:00:27. > :00:30.Welcome Back To Earth, a chance to explore some issues, shows some
:00:30. > :00:35.photographs and give a sense of what it is like working on the show.
:00:35. > :00:38.We thought we would make this little film. I am here by the
:00:38. > :00:42.Lovell telescope at Jodrell Bank and at the start of each day before
:00:42. > :00:50.every show, I like to come out here and make sure everything is working
:00:50. > :00:56.like it should be. Yeah, all good. Come with me, as I take you on an
:00:56. > :01:00.exclusive behind-the-scenes tour of Stargazing Live. It is from here
:01:00. > :01:04.that the movements of that amazing dish behind they are precisely
:01:04. > :01:07.monitored. My favourite bit is all these buttons, there's loads of
:01:07. > :01:11.buttons and you want to go like that and press them all, but you
:01:11. > :01:18.are not allowed to do that. You would get done if you were to do
:01:18. > :01:26.that, so I am not doing it. This is a room that is full of tellies, and
:01:26. > :01:30.pretty soon, I'm going to be on all of them. Having that. One of the
:01:30. > :01:35.wonders of lunchtime is when I do some shopping and get some things
:01:36. > :01:41.to recreate the diversity of our solar system. Like Mercury would be
:01:41. > :01:46.a tick tack, just by the sun. You have got Venus and are worth. And
:01:47. > :01:51.next to them, Mars, a Maltese have. Jupiter is this watermelon. You
:01:51. > :01:57.have the asteroid belt, which we are going to recreate with a bag of
:01:57. > :02:03.rivals like that. Some hundreds of thousands, that is the galaxy. And
:02:04. > :02:09.that is why I love lunchtime. Astronomy allows us to contemplate
:02:09. > :02:12.profound and very big things. The depth of the universe will see its
:02:12. > :02:20.gradual dissipation and ultimate demise, but the number of years
:02:20. > :02:28.until this happens is a huge number. So huge, I need help to express it,
:02:28. > :02:35.because it is 10,000 billion, billion. Billion. Billion. Billion.
:02:35. > :02:45.Billion years. That is like loads. Cheers.
:02:45. > :02:46.
:02:46. > :02:51.I said, the only imperfection in his impression is that his hair is
:02:52. > :02:58.not cry enough. He needs to get a Cryer wig. You look like you, and
:02:58. > :03:06.you look like the bass guitar as from a Beatles tribute band. It is
:03:06. > :03:11.not a good look for you. Thank you for joining us. We have our experts,
:03:11. > :03:16.Tim O'Brien is with us, Dr Lucy Green, Dr Andrew Pontzen, we met
:03:16. > :03:21.briefly and did not get rid of you and we said goodbye, apologies.
:03:21. > :03:27.Thank you for coming back, it is very kind. We always give somebody
:03:27. > :03:31.a gift, you deserve it more than anybody. This is meteorite wine. It
:03:32. > :03:41.is Chilean, feel free to pop the cork. During the ageing process,
:03:41. > :03:49.they place a meatier into the cask. As Patrick Moore says, have a drink.
:03:50. > :03:56.How has it been out in the cold? Talk amongst yourselves! They claim
:03:56. > :04:04.it is like tasting the birth of the universe. Are you going to give it
:04:05. > :04:09.a taste? I certainly am. Who is coldest? I am not entirely
:04:09. > :04:14.convinced. You are an added astronomer. As it helped to have a
:04:15. > :04:18.few experts around -- Abid astronomer? It is always a great
:04:18. > :04:26.thing to get a great group of astronomers together and everybody
:04:26. > :04:34.helps each other out. There is quite a nice communal field.
:04:34. > :04:38.seems like a happy group of people. I haven't got wind, somehow. Am I
:04:38. > :04:43.supposed to drink from the bottle? How lousy does this look? It seems
:04:43. > :04:49.like a good time to go to a question from a 12-year-old. Great
:04:49. > :04:58.question, 12-year-old! Sorry. It is from Alex Worthington. The question
:04:58. > :05:03.is, could a black hole one day appear near Earth and suck us in?
