0:00:17 > 0:00:21This is Herstmonceux Castle, home of the Royal Greenwich Observatory
0:00:21 > 0:00:23and the headquarters of British astronomy.
0:00:23 > 0:00:26So this is a fitting place to begin our programme
0:00:26 > 0:00:31about the most momentous quarter-century in the whole history of astronomy.
0:00:31 > 0:00:35In 1957, when we began The Sky At Night programmes,
0:00:35 > 0:00:39the move from old Greenwich to Herstmonceux was barely completed.
0:00:39 > 0:00:44The great radio telescope at Jodrell Bank was only just coming into operation.
0:00:44 > 0:00:47But the most significant event of 1957
0:00:47 > 0:00:49was the opening of the space age,
0:00:49 > 0:00:55when Russia launched the first artificial satellite, Sputnik 1.
0:00:55 > 0:00:59The Russians had taken the lead but the Americans weren't far behind.
0:00:59 > 0:01:05Five, four, three, two, one, zero.
0:01:05 > 0:01:07All engines running. Lift-off!
0:01:07 > 0:01:11We have a lift-off! 32 minutes past the hour.
0:01:11 > 0:01:14Lift-off on Apollo 11.
0:01:14 > 0:01:22Apollo 11. And in July 1969, Neil Armstrong became the first man on the moon.
0:01:22 > 0:01:25OK, I'm going to step off the LEM now.
0:01:25 > 0:01:29He stepped out onto the bleak rocks of the sea of tranquillity.
0:01:29 > 0:01:34That's one small step for man...
0:01:34 > 0:01:38..one giant leap for mankind.
0:01:38 > 0:01:44By the time of Apollo 17, Commander Eugene Cernan was driving over the moon.
0:01:44 > 0:01:47His memory of that trip is as vivid as ever.
0:01:47 > 0:01:51For instance, what about navigation on the moon surface?
0:01:51 > 0:01:57We studied, due to a great deal of your work, of course, on the mapping of the moon,
0:01:57 > 0:02:02we studied the area we were going to land so well,
0:02:02 > 0:02:06that I really believe I knew it, at least from the air,
0:02:06 > 0:02:09from above, as well as I know my own backyard.
0:02:09 > 0:02:14However, when you do get down among the rocks and you do get down among the mountains,
0:02:14 > 0:02:17eh, you do have to re-familiarise yourself
0:02:17 > 0:02:19because things now start to look different.
0:02:19 > 0:02:22And navigation itself didn't bother us.
0:02:22 > 0:02:26But there's no trees, there's no roads, there's no houses,
0:02:26 > 0:02:28there's no telephone poles.
0:02:28 > 0:02:31So depth perception at distance is very difficult.
0:02:31 > 0:02:36You would look at something and instead of being a kilometre away,
0:02:36 > 0:02:40it might be ten kilometres away.
0:02:40 > 0:02:43You had no way to tell how far you were going or how far you had come.
0:02:43 > 0:02:46We knew the size of the Lunar Module.
0:02:46 > 0:02:50So we could always look back and see it and realise it was getting very small.
0:02:50 > 0:02:53But many times we went around the corner and over the mountain
0:02:53 > 0:02:56and then we were out of sight of the Lunar Module.
0:02:56 > 0:02:58So far, you're the last man on the moon.
0:02:58 > 0:03:02When do you think the next men will go there? Can you give any estimate?
0:03:02 > 0:03:04When there is a purpose, when there is reason,
0:03:04 > 0:03:07when there is motivation to go back to the moon,
0:03:07 > 0:03:11to use it as a base to further explore the Solar System
0:03:11 > 0:03:13or whatever, we will go back.
0:03:13 > 0:03:18Until that motivation comes from some source, it may be a long time.
0:03:18 > 0:03:22I believe we will go to Mars too. Again we'll need motivation.
0:03:22 > 0:03:25When the Viking spacecraft landed on Mars
0:03:25 > 0:03:28and the television camera scanned the surface,
0:03:28 > 0:03:32if there was a little green man with long ears looking back, that would have been motivation.
0:03:32 > 0:03:36We would have been on our way to Mars today
0:03:36 > 0:03:38if that kind of motivation occurred.
0:03:38 > 0:03:42It could be motivation from within or from without. Yeah.
0:03:42 > 0:03:46We'll go back to the moon. When, I just can't tell you.
0:03:46 > 0:03:50But there'll be someone who will follow our steps to the moon.
0:03:50 > 0:03:55Manned flight is only one facet of the space programme.
0:03:55 > 0:03:57Unmanned probes to the planets
0:03:57 > 0:04:01have produced some of the most unexpected results.
0:04:01 > 0:04:04The control centre is the Jet Propulsion Laboratory
0:04:04 > 0:04:08here at Pasadena in California.
0:04:08 > 0:04:12This is one of the most dramatic places in the world,
0:04:12 > 0:04:17even though it may not look it. It's the DSN or Deep Space Network.
0:04:17 > 0:04:20It's here that we receive information from probes so far away,
0:04:20 > 0:04:22that they make the moon look very parochial.
0:04:22 > 0:04:27And it's here that we receive those incredible pictures of the volcanoes of Io,
0:04:27 > 0:04:30the icy craters of Dione and the complicated rings of Saturn.
0:04:30 > 0:04:33Marvels that only the space probes can show us.
0:04:33 > 0:04:37The DSN is manned 24 hours per day and has been for a great many years.
0:04:37 > 0:04:41Remember, the first successful planetary probe, Mariner 2,
0:04:41 > 0:04:45by-passed Venus as long ago as 1962.
0:04:45 > 0:04:483571.
0:04:48 > 0:04:53Item one, NA, item two, command mode off. 0235.
0:04:53 > 0:04:58It was here that the most dramatic of all space pictures were received.
0:04:58 > 0:05:03The Voyager probes recorded the quick spin of the great red spot on Jupiter.
0:05:03 > 0:05:05now known to be a whirling storm.
0:05:13 > 0:05:15There were the satellites of Jupiter.
0:05:15 > 0:05:18Callisto, with its icy cratered surface,
0:05:18 > 0:05:22and Io, with its red surface, sulphur volcanoes and crusted lava lakes.
0:05:22 > 0:05:25There may be a sea of liquid sulphur underneath.
0:05:25 > 0:05:29Io, we discovered, is just about the most lethal world in the solar system,
0:05:29 > 0:05:33because it moves right inside Jupiter's deadly radiation zone.
0:05:33 > 0:05:37And beyond Jupiter, the Voyagers by-passed Saturn,
0:05:37 > 0:05:40showing the glorious rings which turned out to be grooved,
0:05:40 > 0:05:43for reasons still not properly understood.
0:05:43 > 0:05:46Then there is Titan, Saturn's largest satellite,
0:05:46 > 0:05:51with its thick nitrogen atmosphere, covering perhaps oceans of methane.
0:05:51 > 0:05:54And the icy satellites - look at Mimas, with one huge crater
0:05:54 > 0:05:59reminding one of the Death Star in the film Star Wars.
0:05:59 > 0:06:02We also send probes to study the inner solar system.
0:06:02 > 0:06:05Mariner 2 was the first probe to Venus.
0:06:05 > 0:06:08Then Mariner 10 went past Venus to Mercury.
0:06:08 > 0:06:11It recorded barren craters like those of the moon.
0:06:12 > 0:06:17But Venus, so like the Earth in size and mass, is a curious world.
0:06:17 > 0:06:20All we can see from above is the top of a cloud layer.
0:06:22 > 0:06:25The orbiting Pioneer probe maps Venus by radar,
0:06:25 > 0:06:27showing active volcanoes.
