137 P. Moore, The Sky at Night, DOI 10.1007/978-1-4419-6409-0_35, © Springer Science+Business Media, LLC 2010 For the first week of the New Year, several programmes on BBC2 were to commemorate the 400th anniversary of the first astronomical observations made with telescopes. The first of these programmes was the “Sky at Night”. We decided to look back at some of the telescopes we had visited since that first programme, way back in 1957. Various people were shown – in various locations – and we used extracts from the actual interviews. The earliest, I think, was with George Hole, for the 50th programme. We were down at Brighton, with George’s fine 24-in. reflector, hoping to give direct views of Jupiter and Saturn. Of course, it was “live” – everything was, in those days – so that we were at the mercy of the clouds. Five minutes before transmission, and 5 min late, the sky was brilliantly clear, but during the actual transmission cloud-cover was complete. As George said: “Totally obscured!” Chapter 35 Four Hundred Years of the Telescope Allan Chapman and myself on 15 February 2008 (Credit: Patrick Moore) 138 35 Four Hundred Years of the Telescope I introduced the programme from my observatory at Selsey. Among astronomers shown were Allan Chapman, Howard Bond, Kim Hermann, Peter Wehringer, Roger Angel, Pete Lawrence, Michael Barstow, Jeff Hoffman, Geoff Marcy, John Culshaw, Michelle Dougherty, Richard Ellis, and of course, Chris Lintott. Quite a galaxy – but it was a pity about those clouds… Who invented the telescope – and who first turned a telescope skyward? Most people would say “Galileo”, but they would be wrong. The first telescope about which we have definite information was made by a Dutchman, Lippershey, in 1608. Earlier reports coming from England are interesting, but not conclusive. Unfortunately for himself, Lippershey did not take prompt steps to establish priority, and other telescopes quickly appeared over Europe. Galileo obtained one during 1609, and “sparing neither trouble nor expanse”, as he put it, made one for himself. On July 26, 1609, came the first known astronomical observation made with a telescope; Thomas Harriot, one-time tutor to Sir Walter Raleigh, used his tiny “Dutch tube” to look at the crescent Moon and to marvel at the mountains, the valley, the craters, and the grey plains we still miss-call “seas”. Within a year or two, he had constructed a remarkably good map of the Moon. It was far better than any of Galileo’s lunar work, but he did little else astronomically, and it is Galileo who is rightly called the first true telescope observer. From January 1610, he made a series of spectacular discoveries, notably the four main satellites of Jupiter, the phases of Venus, spots on the Sun, and the “myriad stars” of the Milky Way. He even saw that there was something strange about the appearance of Saturn, though he could not make out its true nature. Galileo’s most powerful telescope magnified a mere 30 times, and was nothing like so effective as a pair of modern binoculars, quite apart from the fact that it had inconveniently small field of view. Its object-glass is convex, and the eyepiece lens is concave; a “Galilean” is bound to give a great deal of false colour. It was some time before this problem could be tackled, and although it is true to say that modern lenses give very little false colour, it would be wrong to claim that they give none at all. Isaac Newton never did solve the problem, which was one reason why he aban- doned refractors altogether and turned his attention to reflectors, building the first “Newtonian” 60 years after Galileo’s pioneering work. This certainly eliminated false colour, and a mirror is much easier to make thank a lens, but of course they have their disadvantages too. Reflectors can be temperamental, and requite regular servicing, which a refractor does not. For an early programme I did show Galileo’s telescope, and also Newton’s, but let me move on to the largest nineteenth century, the 72-in. reflector at Birr Castle, in Southern Ireland. It was homemade by the third Earl of Rosse, who had a lively interest in astronomy and is the supreme example of what my old friend Dr. Allan Chapman called a “grand amateur”. Lord Rosse wanted to build a telescope larger than any of its predecessors (at that time the record holder was Sir William Herschel’s 49-in. reflector) and, amazingly, he succeeded even though he had to 13935 Four Hundred Years of the Telescope make his own equipment and cast the huge metal mirror, an alloy of copper and tin – the casting process, vividly described by an onlooker, must have resembled a major display of pyrotechnics. The only assistants came from the Earl’s, and were workers trained by Lord Rosse specially for the purpose. The telescope was unwieldy and difficult to handle but it worked well, and was used to show the spiral structures we now know to be galaxies. It was, for some time, in a class of its own, but later in the century was overtaken by the new large refractors. For many years, it was out of action, but thankfully is now fully opera- tional again (I am proud to