A new book just arrived at the office, and I'm pretty jazzed about it because it covers a topic not often addressed — interpreting stellar spectra. Spectroscopy: The Key to the Stars by Keith Robinson (Springer, New York, 2007) is part of Sir Patrick Moore's Practical Astronomy series.
Spectroscopy, the study of stellar spectra, is astronomy's great tool. It's so far beyond photography for providing important information about celestial objects, they shouldn't be mentioned in the same sentence (oops!). By studying spectra, astronomers can tell what a star's made of, how hot it is, how fast it's moving toward or away from us, and lots more. Spectroscopy arrived on the scene a few decades before photography. For an historical account, I recommend 19th Century Spectroscopy: Development of the Understanding of Spectra, 1802–1897 by William McGucken (Johns Hopkins University Press, Baltimore, 1970). The book's a little tough to come by, but it's a great read.
OK, back to Robinson's book. Let me get my only gripe out of the way first, and it's a minor one: The label is a bit misleading. This book isn't a practical guide, it's a guide to the theory behind spectroscopy and what stellar spectra tell astronomers.
That said, if you ever wondered what the big deal is about spectroscopy or wished you understood it a little better (and aren't afraid of a little science), this book's for you. Robinson takes a step-by-step approach to spectroscopy, each chapter building on the ones before it. You can go as far into the book as you want, but the two chapters essential for amateur astronomers are "Stellar Spectra and That Famous Mnemonic" and "Glows in the Dark — Emission Lines and Nebulae."
This book covers some heady territory. Don't be surprised if you find yourself re-reading some sections. You may also encounter some unfamiliar terms: Robinson uses British spellings throughout, so, for example, readers in the United States will see "caesium" instead of the more common "cesium."
This book is a worthy addition to any advanced amateur astronomer's library. And, if you couple it with a truly practical book, Practical Amateur Spectroscopy by Stephen F. Tonkin (Springer, New York, 2002), you'll be able to do spectroscopy and understand it.