0:06:27 > 0:06:30The surface temperature is 900F.
0:06:30 > 0:06:34Venus may once have supported life but it certainly can't do so now.
0:06:36 > 0:06:41The Russian probes, Veneras 13 and 14, landed there in March 1982,
0:06:41 > 0:06:45sending back pictures of a very gloomy scene under an orange sky.
0:06:50 > 0:06:54On Mars, at least, there still seemed a chance of life.
0:06:55 > 0:07:00Unmanned probes such as Mariner 9 in 1971, showed craters,
0:07:00 > 0:07:02valleys and huge volcanoes.
0:07:04 > 0:07:09Mount Olympus rises for 15 miles, three times as high as Everest.
0:07:10 > 0:07:14Then came the two Vikings, which made controlled landings.
0:07:14 > 0:07:18They sent back pictures of a red rock-strewn landscape.
0:07:23 > 0:07:26Material was scooped up and analysed.
0:07:26 > 0:07:28But to the regret of most astronomers,
0:07:28 > 0:07:31the results showed no positive sign of life.
0:07:32 > 0:07:35The story of Mars is linked intimately
0:07:35 > 0:07:37with that of the Lowell Observatory.
0:07:37 > 0:07:40In fact, the road up to the observatory is called Mars Hill.
0:07:40 > 0:07:43The observatory was established in 1896
0:07:43 > 0:07:46by one of astronomy's great characters, Percival Lowell,
0:07:46 > 0:07:50because he thought, correctly, that seeing conditions here would be excellent.
0:07:50 > 0:07:53Um, despite the weather at the present moment.
0:07:55 > 0:07:59Lowell equipped his observatory with a 24-inch refracting telescope.
0:07:59 > 0:08:03It's an impressive instrument and still used for planetary research.
0:08:03 > 0:08:08One man who uses it regularly is Dr Charles Capen.
0:08:08 > 0:08:11It really is a superb instrument, and of very high quality, is it not?
0:08:11 > 0:08:14Eh, yes, it is. It's one of the finest
0:08:14 > 0:08:17optical instruments in use in America today.
0:08:17 > 0:08:20And of course, being a refractor,
0:08:20 > 0:08:22it's well designed for planetary research.
0:08:22 > 0:08:26It gets good high contrast and we can use very high powers
0:08:26 > 0:08:29with the telescope, which gives us large planetary images.
0:08:29 > 0:08:34And, of course, then you have to have quality optics when you have high power.
0:08:34 > 0:08:37I remember, it was Wednesday, February 24, 1980,
0:08:37 > 0:08:39when you and I were observing together with this telescope,
0:08:39 > 0:08:42- we discovered something rather interesting.- Oh, yes.
0:08:42 > 0:08:43That was a very exciting night.
0:08:43 > 0:08:47In fact, I think it was a couple of nights that we were out observing.
0:08:47 > 0:08:51We saw the north cap of Mars split in two.
0:08:51 > 0:08:57And this is something that doesn't occur very frequently on Mars.
0:08:57 > 0:09:02In fact, I have looked for nearly 20 years and never seen it there.
0:09:02 > 0:09:06Then all of a sudden, you and I were observing, there it appeared there one evening.
0:09:06 > 0:09:11- I remember that very well. We made drawings and compared them. They were pretty well identical.- Yes.
0:09:11 > 0:09:17The photographs I took that evening also showed this rift in the cap.
0:09:21 > 0:09:26The Lowell refractor is ideal for studying the planets which are nearby and bright.
0:09:26 > 0:09:32But for more distant objects, you need to collect as much light as possible.
0:09:32 > 0:09:36The Mount Wilson hundred inch reflector, completed in 1917,
0:09:36 > 0:09:40has about four times the diameter but collects 16 times as much light.
0:09:40 > 0:09:45And in the 1930s, a 200-inch mirror, with a far greater light grasp,
0:09:45 > 0:09:48was planned for nearby Palomar.
0:09:48 > 0:09:52The problems of handling glass for a 14.5 ton mirror were formidable.
0:09:52 > 0:09:55After a good many trials and tribulations,
0:09:55 > 0:09:58the mirror was eventually cast.
0:10:02 > 0:10:07It took months to cool, and many months more to grind the mirror to the correct curve.
0:10:11 > 0:10:15Inaugurated in 1948, the 200-inch at Palomar
0:10:15 > 0:10:19is still the biggest optical telescope successfully operating to this day.
0:10:19 > 0:10:22Admittedly, the Russians have built an even bigger one,
0:10:22 > 0:10:24but they haven't really solved all the problems
0:10:24 > 0:10:26about making a telescope as large as this.
0:10:26 > 0:10:29Further work is being done on it.
0:10:31 > 0:10:35Perhaps the way ahead lies with this, the multiple mirror telescope
0:10:35 > 0:10:39on Mount Hopkins in Arizona, built in 1979.
0:10:39 > 0:10:44It has not one but six primary mirrors, each 72 inches in diameter,
0:10:44 > 0:10:51working together, equal in light grasp to a 176-inch mirror.
0:10:51 > 0:10:55You may ask, "Why build a telescope as complicated as this?"
0:10:55 > 0:10:59Well, there are two main reasons. First, making six 72-inch mirrors
0:10:59 > 0:11:04is a great deal easier than making a single 176-inch mirror.
0:11:04 > 0:11:07And secondly, there's the question of cost.
0:11:07 > 0:11:10The MMT has cost only about one third the price
0:11:10 > 0:11:14of our equivalent telescope with comparable aperture.
0:11:14 > 0:11:17If you think that the MMT looks unlike a telescope,
0:11:17 > 0:11:21then what about this one? It's the solar telescope
0:11:21 > 0:11:23at Kit Peak, also in Arizona.
0:11:23 > 0:11:26The main body of the telescope doesn't have to move.
0:11:26 > 0:11:29The sun's light is reflected down the length of a tunnel
0:11:29 > 0:11:33and halfway back up again to produce an image in the laboratory.
0:11:33 > 0:11:36This is the tallest solar telescope in the world as well as the biggest.
0:11:36 > 0:11:41The heliostat, the top mirror, is 80 inches across - that's large by any standards.
0:11:41 > 0:11:44The function of the heliostat is to direct the sunlight down the tunnel.
0:11:44 > 0:11:47And it's a long, long way.
0:11:59 > 0:12:01Now I'm inside the main tunnel,
0:12:01 > 0:12:03travelling down in a kind of a cable car,
0:12:03 > 0:12:07which, believe me, is a lot easier than using the 100 or more steps.
0:12:07 > 0:12:10You may ask why this telescope has to be so large.
0:12:10 > 0:12:14The main reason is the observers want a really big solar image.
0:12:14 > 0:12:18And for this they want a large aperture and a long focal length.
0:12:18 > 0:12:22And of course, if they put the tunnel straight up into the air,
0:12:22 > 0:12:25it would be even higher than it is and more difficult to handle.
0:12:25 > 0:12:28So this is really the best design.
0:12:28 > 0:12:31This is halfway house. Remember what's happened.
0:12:31 > 0:12:34The sunlight has struck the big mirror at the top of the tunnel
0:12:34 > 0:12:37and is reflected onto the mirror at the bottom of the tunnel.
0:12:37 > 0:12:39It's then sent back up the tunnel, onto this mirror,
0:12:39 > 0:12:41which is absolutely flat.
0:12:41 > 0:12:45And that directs the sunlight down, again in a constant direction,
0:12:45 > 0:12:47through a hole in the floor, into the laboratory below
0:12:47 > 0:12:50where the main analysis is done.
0:12:51 > 0:12:54The sun is only 93 million miles away.