:05:03. > :05:08.No, it won't suck us in. Yes, they could appear. There is a theory
:05:08. > :05:13.that there are things called primordial black holes, very small,
:05:13. > :05:16.atomic black holes. It could have been around -- they could have been
:05:16. > :05:20.around since the Big Bang. They could be small black holes around
:05:20. > :05:22.now, floating through this room, and we would not know it. How long
:05:23. > :05:28.would it take for them to develop into something bigger and more
:05:28. > :05:33.dangerous? They won't. Just because it collapses and it is a black hole,
:05:34. > :05:38.if the sun became a black hole... It would be about three kilometres.
:05:38. > :05:42.You could squash it down and you would not notice, the earth would
:05:42. > :05:46.continue to orbit around it. It is a misnomer that they give up
:05:46. > :05:50.everything that is around them. the sun turned into a black hole,
:05:50. > :05:57.it would get dark in eight minutes, we would get very cold and all die,
:05:57. > :06:01.but we would not get sucked into it! So look on the bright side!
:06:01. > :06:04.Tiny black holes also evaporate very quickly, it is faster for the
:06:04. > :06:13.small black holes and the big black holes. By quickly, what do you
:06:13. > :06:18.mean? You're putting me on the spot. Talking about fractions of a second.
:06:18. > :06:23.People are talking about CERN creating black holes. They were mad
:06:23. > :06:28.people! They are already watching ITV, or Big Brother. He drives them
:06:28. > :06:34.a way! It is not mad that it could create black holes, but they would
:06:34. > :06:38.evaporate very quickly. The sun is not going to become a black hole?
:06:38. > :06:42.It is not massive enough, you need to be several times the mass of the
:06:42. > :06:48.Sun to be able to end the days of the start collapsing down, with
:06:48. > :06:58.gravity unable to stop the collapse. It would die in a much calmer, more
:06:58. > :07:00.
:07:00. > :07:04.sedate way. Heather asks, are black holes like wormholes in Star Trek?
:07:04. > :07:09.There is Solutions of Einstein's equations which have that property.
:07:09. > :07:16.I think they have to spin. I think we don't know, is probably the
:07:16. > :07:21.answer. There has been no evidence for them. We are not certain that
:07:21. > :07:27.they really do exist? You hear them a lot in science fiction. They
:07:27. > :07:30.might do. I don't think it is clear. If you have something that is
:07:30. > :07:34.formed in the real universe from a star collapsing. Under those
:07:34. > :07:40.circumstances, it seems unlikely you would end up with a 1 hole. It
:07:40. > :07:47.is more like mathematical solutions which have these wormholes. Can we
:07:47. > :07:57.get to Skype? I think we can get to Henry, he is six, with his mum.
:07:57. > :08:00.
:08:00. > :08:07.Hello. What question have you got? What would happen if the sun went
:08:07. > :08:09.to a black hole, and how do black holes what? Thank you. Nice work.
:08:09. > :08:13.It is a brilliant question. We already spoke about what would
:08:13. > :08:17.happen, nothing would happen, except it would go dark and we
:08:17. > :08:21.would eventually get very cold. But the Earth and the solar system
:08:21. > :08:26.would remain the same. But how do black holes work is a fascinating
:08:26. > :08:32.question. The answer is that we don't know. Do you have anything to
:08:32. > :08:36.add? I think the thing about explaining why we would not get
:08:36. > :08:40.sucked into a black hole is, if you could get a giant pair of hands and
:08:40. > :08:46.crush the Sandown, it would turn into a black hole but it's a mass
:08:46. > :08:51.would not change -- the sound down. Its mass determines how we orbit
:08:51. > :08:57.around it. We would not notice if the sun turned into a black hole, I
:08:57. > :09:01.guess. There was a science-fiction idea that you could use the pull of
:09:01. > :09:10.a black hole and Emmett waste into it, and that would turn the well
:09:10. > :09:15.that it was on. Is there any way of harnessing something like that?
:09:15. > :09:18.is not obvious. Technologically, it seems pretty unlikely. But we see
:09:18. > :09:23.in the universe, black holes are an amazingly efficient way of its
:09:23. > :09:32.generating energy, more efficient than stars. If you chuck some mass
:09:32. > :09:39.into a black hole, something like 10% of E=MC squared comes back.
