A History of Astronomy from 1890 to the Present David Leverington A HISTORY OF ASTRONOMY from 1890 to the Present Springer London Berlin Heidelberg New York Paris Tokyo Hong Kong Barcelona Budapest Front cover: The Great Vienna Telescope made by Howard Grubb of Dublin in 1880 with a 27 inch (69 cm) diameter objective For five years it was the largest refractor in the world The picture of the Hubble Space Telescope is reproduced by courtesy of NASA ISBN-13: 978-3-540-19915-1 e-ISBN-13: 978-1-4471-2124-4 DOl: 10.1007/978-1-4471-2124-4 British Library Cataloguing in Publication Data Leverington, David History of Astronomy: From 1890 to the Present Title 520.904 Library of Congress Cataloging-in-Publication Data Leverington, David, 1941A history of astronomy from 1890 to the present / David Leverington p cm Includes bibliographical references (p ) and index (pbk : alk paper) Astronomy-History-20th century I Title QB22.L481995 520'.9'04-dc20 95-12034 © Springer-Verlag London Limited 1995 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency Enquiries concerning reproduction outside those terms should be sent to the publishers Contents Preface ix Introduction xi • The Sun Early Work The Temperature of the Sun and its Generation of Energy The Corona Sunspots and the Disturbed Sun The Quiet Sun and the Interplanetary Plasma The Solar Constant The Solar Spectrum 11 15 18 22 • The Moon 23 Early Work The Surface The Origin and Subsequent History of the Moon 23 26 29 • The Origin of the Solar System 31 Early Theories Collisions and Close Encounters Condensing Nebulae Re-examined 31 33 35 • The Terrestrial Planets 37 Mercury Venus The Earth Mars 37 42 46 53 • The Gas Giants 62 Jupiter Saturn 62 71 Uranus Neptune 80 87 • Small Bodies of the Solar System 96 Pluto 96 The Asteroids 103 Comets 109 Meteorites 118 • Stellar Evolution and Stellar Structures 120 Early Work The Luminosity of Stars The Harvard Classification Initial Evolutionary Ideas Ionisation and the Abundance of Hydrogen in Stellar Atmospheres The Surface Temperature of Stars The Internal Structure of Stars The Source of Energy in Stars The MKK and BCD Classification Systems Later Evolutionary Ideas Stellar Populations 120 125 126 128 133 135 136 141 145 148 152 • Variable and Double Stars 154 Early Work Short Period Variables Long Period Variables Irregular Variables Flare Stars Eclipsing Binaries Non-Eclipsing Binaries 154 159 162 163 164 165 169 • Young Stars, Old Stars and Stellar Explosions 171 Young Stars Pulsars Novae and Supernovae Black Holes 171 173 178 204 10 • The Milky Way 208 Early Work Dimensions and Structure The Interstellar Medium Nebulae in the Milky Way vi 208 211 221 226 11 • Galaxies 230 The Nature and Distance of Spiral Nebulae Red Shifts Quasars Dwarf Galaxies Galactic Evolution 230 236 237 246 247 12 • Cosmology 252 Early Cosmological Theories Revisions to the Hubble Constant The Microwave Background Radiation The Missing Mass 252 253 256 257 13 • Optical Telescopes and Observatories 259 Early Telescopes Early Observatories The Transition to Reflectors The Harvard College Observatory Mount Wilson Palomar Mountain and the 200 inch Schmidt Telescopes South Africa Kitt Peak The Multi-Mirror Telescope Mauna Kea La Palma The Anglo-Australian Observatory The European Southern Observatory 259 261 263 264 267 270 272 273 274 275 276 278 279 280 14 • Tools and Techniques 283 Photography Spectroscopy Photometry Other Tools and Techniques 283 290 296 304 15 • Radio Astronomy 310 Early Radio Astronomy 310 Radio Telescopes 314 16 • Space Research 320 Introduction Results from Early Sounding Rockets Sputniks and the Formation of NASA The Race to the Moon Early Solar Plasma Research vii 320 320 322 324 326 Missions to the Terrestrial Planets Pioneers 10 and 11 Voyagers and The Halley Intercepts Orbital Observatories 327 331 333 339 341 17 • Modern Astronomy in Context 355 Introduction 1890-1914 1914-1939 : 1939-1970 1970 to the Present 355 355 356 357 358 References and Further Reading Units General Abbreviations Used The Greek Alphabet Subject Index Name Index 361 viii 364 366 367 369 379 Preface The history of astronomy is, like most history, a multidimensional story, and when writing about a specific period, the author has to decide how to handle all the developments of earlier times in order to set the scene I have done this by starting most chapters of the book with a summary of astronomical knowledge at the beginning of our chosen period, together with a brief review of how such knowledge had been gained This story is not only interesting in itself, but it will also assist those readers that would appreciate a brief reminder of some of the basic elements of astronomy It is also necessary to decide when to start our history Should it be the year 1900 or 1890, or should it be linked to some key development or investigation, e.g the discovery of the electron by J J Thomson in 1897, or the discovery of spectroscopic