0:12:54 > 0:12:57And you might imagine that by now we had learned all about it.
0:12:57 > 0:13:01I can assure you, we haven't. We have found out a great deal.
0:13:01 > 0:13:03We know the sun produces its energy
0:13:03 > 0:13:05by what are known as nuclear reactions.
0:13:05 > 0:13:08Hydrogen is being converted into helium.
0:13:08 > 0:13:12The sun is radiating and losing mass at 400 million tonnes a second.
0:13:12 > 0:13:16The central temperature is of the order of 14 million degrees.
0:13:16 > 0:13:18Ever since the early 17th century,
0:13:18 > 0:13:21we've studied the dark patches, or sunspots.
0:13:21 > 0:13:24But recently, it's become clear that our knowledge of the sun
0:13:24 > 0:13:26is very far from complete.
0:13:26 > 0:13:31The latest discoveries have thrown new light on the nature of our nearest star.
0:13:31 > 0:13:34And to make these discoveries, solar astronomers now set up
0:13:34 > 0:13:37their experiments in the most unlikely places.
0:13:37 > 0:13:40This is the strangest of them all.
0:13:40 > 0:13:43Homestake Mine near Deadwood Gultch in South Dakota,
0:13:43 > 0:13:45land of the gunslingers of a century ago,
0:13:45 > 0:13:49Wild Bill Hickok, Calamity Jane, Dr Holliday and the rest.
0:13:49 > 0:13:53Gold has been mined here ever since 1877.
0:13:55 > 0:13:58But gold isn't what the astronomers are after.
0:13:58 > 0:14:02One mile underground, the mine provides a convenient hole
0:14:02 > 0:14:04for the astronomers to set up their observatory.
0:14:04 > 0:14:06But it's not the sun's light they're after,
0:14:06 > 0:14:08but some elusive solar particles.
0:14:08 > 0:14:11It seems a curious place to study the sun.
0:14:11 > 0:14:14Just why are you hiding so far underground?
0:14:14 > 0:14:16Well, we are trying to observe neutrinos.
0:14:16 > 0:14:19They produce a very small signal.
0:14:19 > 0:14:23And cosmic rays and many other nuclear particles
0:14:23 > 0:14:26produce the same signal we're looking for.
0:14:26 > 0:14:30So we have to come way underground and screen ourselves from cosmic rays.
0:14:30 > 0:14:32Do you get any cosmic rays down here?
0:14:32 > 0:14:36Yeah, there are a few. The number of cosmic rays
0:14:36 > 0:14:40passing through a square metre is kind of one every,
0:14:40 > 0:14:44every...oh, quarter of the day, something like that.
0:14:44 > 0:14:47Which is not very much. A neutrino, with no mass and no charge,
0:14:47 > 0:14:49is very difficult to detect. How do you trap it?
0:14:49 > 0:14:54Well, a neutrino is very penetrating and it goes right through the Earth.
0:14:54 > 0:14:57And we try to trap it in chlorine.
0:14:57 > 0:15:01It's captured by chlorine atom to produce radioactive argon atom.
0:15:01 > 0:15:06And we try to observe these few radioactive argon atoms produced.
0:15:06 > 0:15:09And you have your chlorine in a large tank of cleaning fluid?
0:15:09 > 0:15:14Yes. We have a very large tank. It holds 100,000 gallons
0:15:14 > 0:15:17of a chemical compound called perchlorethylene.
0:15:17 > 0:15:20It's a common dry-cleaning solvent.
0:15:20 > 0:15:22So we have 100,000 gallons of that as a detector.
0:15:22 > 0:15:24And what do the neutrinos do to it?
0:15:24 > 0:15:29Well, they convert a chlorine atom into a radioactive argon atom.
0:15:29 > 0:15:35So in that tank it produces one of these atoms every two days.
0:15:35 > 0:15:39And we have to remove that and observe its radioactivity.
0:15:39 > 0:15:42By noting the numbers of these particular atoms produced,
0:15:42 > 0:15:45- you know how many neutrinos have hit?- That's right, exactly.
0:15:45 > 0:15:47What are the results to date?
0:15:47 > 0:15:52The results to date are that we are observing too few neutrinos.
0:15:52 > 0:15:56Roughly a factor of four below theoretical expectation.
0:15:56 > 0:15:59- Why is that?- Well, we don't know.
0:15:59 > 0:16:02We've known for about 10 years that we're seeing a low signal
0:16:02 > 0:16:07and there have been many explanations suggested.
0:16:07 > 0:16:11Essentially, you can say that the central regions of the Sun
0:16:11 > 0:16:14are probably not as hot as we think they are.
0:16:14 > 0:16:17Ray, why is this experiment so important?
0:16:17 > 0:16:21Because the Sun is the closest star to us
0:16:21 > 0:16:23and we know a lot about the Sun.
0:16:23 > 0:16:29And to try to satisfactorily understand how the Sun operates,
0:16:29 > 0:16:31how it generates energy,
0:16:31 > 0:16:34that tells us about the life and death of all stars.
0:16:34 > 0:16:37Neutrinos may be difficult to catch but so, of course,
0:16:37 > 0:16:39is the light from the faintest
0:16:39 > 0:16:41and most distant stars and star systems.
0:16:41 > 0:16:45Astronomers need to make the most of what little light there is.
0:16:45 > 0:16:48An electronic device to help them do just that
0:16:48 > 0:16:51was developed by a team led by Professor Alec Boksenberg,
0:16:51 > 0:16:54now director of the Royal Greenwich Observatory
0:16:54 > 0:16:55at Herstmonceux in Sussex.
0:16:55 > 0:17:01Well, very basically, the idea is to look at single photons
0:17:01 > 0:17:05which are the particles of light, of which light is made up.
0:17:05 > 0:17:08One can't be more sensitive than that
0:17:08 > 0:17:10and the way it does it
0:17:10 > 0:17:13is first to intensify or amplify
0:17:13 > 0:17:17the very faint image that we get in astronomy
0:17:17 > 0:17:22by a very large factor - something like 10 or maybe 100 million.
0:17:22 > 0:17:26And when you do that, you find the single photons,
0:17:26 > 0:17:30which you normally can't appreciate when one looks at something by eye,
0:17:30 > 0:17:35but they show up as splashes of light, independent splashes of light.
0:17:35 > 0:17:39And the detector observes each splash of light
0:17:39 > 0:17:44with a television camera and then this is fed into a computer
0:17:44 > 0:17:48and gradually the very faint image builds up in the computer and
0:17:48 > 0:17:50we can see it on a television screen,
0:17:50 > 0:17:53just as if it were a photograph, in the end.
0:17:53 > 0:17:57Of course, it might take hours or even days to build this picture up.
0:17:58 > 0:18:00Even with the help of electronics,
0:18:00 > 0:18:02optical experiments need clear skies.
0:18:02 > 0:18:06La Palma in the Canary Islands is ideal and has been chosen by
0:18:06 > 0:18:09Britain and other European countries as a site for a new observatory.
0:18:09 > 0:18:12The INT, or Isaac Newton Telescope,
0:18:12 > 0:18:15has already been moved here from Herstmonceux.
0:18:15 > 0:18:17And here's the new dome with the INT,
0:18:17 > 0:18:21almost at the highest point of La Palma at over 7,000 feet,
0:18:21 > 0:18:23with most of the clouds below us.
0:18:23 > 0:18:25As an observing site, it's superb
0:18:25 > 0:18:28and incidentally, scenically magnificent.
0:18:28 > 0:18:30Inside the dome is the INT itself,
0:18:30 > 0:18:33expected to be fully operational by mid-1983.
