Galaxies: A Very Short Introduction
John Gribbin
Oxford University Press
978-0199234349
Galaxies was my second Very Short Introduction on astronomy, and I found it to be more of a challenge than the first. In fact I had to read it twice in order to get my head around some of the concepts. The book was rather inconsistent when it came to explaining astronomical terms and concepts—some are explained in the text, some are defined in the glossary, but others are not explained at all—and this made it hard to follow some of the discussion. I’ve filled some of the gaps serendipitously in the course of listening to the very entertaining 365 Days of Astronomy podcast daily, but it shouldn’t have to come to that with a book that purports to be an introduction for the average reader.
I did learn quite a lot from the book in spite of the occasional difficulties. The first section covers the history of the study of galaxies which is very recent, since it takes a powerful telescope to distinguish the individual stars in a galaxy. It was not until the 1920s that Edwin Hubble, working with the largest telescope yet built, established that previously observed nebulae are not clouds of gas but clouds of stars, and that our galaxy is not the only one in the Universe. Indeed astronomers now estimate that there are hundreds of billions of galaxies in the Universe, each of which can contain hundreds of billions of stars.
I’ll just let that sink in for a moment…
OK. Although the book does cover the development, structure, distribution, and dynamics of galaxies, most of it is really about what we have learned about the Universe from studying galaxies. I won’t go into detail here (and I’m not sure I could explain it anyway), but the study of galaxies has led to profound discoveries about the nature of the Universe. It’s a perfect example of how studying one thing in detail can contribute greatly to a better understanding of something much greater. However, I think the book dwelt on the subject too long, at the expense of describing galaxies themselves in more detail, and perhaps straying into the territory of Cosmology: A Very Short Introduction, my next astronomy book. I look forward to that book filling in more of the gaps in my understanding of what we know about this astounding Universe of ours.
Hubble Ultra Deep Field: This is what they saw when they pointed the Hubble Space Telescope at an “empty” patch of sky: over 10,000 galaxies never seen before.
