :32:05.they were seeing the same thing happening to the pulsar, those
:32:05. > :32:09.precise rite Mick beams were being knocked out of -- rhythmic beams
:32:09. > :32:13.were being knocked out of sync slightly by the gravitational pull
:32:13. > :32:19.of the planet. The discovery proved there is a way to find planets too
:32:19. > :32:23.distant to be seen. They can be detected because they cause the
:32:24. > :32:29.stars they orbit around to wobble. Around three years after the first
:32:29. > :32:33.one was discovered, another worbl was discovered in the orbit of the
:32:33. > :32:43.Pegasus. It was not dead, it was a star like our sun. It was the
:32:43. > :32:44.
:32:44. > :32:48.unmistakable sign of a planet. They named it 51 Peg. The discover of 51
:32:49. > :32:54.Peg b was a watershed moment, it was the first time to find planet
:32:54. > :32:57.orbiting a living star, beyond our Solar System. Today we found over
:32:57. > :33:03.700 planets, fascinating in itself. But for me, the most interesting
:33:03. > :33:08.thing is it takes us closer to a far more precious goal, which is to
:33:08. > :33:17.discover an earth-like planet around a distant star, a planet
:33:17. > :33:22.that maybe could have life. So I can see why a wobble would be
:33:22. > :33:25.obvious in a pulsar, sending out these huge jets of radiation. A
:33:25. > :33:29.star like our sun doesn't do that, what is this wobble? The only thing
:33:29. > :33:34.you can do is look at the light. Stars do wobble. We have graphic
:33:34. > :33:39.here, which shows a star, and a planet. The star, which is here,
:33:39. > :33:43.looks as though it is orbiting as well, that is because it is. The
:33:43. > :33:46.star and the planet orbit around what is called the common centre of
:33:46. > :33:51.mass. The star will move a little bit. Think about the light that
:33:51. > :33:54.star is emitting, now if the star is coming towards us, then the wave
:33:54. > :33:59.lengths of that light become squashed, which means the light
:33:59. > :34:03.moves to the blue bit, the shorter wavelength of the spectrum. If the
:34:03. > :34:08.star is moving away from us, the light is stretched and the light
:34:08. > :34:12.shifts to us a long wavelength edge of the spectrum. That is called the
:34:12. > :34:16.Doppler shift, if you look at the spectrum of light from a star, and
:34:16. > :34:21.can you see if it is moving towards us and back, and towards us and
:34:21. > :34:26.back. By measuring that precisely you can infer there is a planet
:34:26. > :34:32.around it. That wobble can only occur if the planet is making a
:34:32. > :34:37.star? Really large planets so it is a substantial effect. The best
:34:37. > :34:41.technique for finding smaller more earth-like planets the transit
:34:41. > :34:45.method, which is what we have been using for our planet experiment
:34:45. > :34:50.over the last three nights? That looks for the dips in the light
:34:50. > :34:54.measures of distant stars. You can see it in the graphic, the planet
:34:54. > :35:00.crosses the face of the star, as seen from earth, and the light will
:35:00. > :35:04.drop as it leaves. 35 of the confirmed exo-planet discoveries
:35:04. > :35:09.came from Kepler, the planet hunting telescope, it is possible
:35:09. > :35:12.to search from earth. One of the best in the world is called
:35:12. > :35:18.SuperWASP. It is based in South Africa. Run remotely from Britain
:35:18. > :35:23.by scientists from Keele University. Believe it or not, by the push of a
:35:23. > :35:31.button. Liz is standing next to it. If we press this, that will kick
:35:31. > :35:39.off. There we go. How is that Liz? Good skills, Dara,
:35:39. > :35:42.don't let all that power go to your head now. This is SuperWASP. Super
:35:42. > :35:49.Wide Angle Search for Planets. When Dara isn't interfering with it, it
:35:49. > :35:53.is run remotely from Keele University in Staffordshire. One of
:35:53. > :36:00.their astronomers was in town earlier this week, giving it an MOT,
:36:00. > :36:05.I caught up with him to find out how this gorgeous machine works.
:36:05. > :36:11.So we have eight cameras here, each of which has an enormous field of
:36:11. > :36:15.view. It images 1% of the sky. looks like a fairly simple set-up,
:36:15. > :36:19.eight digital cameras, how do you go about finding exo-planets?