0:18:35 > 0:18:38It won't be the only British telescope at La Palma.
0:18:38 > 0:18:41Work has already started on the site for a new one-metre telescope
0:18:41 > 0:18:44due for compilation late in 1983.
0:18:44 > 0:18:47And there are plans for another, twice the size of the INT.
0:18:49 > 0:18:52The 4.2 metre William Herschel Telescope will be one of the largest
0:18:52 > 0:18:55in the world and will provide British astronomers
0:18:55 > 0:18:57with great opportunities.
0:18:57 > 0:19:00The project scientist at La Palma is Dr Paul Murdin.
0:19:01 > 0:19:05The main research is going to be research which exploits
0:19:05 > 0:19:08the fantastic site that we're standing at.
0:19:08 > 0:19:12This site is very dark, very clear, it has very good seeing
0:19:12 > 0:19:15and it will see very, very faint things very far away.
0:19:15 > 0:19:17I think the main thrust of the work
0:19:17 > 0:19:21which will be done by British astronomers at the site -
0:19:21 > 0:19:25particularly with the 4.2 metre telescope - will be cosmological.
0:19:25 > 0:19:29We will penetrate further and further in look-back
0:19:29 > 0:19:34to the start of the universe and penetrate cosmological problems.
0:19:34 > 0:19:38Well, with a very large telescope here under pretty ideal conditions,
0:19:38 > 0:19:41I think we may expect some fairly spectacular advances.
0:19:41 > 0:19:43I'm sure that's true.
0:19:43 > 0:19:45You can't possibly be an astronomer now with a telescope
0:19:45 > 0:19:50like this at a site like this and not make fantastic discoveries.
0:19:50 > 0:19:52Splendid though La Palma is,
0:19:52 > 0:19:54it can hardly rival the magnificence of Hawaii.
0:19:54 > 0:19:58Here, we have the extinct volcano of Mauna Kea
0:19:58 > 0:20:01rising to nearly 14,000 feet above sea level.
0:20:01 > 0:20:03The air is thin and you have to be very careful
0:20:03 > 0:20:05not to move around too quickly.
0:20:05 > 0:20:08But here, above 40% of the Earth's atmosphere,
0:20:08 > 0:20:10seeing conditions are superb
0:20:10 > 0:20:13and four major telescopes have been set up.
0:20:13 > 0:20:19There's the 150-inch UKIRT, United Kingdom Infrared Telescope.
0:20:19 > 0:20:21Then there's the 88-inch reflector
0:20:21 > 0:20:24operated by the University of Hawaii.
0:20:24 > 0:20:28Then the giant 144 inch Canada France Hawaii,
0:20:28 > 0:20:29or CFH Telescope.
0:20:29 > 0:20:33And there's also a 120 inch infrared telescope operated by NASA.
0:20:33 > 0:20:35It's an impressive array
0:20:35 > 0:20:39and yet one can hardly say that the site is accessible.
0:20:39 > 0:20:42For one thing, it's a long, rough ride from Hilo,
0:20:42 > 0:20:46the largest town on the island and also it's very, very high.
0:20:46 > 0:20:50You have to stop for a while to acclimatise at the halfway house,
0:20:50 > 0:20:54Hale Pohaku, before starting the final half-hour drive
0:20:54 > 0:20:57up the very steep, rough track to the summit.
0:21:01 > 0:21:04Astronomers come here from all over the world and every time
0:21:04 > 0:21:07they use the telescope they have to make this trek as it's considered
0:21:07 > 0:21:11dangerous to sleep at 14,000 feet where the air is so thin.
0:21:12 > 0:21:15But this makes the site ideal for infrared studies
0:21:15 > 0:21:18and much of the research here is devoted to it.
0:21:18 > 0:21:20TRUNDLING
0:21:23 > 0:21:25Dr Dale Cruickshank has been using the 88 inch
0:21:25 > 0:21:27University of Hawaii Telescope
0:21:27 > 0:21:31for his own infrared studies of the solar system.
0:21:31 > 0:21:32That's right.
0:21:32 > 0:21:35My colleagues and I have been using this telescope from its vantage point
0:21:35 > 0:21:38high in the sky to explore the solar system
0:21:38 > 0:21:41both outward from the Sun and in toward the Sun.
0:21:41 > 0:21:43What are the main results so far?
0:21:43 > 0:21:47We've found exciting things about volcanoes on Io,
0:21:47 > 0:21:49the most interesting satellite of Jupiter.
0:21:49 > 0:21:53We've found that asteroids are an enormous range of objects
0:21:53 > 0:21:56in terms of their surface compositions and a wide variety
0:21:56 > 0:22:00of other things about the small and large objects in our neighbourhood.
0:22:00 > 0:22:03Dale, what do you see as the future of infrared astronomy
0:22:03 > 0:22:04in the solar system?
0:22:04 > 0:22:08From vantage points such as this there's a tremendous amount
0:22:08 > 0:22:10we can do over the next decades.
0:22:10 > 0:22:13Using the preliminary results given to us by spacecraft,
0:22:13 > 0:22:17we now can explore what's going on in the solar system in great detail
0:22:17 > 0:22:20and we look forward to an enormous range of exciting topics
0:22:20 > 0:22:23and discoveries over the next many years to come.
0:22:23 > 0:22:25Lastly, you've been using the 88 inch,
0:22:25 > 0:22:27are you going to use the UKIRT for this kind of research?
0:22:27 > 0:22:30Oh, yes. The UKIRT Telescope is a superb instrument for work
0:22:30 > 0:22:33in the kind of area that I study and I'm confident that it will
0:22:33 > 0:22:36continue to give me exciting results.
0:22:36 > 0:22:38What's so special about the UKIRT?
0:22:38 > 0:22:40It's turned out to be just as good as an ordinary telescope
0:22:40 > 0:22:42but because it was built for work in the infrared,
0:22:42 > 0:22:44the mirror didn't have to be so rigid
0:22:44 > 0:22:48and the optical design was less critical. Alan Pickup explains.
0:22:48 > 0:22:50Well, the principal difference is that the mirror is
0:22:50 > 0:22:51a lightweight mirror.
0:22:51 > 0:22:53A telescope of this aperture - 3.8 metres -
0:22:53 > 0:22:57would normally have a mirror of about 15 tonnes weight.
0:22:57 > 0:22:58UKIRT's mirror is only 6.5 tonnes
0:22:58 > 0:23:02and this makes the whole structure of the telescope much lighter and cheaper to build.
0:23:02 > 0:23:06There's a wonderful system known as chopping, can you tell us a bit about that?
0:23:06 > 0:23:08Yes, we like to separate out the infrared signal
0:23:08 > 0:23:10from the star from the infrared signal of the sky.
0:23:10 > 0:23:13Of course the sky is giving out infrared waves
0:23:13 > 0:23:16as well as a star or galaxy, whatever we're looking at.
0:23:16 > 0:23:19So we do this by looking at two small adjacent small areas of sky.
0:23:19 > 0:23:21In one of these areas of sky we place the star
0:23:21 > 0:23:24and the nearby area of sky, we just have the sky.
0:23:24 > 0:23:28By subtracting the two signals we receive from each of these areas,
0:23:28 > 0:23:30we can examine just the signal from the star
0:23:30 > 0:23:33and we do this by tilting the small secondary mirror
0:23:33 > 0:23:34of the telescope at the top.
0:23:34 > 0:23:38By tilting this we can effectively alter the pointing direction
0:23:38 > 0:23:40of the main telescope about 10 times every second.
0:23:40 > 0:23:42And this enables us to do this chopping
0:23:42 > 0:23:44between one position and another.
