The community of serious amateur astronomers had been waiting for a good technical reference on double stars. Despite some books have been written about the subject (such as the classic "The Binary Stars“ by Robert Aitken), they are all out of print nowadays and are really hard to find second-hand.

"Observing and Measuring Visual Double Stars" is an excellent collection of papers from several authors that offer an in-depth perspective of every aspect of observational astronomy on double stars. The book seems to be organized in three areas: The first one is a very good introduction to visual double stars, discussing issues such as why to observe double stars, what can be done with binoculars, theories of double star formation, double stars and planets, and completed with a very well structured scale of binary systems from the point of view of time consumed in orbiting periods. The authors don't forget to comment some hypothesis about our Sun being part of a double system.

The second part of the book is more technical in nature, offering excellent discussion on the concept of resolution in telescopes and the issue of using reflecting telescopes for studying double stars. Then, it immediately goes about measuring techniques and what type of measuring devices are available, ranging from Double-Image to Diffraction Grating and then Filar Micrometers and Reticled Eyepieces, but not forgetting some other powerful techniques such as CCD imaging and Speckle Interferometry for the amateur.

Specially bright are two chapters devoted to calculate the orbital elements of a double star and then its orbit, although a more detailed written discussion about the relationship between the inclination of the real double's orbit plane against the observed plane and the shift between theoretical and observed foci in the orbit's ellipse is missed. All the needed mathematical formalism is clearly exposed, but some added comments about this issue would have been very well welcomed.

The third section of the book supplies lots of complementary information and very useful advice to the amateur, telling him/her how he/she can contribute, how to prepare and publish results (measures) of observing sessions while also introducing the reader to some active double stars observers all over the world. Last, but no least, the book includes a CD with tons of data, including the complete Washington Double Star Catalogue and many useful computer programs that will help the double star aficionado to crunch the numbers arising from observing doubles. 

Many amateur double star observers measure these nice celestial objects, obtaining position angles and distances between the double's components, but not all of them know exactly why they measure. From the first pages of the book, the authors correctly state that the goal of measuring doubles is to calculate the mass of stars. After obtaining the orbit of a double star, and if the distance to the system is known, then it's possible to calculate the mass of both components in a double (this is not the only method; studies of spectroscopic, eclipsing binaries, provide mass of stars without knowing the distance to them). What the book doesn't mention is the final reason for calculating masses for stars. As every astronomer knows, every major feature of a star (luminosity, temperature, age and even its final fate) depends on mass, so all the astrophysical models about the life of a star are based, in some way, in studying the orbits of double stars. This concept is so important, that I would like to suggest to people really interested in getting the complete picture of the "stellar concept" to complement "Observing and Measuring Visual Double Stars" with another excellent book from the same Springer-Verlag collection titled "Observer’s Guide to Stellar Evolution" by Mike Inglis.

Yet, what the community of double-stars amateur astronomers needs is another book written for those observers not specially interested in measuring doubles, but to simply enjoy the views of these beautiful celestial objects and written at the same high standards of "Observing and Measuring Visual Double Stars". In any case, the book reviewed here is a "must-have". Absolutely recommended.

Luis Argüelles
Oviedo, Spain, 2004
 
 
 
The Alchemy of the Heavens – Searching for Meaning in the Milky Way
Ken Croswell
356 pages
Publisher: Anchor; (February 1, 1996)
ISBN: 0385472145

Minding the Heavens: The Story of Our Discovery of the Milky Way
Leila Blekora
406 pages
Publisher: Institute of Physics Publishing; 1st edition (November 2002)
ISBN: 0750307307

After having kept my nose to the working-world grindstone for nearly 30 years without glancing at the heavens, when my young son asked me if he could have a telescope for Christmas about 5 years ago, I felt a flood of memories rush to my consciousness. These were primarily fond memories of time spent with my older brother, trying to figure out how to operate and see interesting things in the night skies of 1960s suburban Chicago,  with his 70mm Sears refractor on a shaky but usable German mount. I’ve always loved the night, and with my family’s move to the suburbs of New York City in 1999, I could finally indulge my son’s wish to observe with a modern, goto telescope, and recreate with him some of those lost but glorious nights spent with my brother, when I was my son’s age.