:36:19. > :36:22.monitor the same patch of sky, 50 times a night, we continue to do
:36:22. > :36:28.that for five months. At that point we have a measure of the brightness
:36:28. > :36:33.of the stars over time, and we look for periodic dimming that could be
:36:33. > :36:36.caused by a planet passing in front of the stars. We use bigger
:36:36. > :36:43.telescopes using another technique to confirm it is a planet. One in
:36:43. > :36:47.12 turn out to be so. How many exo- planets has SuperWASP found? 75 and
:36:47. > :36:51.counting. The planets we find, because they are easiest for us to
:36:51. > :36:56.find, are called hot Jupiter, planets around the size of Jupiter,
:36:56. > :37:05.much closer to their star than Jupiter. Which one interests you
:37:05. > :37:09.the most? One I'm fond of is WASP17b it is the first one in a
:37:09. > :37:14.retrogade orbit, it spipbs one way and the star the other way. It is
:37:14. > :37:19.counter to any planet known before and in the Solar System. It is
:37:19. > :37:27.discoveries such as these which is refining planet theories and
:37:27. > :37:32.evolution. With such confirmed exo- planets, what are the chances of
:37:32. > :37:35.one of them keeping life? The ones found are increasingly like our
:37:35. > :37:42.planet earth, I think the chances are very high. I think we will find
:37:42. > :37:45.life on another planet, within our lifetime.
:37:45. > :37:51.The reason why David isn't standing beside me right now for a bit more
:37:51. > :37:57.of a chat, is he's on his way to Chile right now to verify another
:37:57. > :38:02.bunch of exo-planets .5 confirmed exo-planets and counting, watch
:38:02. > :38:11.this space. 75 confirmed exo- planets and founding, watch this
:38:11. > :38:16.space. You saw the Lovell telescope being controlled by Dara and
:38:16. > :38:20.pointed towards Kepler 22b. Why have we done that? Kepler 22b is
:38:20. > :38:24.one of the best candidates for complex life outside the Solar
:38:24. > :38:27.System. As I said at the start, it is 600 light years away, a long way
:38:27. > :38:32.away. I don't think we will hear any signals from a civilisation.
:38:32. > :38:37.You never know. It has never been done before. I'm quite excited.
:38:37. > :38:40.number of our planets are in the region, we obviously are. Let me
:38:40. > :38:44.talk about the habitable region. There is a zone around any given
:38:44. > :38:48.star, around the sun it is the zone which the earth sits, but also
:38:48. > :38:53.Venus and Mars sit in that zone. It is the zone where roughly speaking
:38:53. > :38:56.the temperature will be right for things like liquid water and rich
:38:56. > :39:00.oxygen atmospheres to exist on planets. It is not a given that
:39:00. > :39:04.life will occur. Venus and Mars, there is no real evidence of any
:39:04. > :39:12.major complex life on those, eventhough they are in the hab
:39:12. > :39:15.table zone? Mars is too small, it is in the Habibi bittable zone, but,
:39:15. > :39:20.Venus has the hottest surface in the Solar System other than the sun.
:39:20. > :39:24.But Kepler 22b is in a similar zone around its star. Whilst you can't
:39:24. > :39:28.say for certain it is a habitable planet, it could be like Venus,
:39:28. > :39:33.Mars or none of the three. There is a chance that it is habitable. That
:39:33. > :39:39.means there is a chance that telescope is pointing at a
:39:39. > :39:45.civilisation of alien.S. Later in the show we will hear them.
:39:45. > :39:49.We will explain what the discovery could mean, and to tell us why it
:39:49. > :39:53.is so important is Giovanna Tinetti? It is a very exciting
:39:53. > :39:57.planet, Kepler 22b, it is orbiting a star very similar to the sun, it
:39:57. > :40:01.is the exact distance to the star to potentially have liquid water,
:40:01. > :40:05.that is why it is so interesting. What's the next step, how are we
:40:05. > :40:09.going to begin to characterise that planet and perhaps look for the
:40:09. > :40:15.signs of life? Essentially what we are doing right now with planets
:40:15. > :40:20.that are slightly hotter and bigger than Kepler 22b, is to use the
:40:20. > :40:24.method to look at their atmosphere, trying to get the composition of
:40:24. > :40:29.the atmosphere. We are looking at some light curves and preeting that
:40:29. > :40:34.at different wavelengths. You have to wait until the planet comes back
:40:34. > :40:40.around again and measure the light as it comes through the atmosphere?