:09:39. > :09:45.That is from the radiation that we see. Matt asks, what is the largest
:09:45. > :09:50.black hole that we know of anywhere. There are several billions of times
:09:50. > :09:58.the mass of the Sun. The Super massive black holes that we talk
:09:58. > :10:06.about. There are ones which are like the sun collapsing, are the
:10:06. > :10:11.Super massive black colts much greater than the... Many times
:10:11. > :10:21.greater, you have to happen to have much more material coming in, which
:10:21. > :10:22.
:10:22. > :10:26.is why you see them at the centre of galaxies. Do they begin as a
:10:26. > :10:31.super massive black holes? We have an idea of how they originate but
:10:31. > :10:35.they tend to be relatively small solar mass type black holes, it is
:10:35. > :10:41.pretty hard to see how you get from there to super massive black holes.
:10:41. > :10:46.Once you have the super massive million solar mass because, you can
:10:46. > :10:51.merge those and carry on making bigger ones. But it is hard.
:10:51. > :10:56.heard Event Horizon used. What is that? What is the difference
:10:56. > :11:01.between that and singularity. singularity is the mathematical
:11:01. > :11:07.description of what a black hole is. That is what the equations tell you
:11:07. > :11:12.you get. Considering how close you have to get to be sucked in, coming
:11:12. > :11:16.back to this idea that black holes are cosmic Hoovers, if the sun
:11:16. > :11:20.turned into a black hole, you would not get sucked in. But you would,
:11:20. > :11:24.if you got to the event horizon. That is the distance at which there
:11:24. > :11:29.is the point of no return. As you get closer to an object, the
:11:29. > :11:38.gravitational pull increases. When you get to the event horizon...
:11:38. > :11:42.have to interrupt. We are getting loads of photographs. We are going
:11:42. > :11:50.over to marker. This is a representation not to
:11:50. > :11:57.scale, I hasten to add, of the observable universe you have been
:11:57. > :12:07.sending in fantastic pictures. We have some quite incredible ones. I
:12:07. > :12:13.
:12:13. > :12:23.start with a picture by Robert He took this using a five-inch
:12:23. > :12:34.
:12:34. > :12:40.It is a really superb image. The second image was taken at the role
:12:40. > :12:47.right stones, which we used in our light permission film -- pollution
:12:47. > :12:56.from. The camera is pointed at the sky and allows the stars to trail
:12:56. > :13:04.across the camera. This is my favourite picture, of the sun with
:13:04. > :13:08.a jet aircraft passing just in front. It was taken with a solar
:13:08. > :13:18.telescope, which means you can get a very good clear image of the Sun,
:13:18. > :13:24.
:13:24. > :13:29.Apparently we are getting nothing but the mouse questioning your
:13:29. > :13:36.hardline stance to UFOs. There is something on the Fermi Paradox
:13:36. > :13:42.which his 4th ball and powerful. -- -- which is a thoughtful. The
:13:42. > :13:48.question is, why are they not here? The reason is, the galaxy is sold,
:13:48. > :13:52.there are so many star systems, that is it is difficult to
:13:52. > :13:58.understand why there is not a civilisation somewhere that is more
:13:58. > :14:02.advanced, such as it should have colonise the galaxy. There is
:14:02. > :14:06.nothing in the law of physics that says, give us a million years and
:14:06. > :14:15.we should have been able to explore the galaxy. The question is, why
:14:15. > :14:20.don't we see these alien probes? It is difficult to explain why. My
:14:20. > :14:26.stance... I would not be surprised at all if a UFO landed over there.
:14:26. > :14:30.However... On people having fun and enjoying themselves... I think they
:14:30. > :14:39.are going to appear or they are not. If they want to come and be seen,
:14:39. > :14:43.If they want to hide, they will not mess it up a bit. They were not
:14:43. > :14:49.abduct 150,000 American farmers, failed to wipe the memory and then
:14:49. > :14:59.they write a book and become famous. They would not mess up in that way.
:14:59. > :15:01.
