xvii
Preface
is is a little book about a big subject, and it began as an art exhibit. Astronomy: Images, Ideas
and Perspectives, a collaborative effort between Judith Baker Waller (Professor of Art at the Fox
Cities campus of University of Wisconsin Oshkosh) and myself, premiered in Waupaca, WI in
2000. As part of the preparation for the exhibition, I sat in on Judith’s art history class. But I also
began writing—for her—a description of key concepts in astronomy and cosmology. My goal
was not so much to write a text that would be understandable to an artist. Rather, I wanted my
text to be useful for Judith’s making of art. And so I hit upon the idea of describing astronomy
in terms of grand themes—space, time, evolution, etc. As I began to synthesize basic astronomy
in these terms, I realized that I had much to learn, and that this might be a useful perspective
for anyone.
I have divided the material in this book into five complementary and parallel tracks. Each
can be seen as a brief description of astronomy and cosmology as a whole, but from only one
limited perspective. To fully understand one track, one must understand the others; but each
track is written to be as stand-alone as possible. ese five STEPS are as follows.
1. Space: What are the sizes of, and the distances between, the various things that make up
our universe? As an example, how does the size of the Earth compare to its distance from
the sun? And how does this compare to the size of the sun, a fairly typical star?
2. Time: How has the universe as a whole changed, and what is its future? As an example
of just one part of this history, when—in the overall scheme of things—did stars like the
sun first begin to form?
3. Evolution: How do different parts of the universe change? For example, how does an
individual star like the sun change over time?
4. Process: What are the basic building blocks and rules of interaction that govern what goes
on in the universe? For example, what are the forces that keep a star like the sun round?
5. Structure: What makes up what? For example, what larger structures can a star be part
of?
Many topics are covered in each of these tracks; you will read about stars, for example, in
each of the five sections. But in each track you will read about stars from a different perspective.
e same holds for galaxies, planets, supernovae, and clouds of interstellar gas. e goal is that
the reader will gradually synthesize the material into a “big picture,” building an image of not
xviii PREFACE
only the different parts that make up our universe, but also how they fit together and interact
with each other.
e Big Picture can be used as the foundation for an introductory undergraduate survey of
astronomy course. But as the sole basis for such a course this book is incomplete, and intentionally
so. e reader will find here, for example, no descriptions of eclipses or phases of the moon. And
so e Big Picture is not intended to be comprehensive; rather, I have included topics only insofar
as they directly contribute to an understanding of the five STEPS. It is my contention, however,
that most of the obviously left-out topics are perfect for student assignments or projects; excellent
surveys of eclipses, for example, are widely available online.
John Beaver
December 2019
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