:40:41. > :40:45.Exactly what a challenge, we can do it for other planets now. Is there
:40:45. > :40:50.a chance, Kepler 22b, is there a chance to map that planet out in
:40:50. > :40:53.detail? I'm afraid Kepler 22b is probably too far away to do this
:40:53. > :40:57.kind of measurement. We can certainly do this kind of
:40:57. > :41:02.measurement and planets around a starch closer to us, certainly we
:41:02. > :41:06.will do that with the dedicated space mission in the future, like
:41:06. > :41:12.Echo. As the light goes through it, what are the tell tale signs, what
:41:12. > :41:17.are you looking for? We look at the spectrum and look at the signature
:41:17. > :41:21.of some molecules, if you are interested, we are looking for
:41:21. > :41:28.molecule that is tell us something about if this planet is inhabited
:41:28. > :41:34.or not. I would love to see liquid water, or some water vapour, and in
:41:34. > :41:39.particular, having some signature or ozone or oxygen, like on earth,
:41:39. > :41:43.that would be an interesting signature. In earth's atmosphere,
:41:43. > :41:46.oxygen is only present because of the action of life in large
:41:46. > :41:50.quantities, if you saw that in one of these planets, you would be
:41:50. > :41:54.fairly certain there is life. We have to go back to Dulverton now,
:41:54. > :41:59.I'm afraid. They have had 20 minutes to get used to the dark.
:41:59. > :42:06.Usually in astronomy it takes 20 minutes for your eyes to
:42:06. > :42:10.acclimatise. We will go back to see how different the place feels. That
:42:10. > :42:14.was nothing more than amazing. To see the lights go out. Every single
:42:14. > :42:17.light that I could see in the Main Street has gone out. It went so
:42:18. > :42:23.dark. It has taken our eyes a little bit of time to adjust. It is
:42:23. > :42:27.like being in the countryside but in the middle of a town. Joining me
:42:27. > :42:31.is a local astronomer. What is it like having all the lights out?
:42:31. > :42:35.is very much like how it was when I was younger. I could come out and
:42:35. > :42:38.see the great ribbon of stars in the Milky Way, now all the fainter
:42:38. > :42:42.stars have gone. It is a chance to get that back again. If it was
:42:42. > :42:47.clear it would have been lovely? would have been glorious. It is
:42:47. > :42:51.great to see the way it has worked. We're joined bit headmaster of the
:42:51. > :42:54.local school. The entire community has come together for this? They
:42:54. > :42:57.have, it really has company turd the imagination of the communety.
:42:58. > :43:04.You only -- captured the imagination of the community. You
:43:04. > :43:08.only go walk down the street and see the effort the shopkeepers have
:43:08. > :43:12.made. Hopefully it is the start of something and we get left with a
:43:12. > :43:17.legacy we have already been talking about forming a local astronomical
:43:17. > :43:21.society, and having a sunnor branch based at the schools. That is in--
:43:21. > :43:25.A junior branch based at the schools. This has shown tonight,
:43:25. > :43:29.regardless of the fact we can't see clear stars, everyone can take
:43:29. > :43:34.responsibility for light f we can do that and think how we are using
:43:34. > :43:39.it we can make a difference. If you want to learn more go to the
:43:39. > :43:43.website. You can find a link to the dark skies discovery network on
:43:43. > :43:51.stargazing@bbc.co.uk. You can find out where the local
:43:51. > :43:55.dark spots are and recommend your own dark sites.
:43:55. > :43:59.I have to say, I'm just the messenger, not the person who
:43:59. > :44:02.brings the weather, one night this week we really needed those clear
:44:02. > :44:05.week we really needed those clear skies. At Dulverton the rain has
:44:05. > :44:10.moved in, the same across many parts of central, southern England
:44:10. > :44:14.and Wales overnight. The best chance to get the telescope out,
:44:14. > :44:18.eastern England, Northern Ireland, Scotland. Cloud will vair year, but
:44:18. > :44:21.lengthy clearer spells, even clearer spells across parts of
:44:21. > :44:24.western Scotland. Tonight, clearer spells in the north, tomorrow we
:44:24. > :44:28.might reverse it a little bit. Scattering of showers expected.
:44:28. > :44:32.These will be mainly to northern and western areas. Some of those
:44:32. > :44:36.will be wintry. Eastern Scotland, north-east England, get out early
:44:36. > :44:41.on before the cloud thickens up. For much of England aWales, away
:44:42. > :44:44.from the north and west, a few hours before the cloud pushes in.
:44:44. > :44:49.Into the weekend, whilst seeing plenty of showers, across eastern
:44:49. > :44:53.and southern parts, the air will be fairly clear at times. A cold air
:44:53. > :44:57.mass coming down from the north, the clarity of the air should
:44:57. > :45:01.the clarity of the air should increase as well. Happy stargazing.