:15:01. > :15:04.I think that aliens might be gently watching us in the same way that
:15:05. > :15:12.David Attenborough observes penguins. I like the assumption
:15:12. > :15:16.that the penguins do not observe David Attenborough. I don't think
:15:16. > :15:21.the penguins stick sticks into David Attenborough. Moving on to
:15:21. > :15:26.celestial matters. You can drink as I am asking. Do you think there
:15:26. > :15:30.will be a time when we can see black holes? Yes, I think this is a
:15:30. > :15:33.really interesting question. I think there may well be. There are
:15:33. > :15:37.lots of simulations done at the moment to give us an understanding
:15:37. > :15:42.of what we need to look for in order to be able to see these
:15:42. > :15:48.invisible object. You can see a mission from hot material that
:15:48. > :15:54.forms the disco around them. But if you seek no hot material, what are
:15:54. > :15:57.you looking for? A black shadow against the starry background. The
:15:57. > :16:00.simulations have shown us the distortions in the distribution of
:16:00. > :16:05.stars because of the effect of the black hole. Even if the black hole
:16:05. > :16:11.is spinning, the black shadow would change its shape and get distorted.
:16:11. > :16:16.Theoretically we understand some of what we should be looking for,
:16:16. > :16:23.should we get telescopes that are good enough. There is a meeting
:16:23. > :16:28.tomorrow in the States that is to discuss the event horizon telescope.
:16:28. > :16:31.They are looking at a network of 50 telescopes spread across the whole
:16:31. > :16:39.planet, working together, the King at the black hole at the centre of
:16:39. > :16:45.the Milky Way that we discussed earlier. -- looking at. We will be
:16:45. > :16:54.looking at light wavelengths of about 1 mm. They hope to see the
:16:54. > :16:58.shadow and directly see the black hole. We think that black holes
:16:58. > :17:08.Bennett something, and if that is true then they can evaporate away.
:17:08. > :17:09.
:17:09. > :17:15.There is a stream of particles. Could we be sense -- sensitive
:17:15. > :17:19.enough to see that? I think the ones that live for very long time
:17:20. > :17:23.scales are very cold. When they get smaller, they emit radiation and
:17:23. > :17:31.they lose mass, they get smaller, and that process accelerated and
:17:31. > :17:34.they get hotter and hotter. I am not sure. It is unlikely that we
:17:34. > :17:36.could detect radiation from anything Astrophysical but
:17:36. > :17:43.something that is really interesting is gravitational wave
:17:43. > :17:46.detection. One way of detecting black holes is that when they are
:17:46. > :17:54.emerging they emit gravitational waves and there are projects to try
:17:54. > :17:59.it and detect them. Yes, we are looking for those ripples that
:17:59. > :18:02.would spread through the university. There would be two masses around it
:18:02. > :18:05.which could collide into one big black hole and that could happen in
:18:05. > :18:10.the next 10 years. Could there be the faintest possibility that if
:18:10. > :18:17.you pass through a black hole, wormhole, is somehow the men
:18:17. > :18:25.yourself into another dimension, another time? -- used somehow e-
:18:25. > :18:28.mailed yourself. If you look at a messy, collapsing star, complicated
:18:28. > :18:32.astrophysics means that these nice, mathematical properties go away and
:18:32. > :18:36.I honestly don't think we know what an astrophysical black hole is
:18:36. > :18:42.really like. On the subject of science fiction and science fact,
:18:42. > :18:47.that is the perfect point to go to Patrick Moore with that question.
:18:47. > :18:56.Science fact or science-fiction? Look at this remarkable picture. It
:18:56. > :19:01.is aerogel. Has aerogel ever been used in space? Science fact or
:19:01. > :19:06.science-fiction? OK, the question he was asking was about aerogel.
:19:06. > :19:10.Are you familiar with that? I am not going to say anything. I am
:19:10. > :19:15.familiar with it. It has been used in space missions, as he said. It
:19:15. > :19:19.can be used as a particle detector to detect radiation, where
:19:19. > :19:29.particles can pass through the aerogel faster than light. What
:19:29. > :19:33.
:19:33. > :19:39.exactly is it? Highly dangerous? Lovely. I have heard it described
:19:39. > :19:49.as liquid smoke. It breaks open very easily. Very expensive. Is it
:19:49. > :19:56.important? That is really cool. That is the other half. Would you
:19:56. > :20:01.like to look? Has it been used in space? You have sort of answered
:20:01. > :20:09.that question. Have I done it again? You have. It is science fact.