0:23:46 > 0:23:49But Hawaii is still north of the equator.
0:23:49 > 0:23:52We need major observatories in the southern hemisphere as well.
0:23:55 > 0:23:58This is a peaceful place in the Warrumbungle Mountains
0:23:58 > 0:24:00in the heart of New South Wales.
0:24:00 > 0:24:04It's a timeless place where kangaroos and koalas roam at night
0:24:04 > 0:24:08and it seems hardly to have altered since these volcanoes
0:24:08 > 0:24:11were finally quietened 13 million years ago.
0:24:11 > 0:24:13But this is Siding Spring Mountain,
0:24:13 > 0:24:16the home of one of the most sophisticated pieces
0:24:16 > 0:24:18of modern engineering.
0:24:18 > 0:24:21This is the dome of the Anglo-Australian Telescope, or AAT.
0:24:21 > 0:24:23It dominates the scene.
0:24:23 > 0:24:28It's 150 feet high, and it and the telescope weigh over 7,000 tonnes.
0:24:28 > 0:24:31Fortunately, it's built on firm foundations.
0:24:31 > 0:24:34These ancient volcanoes are very solid indeed.
0:24:34 > 0:24:36One is used to thinking of observatories
0:24:36 > 0:24:38perched on the tops of mountains.
0:24:38 > 0:24:40Well, there are no really high mountains in Australia
0:24:40 > 0:24:44but Siding Spring at well over 4,000 feet is quite lofty
0:24:44 > 0:24:46and conditions here are good.
0:24:46 > 0:24:49The decision to site a major telescope here was made in the
0:24:49 > 0:24:551960s but it wasn't until 1975 that the AAT came into full operation.
0:24:55 > 0:24:59The mirror is 153 inches across and is generally regarded
0:24:59 > 0:25:01as the finest ever made.
0:25:01 > 0:25:04The telescope itself is fairly conventional
0:25:04 > 0:25:07but it has one of the most sophisticated control rooms.
0:25:08 > 0:25:09Very nice.
0:25:11 > 0:25:13Using the most up-to-date techniques,
0:25:13 > 0:25:16the telescope can be guided from here.
0:25:18 > 0:25:22The observer seldom needs to go near the actual telescope at all.
0:25:24 > 0:25:26Most observations are made electronically
0:25:26 > 0:25:29and the results displayed and analysed in complete comfort.
0:25:31 > 0:25:33It's true that during the last ten years,
0:25:33 > 0:25:36astronomy has gone through an electronic revolution.
0:25:36 > 0:25:40Just as, long ago, the photographic plates replaced the human eye
0:25:40 > 0:25:43for most branches of research, so the plate is itself being
0:25:43 > 0:25:47superseded by electronic detectors for most purposes -
0:25:47 > 0:25:48but not all.
0:25:48 > 0:25:51There are some branches of research in which photography
0:25:51 > 0:25:54still reigns supreme and probably always will.
0:25:54 > 0:25:57And for photographic work, the AAT is ideal.
0:25:57 > 0:26:00One man who's taken full advantage of this, and has developed new
0:26:00 > 0:26:03techniques which are proving to be of immense value,
0:26:03 > 0:26:04is David Malin.
0:26:10 > 0:26:13David, how does photographing with the AAT
0:26:13 > 0:26:15differ from photographing with an ordinary telescope?
0:26:15 > 0:26:17Oh, in several ways.
0:26:17 > 0:26:19I think the best thing I can do is to demonstrate first of all
0:26:19 > 0:26:22the size of the photographic plate we have to use.
0:26:22 > 0:26:25This is a typical plate used on the AAT, 10 inches square,
0:26:25 > 0:26:28much larger than any other normal format.
0:26:28 > 0:26:32The second major difference is the fact that our exposure times
0:26:32 > 0:26:36are extremely long - typically 60 minutes, sometimes longer.
0:26:36 > 0:26:37Can astronomical photography
0:26:37 > 0:26:40still produce really valuable scientific results?
0:26:40 > 0:26:42Oh, yes. It's still very important.
0:26:42 > 0:26:45You've mentioned previously the electronic revolution which
0:26:45 > 0:26:48has come to pass in astronomy in the last 10 years but photography
0:26:48 > 0:26:53is still absolutely vital for many branches of astronomy.
0:26:53 > 0:26:59Mainly because we get an enormous area of information in one exposure.
0:26:59 > 0:27:03- What about colour photography? - Well, colour photography can be done.
0:27:03 > 0:27:06Colour film used to be used some years ago
0:27:06 > 0:27:09but now we've found that taking three black-and-white plates
0:27:09 > 0:27:11through colour separation filters is the way ahead
0:27:11 > 0:27:13and we're able to make colour pictures
0:27:13 > 0:27:15of extremely faint objects that way.
0:27:15 > 0:27:17David, these are magnificent colour pictures.
0:27:17 > 0:27:19Let's begin with the Orion Nebula.
0:27:19 > 0:27:23Yes, it forms the very famous shape of the horsehead
0:27:23 > 0:27:26which is a dark cloud of gas...dust, rather,
0:27:26 > 0:27:30spreading into the bright nebulosity of the horsehead itself.
0:27:30 > 0:27:34These colours are really striking. Are they genuine colours?
0:27:34 > 0:27:36They are representative colours,
0:27:36 > 0:27:39I think, is the best way to describe them.
0:27:39 > 0:27:42We've taken considerable pains to balance the three colours -
0:27:42 > 0:27:45the red, green and blue - in the photographs
0:27:45 > 0:27:48but these objects are emission line objects, they're not
0:27:48 > 0:27:53like objects that you normally photograph with your everyday camera.
0:27:53 > 0:27:55They are composed of discrete lines of emission
0:27:55 > 0:27:58and to balance photographs with line of emission is very difficult
0:27:58 > 0:28:00but we think we're well on the way towards doing that.
0:28:00 > 0:28:04I ask as so many people think, having seen these pictures, you can look through the telescope
0:28:04 > 0:28:06and see the colours but of course you can't.
0:28:06 > 0:28:08Unfortunately that's not true.
0:28:08 > 0:28:10Even with a large telescope, the light levels are so low that the
0:28:10 > 0:28:14eye is working in its mode where it doesn't record any colour at all.
0:28:14 > 0:28:18And here we have a very delicate one, the Filamentary Nebula
0:28:18 > 0:28:20- which contains the Vela pulsar, a supernova remnant.- Yes.
0:28:20 > 0:28:23This is an extremely low surface-brightness, very faint object,
0:28:23 > 0:28:26never been recorded in colour before and it's the remnant
0:28:26 > 0:28:30of the Vela supernova which exploded...well, some 10,000 years ago.
0:28:32 > 0:28:34And now going out beyond our own Milky Way, we come to
0:28:34 > 0:28:37the spiral galaxies and that is a magnificent picture
0:28:37 > 0:28:38of a spiral galaxy.
0:28:38 > 0:28:41If we could get outside our own galaxy and look back into it,
0:28:41 > 0:28:45that's pretty much what you might expect to see.
0:28:45 > 0:28:48An object with old, mature yellow stars in the middle,
0:28:48 > 0:28:51bluish spiral arms and along the spiral arms
0:28:51 > 0:28:52dotted are the red H2 regions,
0:28:52 > 0:28:55like Orion, that you can see along the spiral arms here.
0:28:56 > 0:28:59And now we come to this very interesting point,
0:28:59 > 0:29:04of rings round elliptical galaxies and I gather these have been
0:29:04 > 0:29:07discovered by you using your new techniques?