:45:01. > :45:06.I thought that showed the real spirit of stargazing, eventhough it
:45:06. > :45:12.is cloudy in Dulverton, even the act of making it dark, the school
:45:12. > :45:18.will be getting involved and the astronomical Society being formed,
:45:18. > :45:21.and the schools getting involved. Try it every night of the year! We
:45:21. > :45:26.set the dish moving at the beginning of the show, we now have
:45:26. > :45:32.a unique chance to listen to the radio waives coming from an exo-
:45:32. > :45:36.planet, Kepler 22b. What should we listen out for? We should listen to
:45:36. > :45:43.what the Hubble Space Telescope usually hears, the radio waves
:45:43. > :45:50.created into sound. This is space noise. It sounds like empty static.
:45:50. > :45:54.That is just radio astronomy, there is data in there. Listen to this.
:45:54. > :45:57.(knocking) If you heard that, would you think that's regular, that is
:45:57. > :46:01.not natural. In fact, that is natural. That is the sound of a
:46:01. > :46:08.pulsar. When it was first heard, the first pulsar was discovered,
:46:08. > :46:12.that was named LGM1 that means "little green men 1". For a few
:46:12. > :46:18.days it was thought how can something from nature be so regular.
:46:18. > :46:23.If we hear that from Kepler 22b, it is a pulsar. If we hear a regular
:46:23. > :46:25.beat like that, we would have to postpone the news. There is only
:46:25. > :46:31.one incident where something was heard that couldn't be explained.
:46:31. > :46:35.It is called the WOW signal. It is a picture of it. That is the
:46:35. > :46:42.picture of the data from a radio telescope a regular strange signal
:46:42. > :46:45.was heard, to this day it hasn't been explained. It is called WOW,
:46:45. > :46:49.because the radio operator wrote that next to it. They have gone
:46:49. > :46:53.back to the skies, and nothing has been heard since. It remains
:46:53. > :46:57.genuinely unexplained. Tim comes back in, if we do hear
:46:57. > :47:03.something you would really want to be here? Certainly. I have my
:47:03. > :47:07.fingers crossed. Do we think we will hear anything? Tim it is
:47:07. > :47:11.probably too far away even if it was a noisy civilisation. If they
:47:11. > :47:20.put a beacon there. A strong enough transmitter and telescope, you
:47:20. > :47:24.never know. This is the sound coming to us live from Kepler 22b.
:47:24. > :47:29.(static noise) That is quiet you have now. It is quiet, that is what
:47:29. > :47:33.we expected, of course. Tim, it sounds like a game, it sounds like
:47:33. > :47:38.science fiction. It isn't, there is the SETI project, which this
:47:38. > :47:41.telescope has been involved in, searching for signals. It is a
:47:41. > :47:45.serious possibility, if you don't look you won't find anything. It is
:47:45. > :47:55.worth having a look and listen in this case and analysing the signals
:47:55. > :47:58.very carefully, just in case. search for exo-planets, now we can
:47:58. > :48:05.focus where we look for possible civilisations. We may be closer
:48:05. > :48:08.than ever to finding a planet with life, but the idea of attempting to
:48:08. > :48:18.communicate with civilisations in the distance is not new. What would
:48:18. > :48:20.
:48:20. > :48:30.it mean to make first contact? It is easy to find the idea of UFOs
:48:30. > :48:31.
:48:31. > :48:38.and extraterrestrial life a bit of But for centuries scientists have
:48:38. > :48:40.taken the idea of alien contact very seriously. Early astronomy
:48:40. > :48:44.revealed our Solar System contained other planets, and as soon as we
:48:44. > :48:48.thought there could be worlds like our's nearby. We couldn't wait to
:48:48. > :48:53.tell them that we were here. We were sentient and we were dying to
:48:53. > :48:57.say hello. If you look certainly at the 19th century, there was some
:48:57. > :49:02.quite prominent scientific figures who had really quite practical
:49:02. > :49:09.ideas for how you might try to communicate with alien life. So,
:49:09. > :49:15.for example, Carl Friedrich Gauss, a very famous mathematition and
:49:15. > :49:22.scientist, had an idea for cutting enormous geomet kal shapes into the
:49:22. > :49:25.Siberian forest which would be -- geomet kal shapes into the Siberian
:49:25. > :49:30.forest which would be seen from space.