:20:09. > :20:15.Is that right? Yes, this time you are right. Aerogel has been used in
:20:15. > :20:20.space to cap to cosmic dust. It is so incredibly low density that it
:20:20. > :20:30.picks it up. There is nothing else quite like it.
:20:30. > :20:30.
:20:30. > :20:34.Aero gel is an incredibly low density foam and its shares for one
:20:34. > :20:44.trait with my hand. It is hydrophobic so that because water
:20:44. > :20:46.
:20:47. > :20:56.and your hand should not get wet. - - repels water. That is bizarre. It
:20:56. > :21:04.is absolutely dry. Do It again! This is amazing. It is completely
:21:04. > :21:08.impossible to wash off or remove. My hand goes into water. You cannot
:21:08. > :21:18.feel any water. You can feel the temperature but not the winners.
:21:18. > :21:19.
:21:19. > :21:23.And it comes out completely dry. That is how James Bond does it!
:21:23. > :21:28.had does feel very weird. I have a feeling this stuff will be on me
:21:28. > :21:34.forever in some shape or form. I must make a mental note not to go
:21:34. > :21:37.to the toilet immediately after the show. If large matters are drawn to
:21:37. > :21:41.one another, does that mean that black holes will eventually swallow
:21:41. > :21:44.everything up? I suppose theoretically if things got close
:21:44. > :21:49.enough to a black hole, then they could. But they don't keep on
:21:49. > :21:55.expanding. Over time do they get larger or smaller? Event Horizon
:21:55. > :21:59.will get larger if you have more material going into it. In the very
:21:59. > :22:03.long term, but the evolution of the universe will be overtaken by dark
:22:03. > :22:08.energy, or at least we think so. We don't really understand it. That
:22:08. > :22:16.will push all of the Delic is in the universe further apart. If for
:22:16. > :22:21.of the material can fall into the black holes, then they will be
:22:21. > :22:26.further and further apart and there will be lots of time to radiate
:22:26. > :22:29.radiation and evaporate. If they stop eating, they evaporate?
:22:29. > :22:33.Presumably the scales between different galaxies are sufficient
:22:33. > :22:40.that they will not heat up? Andrew is right. Things are not close
:22:40. > :22:44.enough in the universe to come together but the erratic laid... --
:22:44. > :22:48.theoretically... You have heard the boundaries of physics expressed
:22:48. > :22:52.beautifully. We have no idea what dark energy is, it is fair to say.
:22:52. > :22:57.It looks like 70% of the universe is taken up making the universe
:22:57. > :23:01.expand more quickly, accelerating its expansion. It is an absolute
:23:01. > :23:05.mystery. Black holes are a mystery. We are talking about this radiation
:23:05. > :23:12.as though it is the fat. It is well established theoretically but we do
:23:12. > :23:16.not know if black holes will evaporate. Do we know how we can
:23:16. > :23:19.interact with black holes? I will pass dark energy on to the
:23:19. > :23:23.cosmologists, but dark matter is potentially in the realm of
:23:23. > :23:28.particle physics. The Large Hadron Collider might make super separate
:23:28. > :23:31.particles, a whole new set, like a mirror world if you like, but
:23:31. > :23:35.heavier than these particles. The light is one of those is predicted
:23:35. > :23:39.to be stable and it is a candidate for dark matter. It could be that
:23:39. > :23:44.the universe is full of super symmetric particles. We may
:23:44. > :23:48.discover those in the coming years. Dark energy? It only behaves like
:23:48. > :23:52.anti-gravity. It was a complete shock when it was discovered in
:23:52. > :23:55.1998. We have been looking at the universe expanding and what we were
:23:55. > :23:59.expecting was these galaxies being pulled back together by their
:23:59. > :24:03.gravity. Then the expansion would be slowing down. We found that
:24:03. > :24:11.expansion was speeding up. We did not know what that was causing that
:24:11. > :24:18.and already we did not know what dark matter was, so we coined the
:24:18. > :24:21.expression dark energy. Can black holes hold the dark matter?
:24:21. > :24:26.There have been experiments to check for this with macro lenses.
