Jupiter

192 Pages·2018·39.47 MB·English

by  William Sheehan

jupiter
Kosmos
A series exploring our expanding knowledge
of the cosmos through science and technology
and investigating historical, contemporary
and future developments as well as providing
guidance for all those interested in astronomy.
Series Editor: Peter Morris
Already published:
Jupiter William Sheehan and Thomas Hockey
The Moon Bill Leatherbarrow
The Sun Leon Golub and Jay M. Pasachoff
Jupiter
William Sheehan
and Thomas Hockey

reaktion books
To John Rogers (W. S.)
To Reta Beebe (T. H.)
Published by Reaktion Books Ltd
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London n1 7ux, uk
www.reaktionbooks.co.uk
First published 2018
Copyright © William Sheehan and Thomas Hockey 2018
All rights reserved
No part of this publication may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronic, mechanical, photocopying,
recording or otherwise, without the prior permission of the publishers
Printed and bound in China by 1010 Printing International Ltd
A catalogue record for this book is available from the British Library
isbn 978 1 78023 908 8
contents
Prologue 7
1 The Jovian Planets 15
2 Jupiter: A Primer for a Giant Planet 34
3 Superficial Matters 46
4 Atmospherics 51
5 The Great Red Spot Becomes Great 63
6 A Bewildering Phantasmagoria: Jovian Meteorology 94
7 Above Jupiter 113
8 Jupiter in Collision 141
9 Juno to Jupiter 153
10 Observing Jupiter 161
appendix i: Jupiter by the Numbers 169
appendix ii: Conjunctions of Jupiter 172
appendix iii: The Galilean Satellites by the
Numbers 174
appendix iv: Space Probes to Jupiter 175
Glossary 177
References 179
Acknowledgements 183
Photo Acknowledgements 185
Index 187
One of the best pictures of Jupiter obtained from the Earth, by the doyen of amateur planetary imagers, Damian Peach. Peach
used an asi 174-mm camera on a 1-m Cassegrain located near Cerro Pachon, Chile, that he operated remotely from his home
in Hamble, Hampshire, England.
Prologue
To the naked eye, Venus is brighter, while Mars, which appears
like a red-hot coal round the times of its every-other-year oppos -
itions, is more dramatic. But Jupiter, even to the naked eye, is still
the grandest of all the planets. It shines with a majestic steady mien
and is conspicuous for about ten of the thirteen months that elapse
between its successive conjunctions with the Sun. (For about three
months of each of these thirteen, it is lost in the solar glare as it
passes behind the Sun.) It has inspired more poetic utterances than
any other planet, with the single exception of Venus, the beautiful
Morning and Evening Star. William Wordsworth beautifully invokes
Jupiter in the Prelude, Book iv (1850):
A pensive feeling spread far and wide:
The trees, the mountains shared it, and the brooks.
The stars of heaven, now seen in their old haunts –
White Sirius glittering o’er the southern crags,
Orion with his belt, and those fair seven,
Acquaintances of every little child,
And Jupiter, my own beloved star.
Walt Whitman also invokes its majestic calming presence in
‘On the Beach at Night’, from Leaves of Grass (1881–2):
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jupiter
On the beach at night,
Stands a child with her father,
Watching the east, the autumn sky.
Up through the darkness,
While ravening clouds, the buried
Clouds, in black masses spreading,
Lower sullen and fast athwart and down the sky,
Amid a transparent clear belt of ether
Yet left in the east,
Ascends large and calm the lord-star Jupiter,
And nigh at hand, only a very little above,
Swim the delicate stars the Pleiades.
The planet has evoked such feelings as far back as we have
records, for it was no less than the ‘beloved star’ of the first serious
observers of the planets, the ancient Sumerians and Babylonians.
Three thousand years ago they admired its beauty and calm grand-
eur as it stood in the mid-heavens, regal and untroubled above the
gathering clouds in the east. And they too named it ‘lord-star’.
The Sumerians and Babylonians did not regard the planets as
gods as many other early peoples, including the Greeks, did. Instead
they saw them as manifestations, interpreters; they were the ‘stars
of the great gods who ruled the world’. Their wanderings among
the background stars, reversals of direction and conjunctions – the
other planets and prominent stars were viewed as omens providing
a cryptic commentary on terrestrial affairs. Many of these omens
were collected in the so-called ‘Enuma Anu Enlil’ tablets, a series
of seventy tablets containing thousands of omens dating back to
the second millennium bce. The name ‘Enuma Anu Enlil’ means
‘when Anu and Enlil . . .’, the opening words of the first tablet. Anu
and Enlil were Sumerian gods while the chief god of the Babylonian
pantheon was Marduk (associated with Jupiter). The following
is typical of the omens: ‘If Marduk [rises] in the path of the [god
8
prologue
The famous ziggurat at
Ur in Mesopotamia. In the
background shines the
Star of Marduk, the chief
Babylonian god. Painting
by Julian Baum, 2009.
Enlil’s] stars, the king of Akkad will become strong and [overthrow]
his enemies in all lands in battle.’1
Much later, in China in the fourth century bce, the astrologer
Gan De compiled Suixing Jing (A Canon of the Planet Jupiter), now
lost. The Chinese name for the planet was Muxing. As Marduk had
been for the Babylonians, Muxing was for the Chinese: the head of
all the host of heaven.
Gan De had a close associate, Shi Shen, and together they pro-
duced a star catalogue, some two centuries before the famous star
catalogue of the Greek astronomer Hipparchus. (Earlier Babylonian
star catalogues exist but the authors are anonymous.) Though the
Chinese were especially interested in Jupiter, they made accurate
observations of the other planets as well, and worked out their
sidereal and synodic periods. These periods are still fundamental in
astronomy and are needed for planning observations of the planets.
The synodic period is the time a planet takes to return to the
same position on the celestial sphere relative to the Sun. The word
comes from the Greek synod, which means a meeting or gathering.
This term is well known in connection with ecclesiastical assemblies
9