Of course, once my boy learned that there are bugs and scary animals out at night (the skunk is my suburban town’s mascot), he decided that he’d rather read about the solar system than observe it first hand. But I was hooked. And eventually I found my way to double stars, whose beauty and variety have held my attention for several years now.

As I observed over the last several years, I found myself naturally drawn to understand more about the objects of my interest. I became especially aware of both the spectacular advances in our understanding of the universe in the last century, as well as the limits of our knowledge. One of the questions that kept occurring to me was, considering our position inside of it, how did we ever figure the shape, size, and elements of our own Milky Way Galaxy? Its not like we could send a satellite out far enough to get the kind of photograph of the Milky Way that we can easily make of, say, our neighbor, the Andromeda Galaxy (we’re just barely breaking out of the Solar System after 40 years in space…). Who put together the information that led to our knowledge of the galaxy, and what techniques and methods did they use to make their discoveries that led us to our knowledge of our own galactic neighborhood?

The answer to my questions and the story of the discovery and the discoverers of the Milky Way are to be found in these two books by Ken Croswell and Leila Belkora. After I received the recommendation for both books from this group, I managed to find both books in paperback on the ABEbooks website.

I read Croswell’s book first. A quote from his introduction lays out the book’s goal:

“ In recent decades, astronomers have delved into the intricacies of the Milky Way and painted a vivid portrait of our Galaxy’s structure, evolution and origin. Indeed, with the plethora of recent discoveries, the Milky Way itself almost seems to be a new galaxy….But until now, no book for the general reader has presented these accomplishments or told the full story of our Galaxy – following the path from ancient times, when some viewed it as a river in the sky, to the present, when astronomers use it as a laboratory for the study of the formation of galaxies and even of the entire universe.”

The grand achievement of the 20th century’s deciphering and understanding of the Milky Way, and through that knowledge, to come to a deeper understanding of the universe and our place in it, is Croswell’s subject. Croswell presents the main observers and theorists of the 20^th century, (Kapteyn, Shapley , Hertzprung, Baade, Hubble, Sandage, Hoyle) and explains their discoveries in terms that a layman can understand. There is a useful, basic glossary of terms, some good diagrams explaining the ideas, some pictures that are very familiar, and a bibliography for further reading. I found this to be an enjoyable read, one that flows very well from chapter to chapter, from the classification of stars to the discovery of the origin of all of the elements within them, from the measurement of metallicity through spectroscopy to the measurement of galactic distance through parallax, to the search for exo-planetary systems and extraterrestrial life. In the end, I felt that Croswell gave a good, complete overview of the topic, with lots of interesting comments and quotes from the scientists involved. Though written in 1995, the book feels very up to date – until you notice that there were only two exo-planetary systems known at that time (just nine years later, we know of over 100 such systems!)

In “Minding the Heavens”, Leila Belkora takes a different tack to the story of the discovery of the Milky Way galaxy and its place as a galaxy among a universe of galaxies by examining the lives of seven of the astronomers who contributed most to our understanding of our home galaxy. The lives and discoveries of Thomas Wright, William Herschel, Wilhelm Struve, William Higgins, Jacobus Kapteyn, Harlow Shapley, and Edwin Hubble form the basis for Belkora’s book. Not as technical as Croswell, her book seemed to me to give more of a flavor of the personalities and times of these great men of observational astronomy than Croswell. Belkora tends to be a bit repetitive, as one might imagine the lives and concerns of these men have quite a bit of overlapping themes. But it was an interesting and informative read nonetheless, and having read Croswell, went much quicker than the first book. And because it was less technical than Croswell’s book, Belkora was somewhat more enjoyable – not exactly a beach book, but easier and more relaxed while covering much of the same material and injecting more of the personalities of the astronomers.

For those of us who want to know more about our own neighborhood of the universe, and to learn about the theories and the personalities that have led us to the knowledge we have today, both “Alchemy of the Heavens” and “Minding the Heavens” are fine reads. I learned a lot from them this summer that already has enhanced my enjoyment of the stars.

Morgan Spangle
New York, 2004