Cecilia Payne-Gaposchkin: Introduction to Astronomy

Cecilia Payne-Gaposchkin published Introduction to astronomy in 1964. This book has great significance for me [EFR] since I bought it when I was a student in the early 1960s. I still have my copy and below is an extract from the Preface and from the Introduction:

1. Preface

This book is intended to introduce the elements of astronomy to the student and to the general reader who may have little background to mathematics or physics.

My chief reason for writing the book was a desire to give emphasis to stars and stellar systems as well as to the solar system, which usually occupies the major part of an elementary book. The greater part of modern astronomy is concerned with stars, and even an introductory text should reflect this emphasis.

I hope that this book will serve the purpose, among other things, of introducing astronomy to the liberal arts student who is "fulfilling a science requirement." With this in mind, I have been at pains to point out associations with the fields of language, literature, and history. Astronomy has played no small part in the cultural development of the human race.

2. Introduction: The Dawn of Astronomy

When Science from Creation's face
Enchantment's veil withdraws,
What lovely visions yield their place
To cold material laws!
Who has not experienced the mysterious thrill of springtime in a forest, with sunbeams flickering through the foliage, and the low humming of insect life? It is the feeling of unity with nature, which is the counterpart of the attitude of the scientist, analysing the sunbeams into light quanta and the soft rustlings of the dragon-fly into condensations and rarefactions of the air. But what is lost in fleeting sentiment is more than regained in the feeling of intellectual security afforded by the scientific attitude, which may grow into a trusting devotion, challenging the peace of the religious mystic. For in the majestic growth of science, analytical in its experimental groping for detail, synthetic in its sweeping generalizations, we are watching at least one aspect of the human mind, which may be believed to have a future of dizzy heights and nearly unlimited perfectibility.
Theoretical Astrophysics (Introduction)

Astronomy is certainly the oldest, yet perhaps the simplest, of the sciences. In a way it contains the broad generalization of all physical science, for it spans conditions wider than can be produced on earth. It has

... such large discourse,
Looking before and after ...
that the astronomical scale of time is reckoned, not in centuries or millenniums (thousands of years), but in hundreds of millions of years.

Science is not a form of magic, popular opinion to the contrary. Magic was, perhaps, its ancestor, in the days when man personified the phenomena of nature as gods to be feared and placated. But as knowledge grew, the world was found to be predictable. A calendar could be drawn up to foretell the rhythm of the seasons. A still further step revealed that the world can be analysed, and some phenomena controlled: science and technology were born.

Neither is science a system of mere technical description. Most of its concepts can be expressed in simple, everyday language. But such statements, if they are to be both correct and comprehensible, are apt to be lengthy. Science uses technical words and symbols to save time and to be definite. An idea can often be expressed more briefly and more clearly in symbols than in words.

For example, contrast the statement that "the sum of two numbers, when multiplied by itself, is equal to the sum of the first number multiplied by itself, the second number multiplied by itself, and twice the number obtained by multiplying the two numbers together" with the statement,

(a + b)2 = a2 + 2ab + b2.
The advantage of the shorthand symbolic expression should be obvious. Again, consider how much time is saved by expressing "the point in a planet's orbit where it is furthest from the sun" by the single word "aphelion." Our everyday language is actually permeated by shorthand technical terms (fuse, radio tube, accelerator). Science uses a technical vocabulary to save both time and confusion. But this vocabulary is a means, not an end. We should never make the mistake of supposing that a technical expression is an explanation; it is nothing but a label.

Even astronomy, remote as it appears to be from everyday life, has practical applications to navigation, surveying, and the firing of projectiles. But from the human point of view, its greatest importance lies in its cultural influence. Astronomy first revealed to man the existence of natural law, and development of the science has steadily broadened our horizons.

To primitive man, the earth was the centre of the universe. Gradually our planet emerged as but one of many that circle the sun; the sun assumed the central role. Further widening of the horizon revealed that the sun is but one star among many, and that other stars may rival or excel our own sun in size and brilliance. At first the system of stars was pictured as arranged around the sun, but as knowledge accumulated, the sun itself, with many other stars, was found to be moving in a huge orbit about a distant centre. Our system of stars is itself a gigantic, rotating body, isolated in space. A further expansion of our horizon revealed that our stellar system (a galaxy) does not fill the whole universe. Millions of essentially similar, widely separated stellar systems populate space. True, our own is one of the largest, but it is in no way unique. Nor does it appear to occupy a favoured position in the universe. The advance of astronomical knowledge has successively dethroned the earth, the sun, and the stellar system from their supposed unique and central stations.

JOC/EFR November 2017

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