binary stars by Pickering and Vogel (independently) in 1889, or maybe the year 1890 in which Thomas Edison tried unsuccessfully to detect radio waves from the Sun and Johannes Rydberg published his formula for atomic spectra? I have, in fact, decided to start this history at about 1890, as it was the year of publication of the Draper Memorial Catalogue of stellar spectra which, together with its updates, provided essential data for the understanding of stellar spectra until well into the twentieth century This date also gives a clear hundred years up to the present As astronomy is such an enormous subject, I have described progress in each of the main subject areas of the Solar System, the Stars and the Galaxies sequentially, rather than try to paint the developing picture in all these areas together Then follow parts on the development of Instruments, Facilities and Techniques mainly in the guise of Telescopes, Radio Astronomy and Space Research It is not practical, in one volume, to describe all the developments in astronomy over the last one hundred years, and so some selection of material is inevitable My aim is to give an outline of developments, and enable those who wish to investigate the subject further, to so by consulting the books listed at the end This book is written for the reader with a basic understanding of astronomy, but if I have failed to convey the story clearly enough in some areas, I would be grateful to receive any suggestions for improvement I would like to express my special thanks and appreciation to Alan Cooper, Roger Emery, Mike Inglis and Stuart Clark who had the kindness and patience to read the text and suggest modifications of both fact and style, to make the book more accurate and readable If there are any errors of fact, misinterpretation or misrepresentation remaining, however, they are entirely mine and I apologise in advance Finally, in any project of this nature, the pressure does not stop with the writer, and this book would not have been completed except for the patience and encouragement of my wife Chris She deserves an extra vote of thanks, for putting up with me and piles of books and papers all over the house, during the time that it has taken to turn this book into a reality x Introduction Astronomy is the oldest and most fundamental science It attempts to explain not only what the Universe is today and how it works, but also how it started (if indeed there was a starting point), how it evolved to the present day and how it will develop in the future Astronomy is also about a Universe that can be seen, free of charge, by anyone who cares to glance at the night sky, weather and light pollution permitting Can anyone looking at a really dark sky, girdled by the Milky Way, not be impressed by what he sees, and wonder how we on our small insignificant planet fit into all of this? For many centuries man has observed the heavens and has tried to explain what he sees To us, with the benefit of hindsight, a great many of the explanations are obvious, but in the past, many excellent astronomers have held ideas which seemed logical to them, but now seem strange to us For example, William Herschel, one of the greatest astronomers of all time, believed, at the end of the eighteenth century, that the surface of the Sun was dark underneath its bright atmosphere, and that it could be inhabited by living beings It was only in the mid nineteenth century that it was realised that the Sun was gaseous throughout, and it required the advent of atomic physics in the twentieth century to explain how the Sun generates its heat There is no reason why many of our own theories should not be inaccurate, or even wrong, of course, and it is interesting to speculate how our knowledge of today may appear in time to come Will the Big Bang theory have been abandoned, and will black holes have been shown to be just a figment of our imagination? Most astronomers think not, but who knows? The twentieth century, for so long synonymous with progress and modern thinking, has but a short way to go before it becomes the last century It seems an appropriate time, therefore, to review what has happened in the science of astronomy over the last hundred years or so A period in which travel and communications, for example, have been revolutionised by scientific discoveries and ... courtesy of NASA ISBN-13: 97 8-3 -5 4 0-1 991 5-1 e-ISBN-13: 97 8-1 -4 47 1-2 12 4-4 DOl: 10.1007/97 8-1 -4 47 1-2 12 4-4 British Library Cataloguing in Publication Data Leverington, David History of Astronomy: From 1890. .. both the variability of the Earth's atmosphere and the poor accuracy of the radiometers available at the time Little progress was made in measuring variations in the solar constant until it became... increase it, and he tried to use data on sunspot and faculae variabilities to try to correlate them with solar flux variations Foukal, Pamela Mack and Jorge Vernazza analysed the old Smithsonian