0:29:07 > 0:29:11Yes, this picture was taken with the UK Schmidt
0:29:11 > 0:29:15but the plates were massaged by techniques I've developed here
0:29:15 > 0:29:18and in doing so you are able to see some very faint shells.
0:29:18 > 0:29:23Here is one such. We call them shells because of their luminosity profile.
0:29:23 > 0:29:26Shells around these apparently quite normal galaxies
0:29:26 > 0:29:28and the existence of these is rather puzzling
0:29:28 > 0:29:31but we're working on it to find out exactly what they are
0:29:31 > 0:29:33and to come up with some kind of model
0:29:33 > 0:29:35which would explain their existence.
0:29:35 > 0:29:39That, I think, gives one very striking demonstration,
0:29:39 > 0:29:42that photography - and I mean photography, not electronics -
0:29:42 > 0:29:44is still very much a major force in modern astronomy.
0:29:44 > 0:29:46It's still very important.
0:29:46 > 0:29:48We've heard previously that electronics
0:29:48 > 0:29:50is taking over from photography
0:29:50 > 0:29:53but in fact the two techniques are complimentary.
0:29:53 > 0:29:56Photography is still capable of making significant new discoveries
0:29:56 > 0:29:58and it does so regularly, especially with the fine plates
0:29:58 > 0:30:01taken on this telescope and on the UK Schmidt.
0:30:01 > 0:30:04I don't think anyone will doubt that these photographs are the best
0:30:04 > 0:30:07deep-sky pictures ever obtained but today photography
0:30:07 > 0:30:10and electronics are complementary.
0:30:10 > 0:30:13Dr David Allen has been at Siding Spring for seven years
0:30:13 > 0:30:15and he knows every aspect of the AAT.
0:30:15 > 0:30:19- Of course, with this telescope, you did identify the Vela pulsar.- Mm.
0:30:19 > 0:30:21Which I believe is the faintest single object ever recorded,
0:30:21 > 0:30:24- am I right? - It's the faintest star ever studied.
0:30:24 > 0:30:27This is one of the things that the radio astronomers find,
0:30:27 > 0:30:30going "bleep-bleep-bleep" every 11 times a second, I think.
0:30:30 > 0:30:33And previously, only the Crab Nebula,
0:30:33 > 0:30:37the pulsar inside the Crab Nebula was known to flash in the visible
0:30:37 > 0:30:39whereas there are hundreds of these things
0:30:39 > 0:30:40flashing around in the radio sky.
0:30:40 > 0:30:43People thought they ought to have a look for more optical ones
0:30:43 > 0:30:45and it was apparent that they needed to be young.
0:30:45 > 0:30:46So the youngest was the Vela
0:30:46 > 0:30:49which is only accessible in the southern hemisphere.
0:30:49 > 0:30:51It's a few years now since the measurement was made
0:30:51 > 0:30:53but we managed to detect it. We saw the thing flashing on and off.
0:30:53 > 0:30:56In fact, it flashes slightly differently in the optical
0:30:56 > 0:30:57than it does in the radio.
0:30:57 > 0:31:00It's telling us something about how pulsars work.
0:31:00 > 0:31:03It seems to say that as they get older,
0:31:03 > 0:31:06the light they put out is falling very fast.
0:31:06 > 0:31:08In fact, so fast that I suspect if we'd been a century or two
0:31:08 > 0:31:12later in looking for this thing, we wouldn't have seen it. It would've faded out completely.
0:31:12 > 0:31:15Optical astronomy has developed in a way that was quite
0:31:15 > 0:31:18unforeseen 25 years ago when The Sky At Night started.
0:31:19 > 0:31:22Another branch of astronomy in its infancy then
0:31:22 > 0:31:26needs a very different kind of telescope - radio astronomy.
0:31:26 > 0:31:30And this is the world's most famous radio telescope,
0:31:30 > 0:31:33the 250 foot dish at Jodrell Bank in Cheshire.
0:31:33 > 0:31:36It's a colossal structure,
0:31:36 > 0:31:39capable of picking up radio waves from objects so remote
0:31:39 > 0:31:43that their signals take thousands of millions of years to reach us.
0:31:43 > 0:31:45And it's not only the world's most famous radio telescope,
0:31:45 > 0:31:49it was also the first really large instrument of its kind.
0:31:49 > 0:31:51It was set up because of the skill
0:31:51 > 0:31:55and persistence of one man, Professor Sir Bernard Lovell.
0:31:55 > 0:31:57There were plenty of problems to the overcome,
0:31:57 > 0:31:59not all of them scientific.
0:31:59 > 0:32:01But we still had to find the money.
0:32:01 > 0:32:05I mean, by that time the bill for the telescope, for which
0:32:05 > 0:32:09I had only got a third of a million, had gone up to £680,000.
0:32:09 > 0:32:14We collected £100,000 fairly quickly
0:32:14 > 0:32:21and then we were stuck for the remaining 50 or 60 thousand pounds.
0:32:21 > 0:32:23By this time, it was 1960
0:32:23 > 0:32:30and we were part of the ground network of the American space effort.
0:32:30 > 0:32:34We had come to this arrangement with great secrecy
0:32:34 > 0:32:38with what was then the United States Air Force.
0:32:38 > 0:32:41And Pioneer 5, the first series of Pioneer 5s,
0:32:41 > 0:32:45we had the job of actually, not tracking it,
0:32:45 > 0:32:48but actually commanding it from this telescope.
0:32:48 > 0:32:51We sent out transmitted signals which,
0:32:51 > 0:32:55about 20 minutes after it was launched from Cape Kennedy,
0:32:55 > 0:32:59we released the space probe from its carrier rocket.
0:32:59 > 0:33:04And of course this was all over the newspapers, front-page news.
0:33:05 > 0:33:12The next day, the telephone rang and at the other end, a man said,
0:33:12 > 0:33:14"Is that Lovell?" "Yes."
0:33:14 > 0:33:19"My name is Kingerlee. I'm Lord Nuffield's secretary.
0:33:19 > 0:33:22"His Lordship wishes to speak to you."
0:33:22 > 0:33:24So Lord Nuffield came on the phone.
0:33:24 > 0:33:26"Is that Lovell?" "Yes, my Lord."
0:33:26 > 0:33:29How much money for that telescope of yours?"
0:33:29 > 0:33:31I said, "About 50,000."
0:33:31 > 0:33:34"Is that all? I'll send you a cheque."
0:33:34 > 0:33:36So that was a relief.
0:33:36 > 0:33:39After the strange and incredibly powerful quasars,
0:33:39 > 0:33:42or QSOs were identified in 1963,
0:33:42 > 0:33:45they were intensively studied from Jodrell Bank.
0:33:45 > 0:33:49Sir Bernard retired as director at the end of October 1981 -
0:33:49 > 0:33:50the end of an era.
0:33:50 > 0:33:53But he's been succeeded by another great radio astronomer -
0:33:53 > 0:33:56Prof. Graham Smith.
0:33:56 > 0:34:00Graham, what about the Quasars? What are the latest developments?
0:34:00 > 0:34:03I think that's the main bulk of work here.
0:34:03 > 0:34:08You know that the telescope's used in collaboration with others
0:34:08 > 0:34:09to produce maps of quasars.
0:34:09 > 0:34:11This is the most exciting thing
0:34:11 > 0:34:14because we can produce very accurate maps.
0:34:14 > 0:34:17We find that quasars have got a very complicated structure.
0:34:17 > 0:34:21There are some very strange physical things going on there.
0:34:21 > 0:34:23They are storehouses of energy
0:34:23 > 0:34:26and they are producing radiation at a fantastic rate
0:34:26 > 0:34:30in little hotspots at the centres and far out from the centre.