say that I had something to do with this). It remains unique in the history of science. Refractors were in vogue near the end of Victorian times, and almost all the largest telescopes of this kind were built before 1900 – notably the largest of all, the 40-in. at the Yerkes Observatory. This may be the useful limit, because an object-glass has to be supported round its edge, and if too heavy will distort under its own weight. A 49-in. was once made, but was a total failure, so that for Earth- based telescopes, at any rate, the Yerkes 40-in. is not likely to be surpassed. I admit that my own favourite is the 24-in. of the Lowell Observatory in Arizona, which I used a great deal in my pre-Apollo Moon-mapping days. There is one branch of observational amateur for which a refractor is far more suited than a reflector: solar work. Turn a Newtonian toward the Sun, and you are likely to cook your secondary. Heat is bad for mirrors, and also for eyepieces. Much the best way to study the solar surface is to use a refractor, and project the image on to a screen fixed behind the eye-end of the telescope. Moreover, adding H-alpha equipment is relatively easy with a refractor, the main problem being finance. Come back now to our historical story. After the large refractors we reach the twentieth century, and the dominance of single-mirrors. Glass, coated with a thin layer of silver or copper, took over from metal, and progress was amazingly rapid, due largely to George Ellery Hale, in America. Hale’s constant call was for “More light!” and he master-minded first a 60-in. and then, in 1917, a 100 in. both of which were set up on Mount Wilson in California. Hale was well aware of choosing sites with the best available seeing conditions, and this meant high altitude, above the thickest part of the Earth’s atmosphere. For three decades, the 100-in. reflector was in a class of its own, “spiral nebulae”, measuring their distances and proving the spirals were separate galaxies, far beyond our Milky Way. No other telescope of the time had sufficient power to make observations as delicate as this. The 100-in. remained the largest until 1948, with the completion of the 200-in. on Palomar Mountain (again planned by Hale, though sadly, he did not live to see it finished). The 200-in. was supreme for a while, and in 1952 enabled Walter Baade to show that the observable universe was twice as large as had been believed. But two major developments lay ahead. The larger mirror, the more difficult it is to make. Quite apart from this, these is the problem of our unsteady atmosphere. By the end of the war virtually all astro- nomical research was carried out photographically, so that images were blurred. New techniques, known as active optics and adaptive optics, reduced these effects very significantly. But even more important was the rise of electronics, and well 140 35 Four Hundred Years of the Telescope before the end of the twentieth century electronic devices had taken over from sensitive plates, just as photography had superseded visual observations a 100 years earlier. On my study wall, I have an image of Saturn taken with my 15-in. reflector a few weeks ago. It is far better than anything which could have been produced by the best professional observatory as recently as 1990. Electronic aids have made all the difference. The Palomar reflector is no longer the world’s largest, and is not even in the “top twenty”. Atop Mauna Kea in Hawaii, 14,000 ft above sea-level, you will find the Keck I and Keck II telescopes, each with a 100-m (387-in.) mirror and capable of working together. On Cerro Paranal, in the Atacama Desert of Northern Chile, is the VLT or Very Large Telescope, where each of the four components has an 8-m (630 in.) mirror. Together, they can pick up the light of the objects over 13,000 million light-years away – and remember, the universe as we know it is no more than 13.7 thousand million years old. These huge mirrors are not single, but segmented, i.e. made up of hundreds of individual parts fitted together to form the correct optical curve. There are of course space telescopes orbiting the Earth, so that seeing condition are perfect all the time, and no incoming radiations are blocked out by the Earth’s atmosphere. The 94-in. Hubble Space Telescope, launched by NASA in 1990, was the first; others have followed and have provided data impossible to obtain from ground level. We have indeed come a long way since Harriot had that first view of the crescent Moon through his time “Dutch tube”, 400 years ago. How far will we go during the next 400 years? Your guess is as good as mine! 141 P. Moore, The Sky at Night, DOI 10.1007/978-1-4419-6409-0_36, © Springer Science+Business Media, LLC 2010 Polar lights – Aurora Borealis in the northern hemisphere, Aurora Australis in the southern – have been known since early times; in Scotland, they were called the “Merry Dancers”, supernatural beings enjoying themselves in the heavens. To Eskimos, they represented a game of football played by spirits using a walrus-head as a ball. From England, they are not often seen really well; from