:24:26. > :24:30.If the galaxy was full of little holes, we would be able to see that
:24:30. > :24:35.by staring at stars and seeing the twinkles. In a similar way to
:24:35. > :24:39.seeing what the planet hunters were doing. There would be a difference
:24:39. > :24:44.signal when you get a planet. They would twinkle because the black
:24:44. > :24:48.hole would pass in front of the star and Paul the light around it.
:24:48. > :24:53.That would actually make the star brighter for the moment. How are
:24:53. > :25:03.you doing, Jon? Dark matter and dark energy sound very sinister.
:25:03. > :25:06.is like a James Bond villain. Happy matter? Happy energy? As we saw,
:25:06. > :25:10.far from being dangerous, dark matter is probably the reason that
:25:10. > :25:15.we are here. Without the simulations that we have at the
:25:15. > :25:20.moment, there would not be any energy. Given that there are so
:25:20. > :25:26.many stars in the universe, is somebody watching, stargazing, and
:25:26. > :25:30.looking at us? If the universe is infinite, then yes. We can only see
:25:30. > :25:34.a little bit of the universe, which we call the observable universe. If
:25:34. > :25:37.you imagine as here, then there is a sphere around us from which
:25:38. > :25:41.lights have had time to reach us from the Big Bang. That is the edge
:25:41. > :25:46.of the observable universe. Beyond that we know there is more universe
:25:46. > :25:53.but we do not know if it goes on forever or not. If it did, there
:25:53. > :25:58.would be more Brian Coxs. There are already two and if they stand too
:25:58. > :26:03.close then they evaporate! We want you to go out and see what is in
:26:03. > :26:06.the sky above you and to help you, we have made this.
:26:06. > :26:12.Look South straight after the show tonight and hunt for the three
:26:13. > :26:16.stars in a row that make-up Orion's belt. A little closer to the
:26:16. > :26:21.horizon, you may be able to make out some brighter objects close
:26:21. > :26:25.together pointing down. These make- up Orion's sword. If the sky is
:26:25. > :26:30.dark and clear enough, in the middle of the sort you can see what
:26:30. > :26:36.looks like a fuzzy star. This is actually the Orion nebula, an area
:26:37. > :26:41.where new stars are forming. Still in the constellation of Orion, you
:26:41. > :26:48.can see a star at the other end of its life cycle. In the top left
:26:48. > :26:53.corner, the red super-giant. If you can get a good few of this star,
:26:53. > :26:59.you can see that it does look slightly red coloured. It is in the
:26:59. > :27:05.process of dying and one day it will explode and go supernova. If
:27:05. > :27:09.you look back up beyond Orion, there is more to find. At the very
:27:09. > :27:13.top of the constellation of Taurus, there is a tiny, closely packed
:27:13. > :27:19.group of stars. It is a star cluster of known as the seven
:27:19. > :27:23.sisters. The reason they are so close is that they all formed from
:27:23. > :27:29.the same gas cloud. On a much larger scale, looked to the West
:27:29. > :27:33.and you will be looking towards our nearest galaxy, Andromeda. It is
:27:33. > :27:40.above the tops dark in the Square of Pegasus. To the naked eye, it
:27:40. > :27:47.will look like a hazy smudge. It is actually bigger than our galaxy. If
:27:47. > :27:52.you are lucky enough to live in a very dark area, before the moon
:27:52. > :27:57.rises at 3am, try spotting our galaxy, the Milky Way. It is a
:27:57. > :28:07.dense fog of stars moving North West to South East, and passing
:28:07. > :28:10.
:28:10. > :28:14.through Casio and serious, the brightest star in this sky.
:28:14. > :28:18.Mark has also recorded audio guides which you can download from the
:28:18. > :28:22.website. There is so much information. How are we doing on
:28:22. > :28:27.the planet hunting? We have had half a million analyses done, which
:28:27. > :28:31.is unbelievable. We will keep doing it and I think we will find planets.
:28:31. > :28:36.Half-a-million? Let's make it 1 million by the end of the show.
:28:36. > :28:41.Have you enjoyed it? At salute you wonderful. Thank you to the
:28:41. > :28:51.Liverpool and Macclesfield astronomy club. -- absolutely
:28:51. > :28:52.