0:34:30 > 0:34:32What do you think a quasar is?
0:34:32 > 0:34:37It's got a certain powerhouse in the centre which we don't understand.
0:34:37 > 0:34:40Probably a black hole but everybody says probably a black hole
0:34:40 > 0:34:43because they don't know where the energy's coming from.
0:34:43 > 0:34:47It could be a rotating black hole. That's the most likely theory.
0:34:47 > 0:34:50Quasars weren't actually discovered here.
0:34:50 > 0:34:53In fact, the first positive quasar identification
0:34:53 > 0:34:58came from the Parkes Radio Astronomy Observatory in New South Wales.
0:34:58 > 0:35:02It was an object which was known to be a radio source -
0:35:02 > 0:35:05that is a source of radio radiation -
0:35:05 > 0:35:07to be an extremely small source.
0:35:07 > 0:35:14It had very little size and the identification was made by using the moon.
0:35:14 > 0:35:17As the moon slowly passed across the source, the radiation was cut off
0:35:17 > 0:35:20and, by knowing the precise time at which the moon
0:35:20 > 0:35:24cut across the object, we were able to get an accurate position.
0:35:24 > 0:35:28This led, on a comparison with an optical plate,
0:35:28 > 0:35:33to a identification with this object - 3C273 - the first quasar.
0:35:33 > 0:35:37When 3C273 was examined optically, I think it was in Panama,
0:35:37 > 0:35:39astronomers there had a considerable shock.
0:35:39 > 0:35:41Oh, a very considerable shock.
0:35:41 > 0:35:45The spectrum was unlike that of any known star and, at that time,
0:35:45 > 0:35:48it was thought that the objects were stars.
0:35:48 > 0:35:49In fact, they were called radio stars.
0:35:49 > 0:35:52We now know that they were like no known stars.
0:35:52 > 0:35:54They were objects way across the universe.
0:35:54 > 0:35:57In fact, near the distant edges of the universe.
0:35:57 > 0:36:00We're used to talking about redshifts in optical terms
0:36:00 > 0:36:02but you can so the same thing with a radio telescope.
0:36:02 > 0:36:06Are we certain that these redshifts really do indicate these
0:36:06 > 0:36:12- immense consistencies?- 90% of people think so.- What do you think?- No.
0:36:12 > 0:36:14I think... Let me put it this way.
0:36:14 > 0:36:16On Monday, Tuesday and Wednesday,
0:36:16 > 0:36:18I think they are indicative of distance,
0:36:18 > 0:36:21but perhaps on Thursday and Friday, they're not.
0:36:21 > 0:36:25There is, I think, a growing body of evidence that favours
0:36:25 > 0:36:30the fact that the redshifts are not cosmological.
0:36:30 > 0:36:34That is that they indicate enormous distances for the QSOs.
0:36:34 > 0:36:37A particularly exciting bit of work done in the States
0:36:37 > 0:36:42was on the object I referred to at the beginning - 3C273.
0:36:42 > 0:36:47When it was shown that two radio sources in 3C273
0:36:47 > 0:36:50are moving apart at a very high speed.
0:36:50 > 0:36:55In fact, if 3C273 is at the distance we really thing it's at,
0:36:55 > 0:36:57as determined by the redshift,
0:36:57 > 0:37:01then these objects are moving apart at ten times the speed of light.
0:37:01 > 0:37:06- That's surely impossible.- That is impossible on conventional physics.
0:37:06 > 0:37:10And if 3C273 is at its correct distance and if there's nothing
0:37:10 > 0:37:14wrong with the radio observations, one of those three things is wrong.
0:37:14 > 0:37:16I would very much like to know which it is.
0:37:16 > 0:37:19Prof Sir Fred Hoyle has no doubts at all.
0:37:19 > 0:37:23I don't belief that the redshifts are indicative of their distance.
0:37:23 > 0:37:24I think that's nonsense.
0:37:24 > 0:37:27There's overwhelming evidence to show that it's nonsense.
0:37:27 > 0:37:34- What evidence is there?- There's far too many quasars found in clusters.
0:37:34 > 0:37:41There are also cases known of triplets of quasars
0:37:41 > 0:37:44which are in line with each other - the three of a triplet -
0:37:44 > 0:37:50to within the accuracy that one can determine by measurements
0:37:50 > 0:37:55on the base telescopes, which is well within a second of arc
0:37:55 > 0:37:59and such geometrical arrangements, they're not entirely impossible
0:37:59 > 0:38:02but they're exceedingly unlikely.
0:38:02 > 0:38:06I think this notion that quasar redshifts
0:38:06 > 0:38:10are indicative of cosmological distances is just wrong.
0:38:10 > 0:38:12It's obviously wrong.
0:38:12 > 0:38:15In your view, how far away are the quasars?
0:38:15 > 0:38:18I don't know how far away they are.
0:38:18 > 0:38:20I think they're comparatively close
0:38:20 > 0:38:23and I think they are huge aggregations of mass.
0:38:23 > 0:38:26- In our galaxy or beyond? - Oh, beyond. Beyond.
0:38:26 > 0:38:31Maybe 100 million light years. That sort of distance.
0:38:31 > 0:38:36- How does Prof Graham Smith view this argument?- That's dying down.
0:38:36 > 0:38:40That's come and gone in this 25 years.
0:38:40 > 0:38:43I don't think there's much fight left in it.
0:38:43 > 0:38:45They are indeed distant objects.
0:38:45 > 0:38:48They are objects which are giving us
0:38:48 > 0:38:51information about the history of the universe as well as about themselves.
0:38:51 > 0:38:53When you say distant objects,
0:38:53 > 0:38:56- do you mean thousands of millions of light years?- Oh, yes.
0:38:56 > 0:39:01The most distant objects available in the universe are these quasars
0:39:01 > 0:39:03and the radio galaxies.
0:39:03 > 0:39:06So we have two completely opposite theories,
0:39:06 > 0:39:08each supported by eminent astronomers.
0:39:08 > 0:39:10Quasars have certainly caused arguments.
0:39:10 > 0:39:13But during a quasar research programme at Cambridge,
0:39:13 > 0:39:17using a peculiar-lookig aerial array covering over four acres,
0:39:17 > 0:39:21a team, led by Prof Antony Hewish, made an unexpected discovery,
0:39:21 > 0:39:23more or less by accident.
0:39:23 > 0:39:27We were making observations of quasars and watching them
0:39:27 > 0:39:31as clouds of gas blew from the sun across the quasar.
0:39:31 > 0:39:33This gives you a flickering signal
0:39:33 > 0:39:35we can use to measure
0:39:35 > 0:39:38the sizes of these objects and that's an important measurement.
0:39:38 > 0:39:41The telescope was designed to see this effect -
0:39:41 > 0:39:44plasma clouds passing quasar sources.
0:39:44 > 0:39:47When the pulsar came,
0:39:47 > 0:39:51we obtained the flickering signal which looked like this effect.
0:39:51 > 0:39:55Normally one only sees this during the hours of daylight
0:39:55 > 0:39:58because the line of sight is reasonably close to the sun.
0:39:58 > 0:40:00We were making a routine survey
0:40:00 > 0:40:04and the records were being analysed by Jocelyn Bell
0:40:04 > 0:40:08and she saw a signal which we first thought was the fluctuation
0:40:08 > 0:40:11we were looking for but it happened at the wrong time of day.
0:40:11 > 0:40:13We looked at every inch of the record and she found this thing
0:40:13 > 0:40:16in the middle of the night instead of the middle of the day
0:40:16 > 0:40:18and she pointed my attention to it and we decided that,
0:40:18 > 0:40:21since we were doing repeated measurements, it would come up again
0:40:21 > 0:40:25if it was a genuine signal and that's how we got onto it.