:49:30. > :49:40.He felt strongly that the sun might be a habitable place, and it might
:49:40. > :49:48.
:49:48. > :49:53.be worth looking for life forms we could communicate on the sun.
:49:53. > :49:59.As astronomy became clear, it was thought that aliens had to be out
:49:59. > :50:05.joyed suer Solar System. Science had to develop enormously before
:50:05. > :50:11.messages could be sent out to other worlds. In the 1970s NASA launched
:50:11. > :50:15.the Pioneer and Voyager probes, sent to look at the outer Solar
:50:15. > :50:20.System. In case they came across aliens, on board they carried
:50:20. > :50:24.information about us. Pioneer contains a plaque which has
:50:24. > :50:28.on it the location of the Solar System, some basic scientific
:50:28. > :50:33.information, and most famously a picture of two naked human beings,
:50:33. > :50:38.generally thought to be average Americans, in mellow greeting. You
:50:38. > :50:42.know the way average Americans are this buff and hairless. At the time
:50:42. > :50:46.of the Voyager launch, more information could be encoded,
:50:46. > :50:50.including an entire disc of sounds of the earth, more scientific
:50:50. > :50:58.information, and images of our history and culture. Whether of
:50:58. > :51:03.hunting, the moment of conception, and that guy. Images of licking,
:51:03. > :51:06.biting and swallowing, as some sort of threat, presumably. To counter
:51:06. > :51:16.act that, we also included greetings recorded from people from
:51:16. > :51:22.
:51:22. > :51:27.all over the world, in their own However, these messages would be
:51:27. > :51:33.very difficult for any alien life form to find. Although the Voyager
:51:33. > :51:38.I probe is now the fastest and distant human-made object in the
:51:38. > :51:41.universe, it is still comparatively nearby, inconspicuous and slow.
:51:42. > :51:46.Creatures from other worlds would literally have to bump into it in
:51:46. > :51:51.order to retrieve the message. It won't even reach the nearest star
:51:51. > :51:58.system for another 40,000 years. But there was another way in which
:51:58. > :52:02.we could search for alien life, radio waves. In 1960, visionary
:52:02. > :52:05.astronomer, Frank Drake, made the first deliberate attempt to detect
:52:05. > :52:09.signals from other world. Scientists from around the world
:52:09. > :52:15.soon joined the search, which became known asset at this, the
:52:15. > :52:20.search for extra terrestrial intelligence. It dawned on radio
:52:20. > :52:24.astronomers in the 1950s that these big radio telescopes can be
:52:24. > :52:28.limitless in size. They are capable of enormous sensitivity. They
:52:28. > :52:33.communicate not just across terrestrial distances or
:52:33. > :52:37.interplanetary distances, but truly interstellar distances. The fact we
:52:37. > :52:43.can search for messages throws up another question, what do we do if
:52:43. > :52:48.we find one? And what if by sending a message we attract the attention
:52:48. > :52:52.of great big extraterrestrial monsters who want to eat us. Even
:52:52. > :52:58.if their intentions are benign, we could be opening ourselves up to
:52:58. > :53:03.unexpected dangers. Afterall, our own history of encountering foreign
:53:03. > :53:08.culture offers a cautionary tale. Very often they started like
:53:08. > :53:14.Captain Cook arriving in Hawaii, with best intentions, handshakes
:53:14. > :53:18.and smiles wall the way round. But Captain Cook still didn't survive
:53:18. > :53:25.the encounter. Despite all the friendship and treaties, within 150
:53:25. > :53:30.years, 90% of people in Hawaii were dead, because of diseases that were
:53:30. > :53:35.unintentionally introduced. Even when things are all shand shake and
:53:35. > :53:40.-- handshake and friendly there can be terrible consequences. None the
:53:40. > :53:46.less, the SETI post detection task group is standing by, should an
:53:46. > :53:50.alien signal arrive. Professor Paul Davies could be among the first to
:53:50. > :53:53.receive a message from ET, his response might not use words at all.
:53:53. > :53:58.The things we would truly share are the things that are literally
:53:58. > :54:02.universal throughout the universe, that is mathematics and fistics,
:54:02. > :54:08.the laws of physics are the same throughout the universe, and
:54:08. > :54:12.mathematics are the same throughout by that definition. One could build
:54:12. > :54:16.a broader dialogue, and after thousands of messages back and
:54:16. > :54:21.forth we could tell them about our politics and sport. We can hope
:54:21. > :54:24.that their politics and sport doesn't include eating us! The
:54:24. > :54:29.truth is, whatever the price, receiving an alien message will
:54:29. > :54:36.confirm what some of us are desperate to know, that we aren't
:54:36. > :54:44.alone in the universe. Three nights ago we asked you to do
:54:44. > :54:47.something very special, we wanted you to help us find a Stargazing
:54:47. > :54:51.exo-planet. Chris Lintott is in charge. Have we found planet?