higher latitudes, they are more frequent, and can be breathtakingly beautiful. For this programme Chris Lintott and Pete Lawrence went to Tromso in North Norway, and were rewarded with a brilliant display. Sadly, I could not go (I love Tromso), but back in Selsey I was joined by two researchers deeply involved in this work; Dr. Chris David, from the team STEREO (Solar Terrestrial Relations Observatory) and Professor Tony van Aiken, former Director of EISCAT (European Incoherent Scatter Scientific Association), which uses three radar systems in Chapter 36 The Merry Dancers Aurora (Credit: Peter Lawrence) 142 36 The Merry Dancers Scandinavia to study interactions between the Sun and the Earth as revealed by disturbances in the ionosphere and the magnetosphere. I first saw the Northern Lights in 1938 – not from Norway, but from my then home time, East Grinstead in Sussex. It was a beautifully clear winter evening and the whole sky was glowing a brilliant red. I wondered whether there could be a huge fire somewhere in Ashdown Forest, and it took me several minutes to realise that I was being treated to a brilliant display of aurora. After all, a Roman emperor, the much-maligned Tiberius, once made the same mistake when he sent his fire- fighters to quench what he thought was a huge blaze in the port of Ostia. After that display, I began to look up old stories and legends about the Lights. I found plenty of them. The nickname “Merrie Dancers” is Scottish; supernatural beings were cavorting about in the heavens – not always peacefully, because a red aurora showed that blood had been spilt. From Scotland aurorae are more frequent than they are south of the border. To some of the Eskimos, an aurora indicated a game of football played by spirits using a walrus-head as a ball (perhaps Reykjavik United versus Longyearbyen Town?) but in Siberia the tables were turned, where the walruses were the players and the ball was the human head. In Russia, the Lights were associated with the fire dragon Ognenniy Zmey, who approached women and seduced them while their husbands were away. There are legends everywhere. The Greenlanders believed that people who had passed on to the next stage of existence were signalling to their kinsfolk who were still on Earth. The Faroe Islanders kept their offspring indoors during displays, in case the Lights came down and singed their children’s hair, while in Estonia the aurorae were down virmalised, spirits from higher planes, sometimes friendly and sometimes not. To the Inuit of Alaska the Lights are people who have gone to the sky and are dancing to remind their loved ones that they are still around. The Finnish name for aurorae is revontulet, or sparks whisked upward when the Lapland foxes wagged their tails. The Sami people believed that the Lights (guovssahasat) could be dangerous, and might even descend and kill anyone who made fun of them. And in parts of Scandinavia it was said that the Lights were warlike Valkyries, “mounted upon horses and armed with helmets and spears…When they ride forth…their armour sheds a strange flickering light, making what men call the “aurora borealis (Thomas Bullfinch, 1855)”. There were more scientific explanations too. In Denmark and Sweden, it was believed that aurorae were due to volcanoes in the far north, put there to provide mankind with light and heat. The Inuit of Hudson’s Bay thought that the sky was a solid dome, and that the stars were holes letting through light from a shining background. But my favourite explanation is Norwegian; the Northern Lights are reflections in the sky cast of swarms of presumably luminous herrings swimming happily in the Arctic Ocean! Early astronomers had their own ideas. The Greek philosopher Anaxgoras (c. 500–428 bc) knew about aurorae, even though they are seldom seen from Greece, and attributed them to fiery vapour poured down in to the clouds above, while the Roman writer Se eca (5 bc–ad 65) put them down to currents of boiling at very high altitudes. Because the stars moved so quickly, they could emit enough 14336 The Merry Dancers heat to set them alight. The term “aurora” was coined by the French astronomer P. Gassendi in 1621, and the first scientifically accurate account was written in 1650 by K. Gesner of Zurich. It is not true that aurorae are the best seen from the North Pole – far from it. The electrified particles from the Sun do make for the north magnetic pole, but are captured by the Earth’s magnetic field, and the most favourable observing site are in the “auroral oval”, a belt centred on the magnetic pole. Generally, the Oval remains north of England and brushes Scotland, but during a solar storm it may broaden sufficiently to cover the whole of the British Isles. I have hunted aurorae in Hudson’s Bay, Alaska, Finland and Norway, but I have had my best views from Tromso in North Norway, which is why I took “Sky at Night” viewers on trips there, though I admit that I was influenced by the fact. 145 P. Moore, The Sky at Night, DOI 10.1007/978-1-4419-6409-0_37, © Springer Science+Business Media, LLC 2010 At the time of this programme, Saturn was in Leo at opposition and thus well place observation. The rings were edgewise-on, so that the planet was temporarily shorn of its beauty, but to make up for this, there was a great opportunity to watch the satellites. Two were very much in the news: Enceladus. With its icy fountains, and Titan, with its chemical lakes. The Huygens space craft, still orbiting Saturn and Chapter 37 The Fountains of Enceladus Fountains of Enceladus (Credit: NASA) [...]