Notes from Under Sky

Orion Takes a Turn for the Better

In which I review this book

Title: Turn Left at Orion, 3rd edition, by Guy Consolmagno and Dan Davis
Price: $24.95 (list)
Published 2000 by Cambridge University Press
ISBN 0-521-78190-6, 224 pp.

There are a few astronomy books which, it seems, are nearly universal recommendations. One of them is Terence Dickinson's Nightwatch, a beautifully produced introduction to astronomy. Dickinson's book covers a lot of ground, none of it in any great depth. In terms of equipment, for example, a better reference source is The Backyard Astronomer's Guide, co-written by Dickinson and Alan Dyer. In terms of observing targets, one of the books mentioned most often is Turn Left at Orion.

Guy Consolmagno works at the Vatican Observatory. He is also the author of Brother Astronomer, which chronicles the oft-misremembered history of the relationship between religion and the science of astronomy. In Turn Left at Orion, he recalls his own introduction to astronomy, and the desire to find objects worthy of observing through a small telescope. Now, especially on the Internet, there is plenty of bravado about what a "small" telescope is. Sometimes, in an attempt to impress others with our astronomical worldliness, we deride 6-inch telescopes as "small." And for some targets, for some observers, perhaps they are. But for most beginners, particularly with the advent of small computerized telescopes, 6 inches is not small. For the benefit of those readers, Consolmagno treats 6-inch telescopes as large, and reserves the term "small scope" for those under 4 inches in aperture.

There aren't a lot of deep sky observing guides for small telescopes. Stephen O'Meara's The Messier Objects comes to mind, and certainly the Messier objects are a good place to start, but O'Meara is an advanced, ambitious observer. Beginners would likely find themselves swamped by O'Meara's meticulous descriptions of details upon details, and lose the wonder of deep sky objects.

In contrast, Consolmagno is a gentle teacher. Many advanced observers will consider the caveats about objects being dim, or difficult to resolve, or hard to find—well, they may find these warnings too conservative. Generally it's implied throughout this book that a 2-inch telescope is only capable of seeing down to about the 11th magnitude; O'Meara suggests the limit is probably about a magnitude deeper than that. But that might be just right for beginners, who come to the hobby looking for awe-inspiring sights and should find them in quantity here.

The main part of the book, on deep sky objects, is divided into five main parts—one for each season in the northern hemisphere, and one last one devoted to southern hemisphere objects. For each object (or set of objects, if they're very close to one another), the authors give the name, the instruments and conditions in which it is best seen, the power (low, medium, or high) you should use to see the object, and a kind of "wow" rating, from one to five telescopes. (Only the Orion Nebula and the Magellanic Clouds get the five-telescope rating.) Objects are mapped three times: a wide field, about 10 or 15 degrees across, to show the object's position in the sky; a finderscope view, a few degrees across; and a telescope view, whose width depends on the recommended eyepiece power.

The wide-field "map," as you might expect, shows north up and east to the left. The finderscope view is inverted, with north down and east to the right. The telescopic view is shown with north up and east to the right, which might seem odd to Newtonian owners, but remember that this book is designed for small-scope owners, and to the authors, that means scopes under 4 inches. Most scopes in that size range come with star diagonals, in which the view is mirror-imaged—hence north up and east to the right. Users of equatorially mounted refractors and small compounds can read the map almost directly; those with alt-az scopes may need to rotate them, but at least a mirror won't be needed. They will be needed by Newtonian users, unless you're good at mentally reflecting images.

Accompanying these maps is excellent text describing the general nature of the objects, how to find them, what to look for once you get them in the field of view, and some incidental information about the objects, such as their distance, or some interesting physical properties. One key feature that is missing from even some more advanced books (such as the Night Sky Observing Guide series by George Keppel and Glen Sanner) is a quick reference list of objects that can be found near the titular object. So, for example, in the entry for M71, we find references to the double stars zeta and theta Sagittae, and Brocchi's Cluster (aka Collinder 399, aka the Coathanger). The book contains, nominally, about 100 objects, but including these references, the number is probably closer to a few hundred, more than enough to keep the beginning skygazer occupied for some time. No coordinates are given along with the object descriptions, but for those interested in such details, they are collected in an appendix at the end of the book.

The third edition includes some updated information—in particular, distances to stars take into account results from the Hipparcos mission, which were released in 1997, after the second edition had already been published. The book also contains a section on observing the planets, and for this edition, the table of positions has been updated. The new edition has also been corrected for errors, although a few unimportant ones remain. In the section on M11, for instance, the text refers to delta Scuti, a star "just east" of eta Scuti, although the map itself correct shows delta southwest of eta. Few if any of these errors will or indeed should worry the novice.

More seriously, the labelling used in the wide-area maps is difficult to read, especially under low light levels. Many star and object names are set in an outline font, an unusual choice that hinders readability. These should simply use a normal, sans-serif font. I also wish that the main text had been set in a text font (a serifed font like Times) rather than Helvetica, a display font normally reserved for titles, but that's perhaps just a personal preference. Strangely, only the text for the DSOs is in Helvetica—elsewhere, it's in Times Roman.

Overall, though, the strengths of Turn Left at Orion far outweigh the few minor weaknesses. I heartily recommend the new edition for beginning observers.

Copyright (c) 2000 Brian Tung