:54:51. > :54:56.have, we think we have. We were looking for the dips in light in
:54:56. > :55:01.the stars' brightness when planets get in front of the parent star. We
:55:01. > :55:06.found one in particular that two people told us they were the dips,
:55:06. > :55:09.we went back into the data and found five of the tips, each 90
:55:09. > :55:15.days apart. We think it is planet that goes around this particular
:55:15. > :55:20.star once every 90 days. How many people responded? Over 100,000
:55:20. > :55:23.people, well over a million classifications, one million and
:55:23. > :55:29.84,000 classifications. These are ordinary people, watchers of
:55:29. > :55:35.Stargazing? They went to the website, the PlanetHunters, lock
:55:35. > :55:42.logged on and -- logged on and did what people are still doing now
:55:42. > :55:47.Let's see the data. I want to name it. This is Lee
:55:47. > :55:51.Threplton, and then Chris Holmes, on the right, later on, that is 90
:55:51. > :55:55.days later. We are looking at the light from the star, characteristic
:55:55. > :55:59.dip of the planet crossing the face of the star. If you look to 90 days
:55:59. > :56:09.after, that we dug into the computer. It should be noted there
:56:09. > :56:10.
:56:10. > :56:11.were others who spotted these planets they were after Threpl to n
:56:11. > :56:14.and Holmes. Those names down the bottom of the screen have
:56:14. > :56:18.identified it and others too. is lots more we have got there.
:56:18. > :56:24.More data we are put anything right now. If anyone else wants a planet
:56:24. > :56:30.named after them they can go there. We have an artist's impression of
:56:30. > :56:36.the planet. It is Neptune-sized. It is gaseous, it is a hot Neptune, it
:56:36. > :56:46.goes around its star in 90 days, as close to the star as Mercury.
:56:46. > :56:46.
:56:46. > :56:51.is the planet we are unofficially and bindingly calling planet
:56:51. > :56:59.Threplton-Holmesb. Where is it? outside now, stair ten degrees in
:56:59. > :57:05.the North West, between Deneb and deep Veg a. You need a pretty big
:57:05. > :57:09.telescope but they found it on-line, but they found it. It is gas planet,
:57:09. > :57:12.we wouldn't necessarily find life? It is too hot, it is in The Golden
:57:12. > :57:19.Calf zone t might have a moon, you withstand on one of the moons and
:57:19. > :57:25.look at the wonder that is Threplton-Holmes. Thank you, this
:57:25. > :57:29.is incredible for me, our audience has found a new planet around a
:57:29. > :57:34.distant star. And named after two guys we have never met. What an
:57:34. > :57:39.amazing way to bring the programme to a close. Goodbye to Liz in South
:57:39. > :57:43.Africa, we found a planet Liz, can you believe that? That is such
:57:43. > :57:47.brilliant news. Isn't it astounding what we can achieve in this day and
:57:47. > :57:50.age. I know we have had cloudy skies the last three nights t has
:57:50. > :57:55.been a privilege to be here and learn about the skies in the
:57:55. > :57:58.company of hugely inspirational astronomers, a big thank you to
:57:59. > :58:03.them, they have been wonderful. Armed with the telescopes they are
:58:03. > :58:07.helping us take huge leaps in our understanding of the universe,
:58:07. > :58:09.especially in the hot topic of exo- planets. They are revealing how
:58:10. > :58:14.much there is left to learn about the universe, not just in deep
:58:14. > :58:18.space, but also within our very own solar siste. It is really a very
:58:18. > :58:22.exciting time to be an -- system. It is really a very exciting time
:58:22. > :58:28.to be an astronomer. That is all from the team in South Africa, back
:58:28. > :58:32.to you at Jodrell Bank Observatory. That is a glorious sky, finally
:58:32. > :58:36.seeing a good sky over South Africa. Stay with us for Back To Earth,
:58:36. > :58:45.coming up immediately afterwards. We have many questions to raise
:58:45. > :58:52.about the inhabitants of Threpleton-Holmes. There is warring
:58:52. > :59:02.factions I'm sure. There is more information on the website. Find
:59:02. > :59:03.