J. McEvoy - Eclipse - The science and history of nature's most spectacular phenomenon

William Collins

An imprint of HarperCollins Publishers Ltd. 1 London Bridge Street Lodnon SE1 9GF

www.harpercollins.co.uk

Copyright © J. P. McEvoy 1999

First published in Great Britain in 1999 by Fourth Estate Limited

Every effort has been made to contact copyright holders for permission. Any omissions or errors will be corrected in future editions.

Designed by Robert Updegraff

Illustrations by Mark McEvoy

The right of J. P. McEvoy to be identified as the author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

A catalogue record for this book is available from the British Library

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Source ISBN 9781841151847

Ebook Edition © MARCH 2017 ISBN: 9780007480302

Version: 2017-03-01

For Emily, Muirenn, Joel

and the baby arriving with the eclipse

in August 1999

Cover

Title Page

Copyright

Dedication

Prologue

Understanding an Eclipse

The Babylonians, Chroniclers of Eclipses

The Saros Cycle: the 6585-Day Coincidence

Ancient Predictions of Eclipses: Controversies

Tracking a Solar Eclipse

The Sun’s Surface: Victorian Solar Eclipses

Confirming General Relativity

The Last Eclipse of the Millennium

Glossary

Further Reading

Acknowledgements

Index

Other Books By

About the Publisher

Stretching over 1,300 km south of the California state line between San Diego and Tijuana is a peninsula of mountains, deserts and plains ending at one of the most beautiful beaches in the world. Fine golden sand for miles and miles slopes into the azure Sea of Cortés and the Pacific Ocean. The peninsula, called Baja California, is actually part of Mexico. In the heat of the summer of 1991 I arrived, planning to view my first total eclipse of the Sun.

The morning of 11 August is bright and clear. Amid the palm trees and cactus plants all along the beach, tripods are being set up in the sand, an army of straw hats and Bermuda shorts appear as far as the eye can see. Everyone is buoyant. Not a single cloud in the sky, though still a few hours to go. Totality would be unusually long today at Los Cabos, 6 minutes 26 seconds, close to the theoretical maximum for a solar eclipse. The Moon’s shadow, when it reaches Baja, will be 260 km wide, moving along the beach at a speed of about 40 km per minute. As the bell in the small church tolls 10:00 a.m., the crowd makes final adjustments to telescopes and cameras. The long wait is over. Twenty-three minutes to go.

First contact occurs at 10:23:17 as the Moon’s disk just touches the Sun’s. The sky continues to be cloudless and no one is thinking of the weather. The show has begun.

In earlier times humanity held its breath during this solar disappearing act, offering sacrifices to appease the evil spirits who might destroy humanity’s source of heat and life itself. Slowly the Moon cuts deeper and deeper into the Suns image and it is now obvious that the two disks have the same diameter, a remarkable coincidence. The light fades imperceptibly.