0:40:25 > 0:40:29It came up once in while and so we made a detailed investigation
0:40:29 > 0:40:32and found these regular pulses, much to everyone's astonishment.
0:40:32 > 0:40:33What did you think it was?
0:40:33 > 0:40:36I thought to begin with it was probably radio interference.
0:40:36 > 0:40:37It looked so totally artificial
0:40:37 > 0:40:41but the detailed follow-up work showed that it couldn't be that.
0:40:41 > 0:40:44It was coming from a particular point in the sky that
0:40:44 > 0:40:46maintained its position quite accurately.
0:40:46 > 0:40:49That pointed us to a celestial source,
0:40:49 > 0:40:50a genuine astronomical phenomenon.
0:40:50 > 0:40:54- This was the first pulsar, in fact. - The very first pulsar.
0:40:54 > 0:40:57A very recent discovery has been the first pulsar
0:40:57 > 0:40:59beyond our galaxy in the Large Magellanic Cloud
0:40:59 > 0:41:03more than 150,000 light years away.
0:41:03 > 0:41:05That discovery couldn't be made from Cambridge
0:41:05 > 0:41:07because the cloud is too far south in the sky.
0:41:07 > 0:41:10It was made from Parkes by Dr Jon Ables.
0:41:11 > 0:41:15You understand that pulsars are galactic objects.
0:41:15 > 0:41:19They are the result of the death of certain kinds of stars.
0:41:19 > 0:41:22The big ones, the ones that live fast, die young
0:41:22 > 0:41:24and leave fascinating corpses.
0:41:25 > 0:41:30This is the first time we've found a pulsar outside our own galaxy
0:41:30 > 0:41:32and it's been done with this telescope
0:41:32 > 0:41:35and my colleagues from the university in Tasmania.
0:41:35 > 0:41:38How did you locate this pulsar?
0:41:38 > 0:41:41Actually, we've been looking for years.
0:41:41 > 0:41:43We're not alone.
0:41:43 > 0:41:46Each time we looked, we used better methods, better receiving equipment,
0:41:46 > 0:41:48better techniques.
0:41:48 > 0:41:52Slowly, perhaps, too slowly, it dawned on us that we had really
0:41:52 > 0:41:56to go all out, use every trick we knew and that's what we did.
0:41:58 > 0:42:01We used the very best equipment we could build or lay our hands on.
0:42:01 > 0:42:05We used that - one of the best radio telescopes in the world.
0:42:05 > 0:42:10We used the best computing techniques that we could invent or steal.
0:42:10 > 0:42:13And we finally got one.
0:42:13 > 0:42:17Increasingly, scientists in all branches of astronomy
0:42:17 > 0:42:20are pushing their equipment and techniques to the very limits,
0:42:20 > 0:42:22to make more and more exciting discoveries
0:42:22 > 0:42:24about our unfolding universe.
0:42:24 > 0:42:26For radio-astronomers,
0:42:26 > 0:42:29the way ahead seems to lie in the linking of telescopes
0:42:29 > 0:42:32as far apart as Parkes in Australia and Jodrell Bank in England,
0:42:32 > 0:42:35to increase the accuracy of the observations.
0:42:35 > 0:42:37But for optical astronomers,
0:42:37 > 0:42:40the Earth's atmosphere is the limiting factor.
0:42:40 > 0:42:42And there's even an answer to that.
0:42:42 > 0:42:46Eight, seven, six, five, four...
0:42:46 > 0:42:49We've gone for main engine start. We have main engine start.
0:42:55 > 0:42:57..America's first space shuttle.
0:42:57 > 0:43:00And the shuttle has cleared the tower.
0:43:04 > 0:43:08The plan is to use the shuttle to launch a space telescope -
0:43:08 > 0:43:10a 94 inch reflector.
0:43:10 > 0:43:14The space telescope, of which we've got a model here,
0:43:14 > 0:43:18in the shuttle bay, is a complete satellite observatory.
0:43:18 > 0:43:22In other words, it will be able to do in space everything astronomers
0:43:22 > 0:43:25now do from large observatories on the surface of the Earth.
0:43:25 > 0:43:29The great advantage is that we get rid of the atmosphere.
0:43:29 > 0:43:32The atmosphere smears the images of everything that we see in sky,
0:43:32 > 0:43:35and we get a very hazy, blurred view of the universe.
0:43:35 > 0:43:38With the space telescope, we will get a ten times sharper picture,
0:43:38 > 0:43:41and converting that into terms of the improvement in distance
0:43:41 > 0:43:43with which we can see objects,
0:43:43 > 0:43:45we will see everything that we can now see in the universe,
0:43:45 > 0:43:48but at ten times greater distance than we can at present.
0:43:48 > 0:43:51In addition, we will open up other astronomical wavelengths
0:43:51 > 0:43:54which have never been explored before by cameras. For example,
0:43:54 > 0:43:58no-one has ever taken ultraviolet pictures of the deep universe.
0:43:58 > 0:44:01Equally, there will be the possibility of doing the same
0:44:01 > 0:44:02in the infrared waveband.
0:44:02 > 0:44:04When do you hope it'll be launched?
0:44:04 > 0:44:07It is expected it will be launched early in 1985.
0:44:07 > 0:44:09So you should be in time for Halley's Comet.
0:44:09 > 0:44:11This is one of the drivers behind the programme.
0:44:14 > 0:44:17Just about then, 1985,
0:44:17 > 0:44:21we'll be looking forward also to the next Voyager II pass.
0:44:21 > 0:44:25Remember, Voyager II is at this moment moving out from Saturn
0:44:25 > 0:44:27towards the next giant planet, Uranus.
0:44:27 > 0:44:30It should make its pass in January 1986,
0:44:30 > 0:44:34and send back the first close-range views of that strange green world
0:44:34 > 0:44:38with its thin rings, discovered as recently as 1977,
0:44:38 > 0:44:39and its strange axial tilt.
0:44:42 > 0:44:45Then on to Neptune, in August 1989,
0:44:45 > 0:44:48and Neptune's satellite, Triton.
0:44:48 > 0:44:50Leaving only Pluto not contacted.
0:44:57 > 0:45:01We began our programme at the Royal Greenwich Observatory,
0:45:01 > 0:45:04Herstmonceux, still the headquarters of British astronomy.
0:45:04 > 0:45:06And it seems only right to end here.
0:45:06 > 0:45:08I hope you've enjoyed our journey.
0:45:08 > 0:45:11It's taken us round the world in our pursuit of knowledge.
0:45:11 > 0:45:14Today, we are probing out to the depths of the universe,
0:45:14 > 0:45:16and every year we are solving new problems.
0:45:16 > 0:45:20Though each problem we solve seems to raise a whole host of others.
0:45:20 > 0:45:24I can't tell you what's going to happen during the next 25 years.
0:45:24 > 0:45:27Will there be bases on the moon?
0:45:27 > 0:45:29Can we find out once and for all
0:45:29 > 0:45:32whether the quasars really are immensely remote?
0:45:32 > 0:45:34And is there the slightest chance of our proving
0:45:34 > 0:45:37the existence of life on another world? I don't know.
0:45:37 > 0:45:39But one thing I can promise you.
0:45:39 > 0:45:43If I'm still alive in 25 years' time, in 2007,
0:45:43 > 0:45:48and if I'm still broadcasting, I'll still find plenty to say.
0:45:48 > 0:45:49Good night.
0:46:17 > 0:46:20Subtitles by Red Bee Media Ltd