The Quiet Sun

Citation preview

N. Pushkov B. Silkin

THE QUIET SUN

MIR P U B L IS H E R S

H. B. nyUJKOB, B. M. CMJIKMH

BHMMAHME!

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N. V. PUSHKOV, B. I. SILKIN

THE QUIET SUN Translated from the Russian by George Yankovsky

MIR PUBLISHERS •

MOSCOW 196S

UDC 551.590.21 (023) =*20

How can events 150 million kilometres away affect us here on earth? But if you have ever complained of poor radio reception, if the compass needle has ever gone wrong, if you have ever wondered what has happened to the weather, the trouble most likely has to be sought at this great distance. Blame it all on the sun. This book is an account of that great world-wide undertaking— the International Quiet Sun Year— in which scientists of over 60 countries participated. Following the International Geophysical Year, it disclosed many secrets about our luminary. Everyone who wants to learn more about our sun and how it affects the planet we live on should read this book.

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CONTENTS

FROM S U N -W O R S H IP TO K N O W L E DG E

7

OUR OW N S T A R

12

A D ISC O V ER Y W ITH A ST R A N G E H IST O R Y

14

TH E PR O JE C T A N D IT S O U T LIN E

41

WE LIVE O N A N EN O R M O U S M A G N E T

56

W OR LD -W ID E M A G N ET IC SU R V E Y

94

EARTH CURRENTS

103

H E R A L D S FROM D IS T A N T W ORLDS

108

TH E IN V IS IB L E B E L T S O F T H E E A R T H

134

W H EN TH E SK Y IS ON FIR E

153

IN V ISIB L E C E L E ST IA L LIG H T

173

T H E IO N O SPH E R E

182

A T M O SPH E R IC S—C H ILD OF T H U N D E R ST O R M S

208

D O ES TH E S U N M A K E TH E W E A TH E R ?

212

G A LILEO : “ P R O V A N D O E R IP R O V A N D O ”

235

TH E F IN D IN G S OF TH E IQ SY AR E W HOLE W O R LD

239

O P E N TO THE

From sun-worship to knowledge ’ The Quiet Sun Year”. Isn’t there something oriental in the ring of this title? Like the “Year of the Dragon” in the calendar of the ancients, or perhaps the “Land of the Rising Sun”? Yet the International Quiet Sun Year, or IQSY for short, is not a poetic phrase but a rigorous term. It stands for one of the greatest scientific undertak­ ings. Let us take a fresh look at what seems to be quite an ordinary event. Every morning, as the dark of night fades away, a huge ball of fire bursts forth from the horizon lighting up the world about. A new day is born. This happens every 24 hours but still remains a miracle of na­ ture. Men have always felt it to be of the utmost significance; in remote ages man worshipped the forces of nature, and the most magnificent of them all—the Sun. Surely every people has passed through the stage of sun-worship. The primitive mind en­ dowed with preternatural powers the regular succession of day and night, the seasons and other celestial and terrestrial events associated with the sun. The principal deity of the ancient Egyptians was Ra, the life-giving god. Melkarth (Moloch) was the deity worshipped by the Phoenicians and Carthaginians To him human sacrifices were

made. The more humane Greeks and Romans of antiquity personified the sun as Phoebus, He­ lios, Apollo—the god of sunlight, music and poetry, the patron of the muses. The mighty AsSyrian and Babylonian god Shamash, the ancient Persian Mithras, and the cruel deity Kezalkoatl of the Mayas depicted as a winged serpent are all personifications of the sun, great in its wrath and in its mercy. The ancient Slavs would greet the spring sun, the joyous stormy god Yarila, with dancing and merrymaking. After a long winter Yarila would arrive on a white horse and in white raiment with a handful of wheat spikes and would bury the strawman embodying winter. Thus in all corners of the world have people carved the image of the sun, honoured it with merrymaking and singing of songs, and have built temples and worshipped it. Legends and myths were the first attempts to account for the unexplainable. Centuries passed before they gave way to knowledge based on facts. And, as always, the gain was not made without strife and sacrifice. Some time about the year 434 B.C., the an­ cient Greek thinker Anaxagoras first conjectured that the sun was not the god Apollo but a burn­ ing mass of rock. Anaxagoras even tried to work out its size. He figured our luminary to be of the dimensions of his home peninsula Peloponnesus, which is about a hundred kilometres across. He had no proofs of course, it was simply guesswork. The teaching of Anaxagoras was in conflict with the religious dogmas of the time. The philosopher was arrested, accused of sacrilege and his very life was at stake. 8

The followers of the great Pythagoras who lived in the fifth to fourth centuries B.C. (most famous among them was Philolaus) were much in advance of their times. They proposed a model of the world in which the earth rotated on its axis and revolved about some central body. True, at the centre they placed not the sun but rather a kind of mysterical central fire, around which moved the earth, the sun, the stars and the planets. Engels described Aristotle as the “most univer­ sal head” among the ancient Greek philosophers. Still and all, his enormous authority that held sway for over a thousand years did a very poor service to astronomers. Aristotle espoused the geo­ centric system according to which the earth was the fixed centre of the universe, while the stars, the sun and the planets were in revolution about it in concentric circles. What is more, Aristotle maintained that unlike the earth substratum, the celestial substratum, or the ether, was immutable, non-transient and immortal, and that all celestial bodies were perfect and devoid of any flaws. Scholars of the Middle Ages adhered to this the­ ory. With the spring of the Renaissance came a flowering of the arts and the trades, people set out on long voyages, a real interest in the sur­ rounding world burgeoned. January 7, 1610, was an historic day: Galileo Galilei trained his tele­ scope on the sky for the first time. The moon, planets and stars might be said to have been discovered anew. The surface of the moon was found to be not smooth as philosophers had been wont to say, but f n — 80?

9

rough with depressions and elevations in profu­ sion, the Milky Way was found to consist of an enormous number of stars invisible to the naked eye, and around Jupiter he saw four satellites in orbit. This was a forevision, as it were, of the “heretical” system of Copernicus, according to which the earth and other planets revolve about a central luminary, the sun. Galileo’s discoveries, which he published in The Sidereal Messenger, were like a thunderbolt from the blue. In the summer of that same year Galileo turned his telescope to the sun and found dark spots on its bright disk. This was nothing new. however, for they had been detected in naked-eye observations much earlier. The ancient Chinese chronicles of the II-IV centuries mention “flocks of birds” appearing on the disk of the sun. In Nikon’s Chronicle (Russia) for the year 1371 we read: “In that same summer there was a sign in the sun, spots that were black on the sun like nails. . .” Galileo needed only a few weeks of observa­ tion to disprove the commonlv held view that the spots were the shadow cast bv the planet Mer­ cury as it passed across the disk of the sun. The great Italian scientist carefully observed the spots for two years and came to the conclusion that the “spots are actual features on the surface of the sun, where they constantly appear and disappear, some in short intervals of time, others in longer intervals of time”. He noticed a constant movement of each of the spots from left to right (from the eastern to the western limb of the solar disk). Certain spots disappear from sight and then come into view again at the other limb after H>

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