... ago Once they separated, safely away from Earth, Herschel and Planck said good-bye rather than adieu, because they will never meet again By 2013, both will have ended their active careers, but they will have given us new insight into the nature of the great universe around us Chapter 39 Onward to the Moon With Neil Armstrong; photo with my film camera! Man reached the Moon in July 196 9; for the 40th... Dixon, put us “on air” at a time when more people retired for the night After all, why should he regard a mere Moon landing as more significant than a soap opera or a quiz? P Moore, The Sky at Night, DOI 10.1007 /97 8-1-44 19- 64 09- 0_ 39, © Springer Science+Business Media, LLC 2010 153 154 39 Onward to the Moon Nobody who has ever looked at the Moon can have failed to see the dark patches once believed to... football fields They have been called “hot”; at a temperature of 9 90 °C, this does not sound inviting, but the general temperature of the surface is a chilling −200°C There are no observed geysers or tiger stripes away from the south polar region, and spectroscopic analysis show that, as expected, the crystals are of 37 The Fountains of Enceladus 147 o rdinary water ice There is no escape from the conclusion... Point, a stable point beyond the Earth’s orbit where a body will have the same orbital period as the Earth The main advantage of the L2 point is that it is isolated, and therefore not affected by radiations from Earth, either natural or man-made Herschel did not start his journey alone With it was Planck, designed to study the CMB or Cosmic Microwave Background – the aftermath of the Big Bang, 13.7 thousand... But…they do! Chapter 38 The Herschel Telescope The Herschel Telescope (Credit: Arianespace ESA) P Moore, The Sky at Night, DOI 10.1007 /97 8-1-44 19- 64 09- 0_38, © Springer Science+Business Media, LLC 2010 1 49 150 38 The Herschel Telescope Following the successful launch of the Keper mission, two more major missions were planned: Herschel and Planck For our April programme, we concentrated on Herschel, and... developed equipment capable of observing them The particles gushed are certainly responsible for the existence of the E ring, which is incredibly tenuous but which extends from the orbit of Enceladus out to well beyond the orbit of Dione, the fourth of Saturn’s principal satellites Moreover, the geysers must be “feeding” the ring all the time The vents from which the geysers issue are not large, and in... enough, but later discoveries made the situation even odder Near the south pole there were streaky features nicknamed “tiger stripes”, which turned out to be deep surface cracks, and there were indications of an atmosphere It was extremely thin, but it was a major surprise The gravitational pull of Enceladus is so weak that it would not be expected to hold down any atmosphere at all Michelle Dougherty had... the Sun, and realised that there were radiations beyond the red end of the rainbow band He called them “black light.” We know them as infra-red Stars are born in dusty regions, so that the actual processes of star formation are hidden in visual light Infra-red comes to the rescue, and Herschel will be particularly valuable because it will look into the far infra-red beyond the range of its predecessors... means that the telescope must have a limited lifetime, because the liquid helium will be exhausted in less than 5 years and the thin mirror, with its f/0.5 focal ratio, will become too warm to operate The obvious question is: Why not re-fill the liquid helium tank? Answer: Because Herschel will be too far away Unlike Hubble, it is not orbiting the Earth, but is orbiting the Sun at what is called the L2... before the end of 1603, for the excellent reason that this was the year in which Gilbert died It shows several of the “seas” in ecognisable form, so that it did at least make a start in lunar cartography r Then came the invention of the telescope, by Dutch optical workers – not by Galileo, as is popularly believed Neither was Galileo first to turn a telescope Moonward That distinction goes to the English . on trips there, though I admit that I was influenced by the fact. 145 P. Moore, The Sky at Night, DOI 10.1007 /97 8-1-44 19- 64 09- 0_37, © Springer Science+Business Media, LLC 2010 At the time of. of the first astronomical observations made with telescopes. The first of these programmes was the Sky at Night . We decided to look back at some of the telescopes we had visited since that. Moore, The Sky at Night, DOI 10.1007 /97 8-1-44 19- 64 09- 0_35, © Springer Science+Business Media, LLC 2010 For the first week of the New Year, several programmes on BBC2 were to commemorate the 400th