Marine Glossary

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star names

For navigational purposes, stars have two naming conventions: proper names such as Canopus or a Greek letter designation called the Bayer system such as Alpha Carinae, meaning the alpha star of the constellation Carina. The alpha star means most dominate, or if all are about the same brightness, the first one in a logical sequence of numbering, as in the Big Dipper, which goes alphabetically from Alpha Ursa Majoris (Dubhe) at tip of the cup to Eta Ursa Majoris (Alkaid) at the end of the handle. Officially the constellation name in this system is in the latin genitive form (belonging to), but Alpha Ursa Major would be adequate for record keeping and communications. All magnitude-1 stars (see brightness and magnitude) and most magnitude-2 stars have proper names. Less bright stars typically do not.

The 57 stars listed on the daily pages are called navigational stars. They are also on the Index to Selected Stars in the back of the Almanac (p. xxxiii), listed both alphabetically and by their unique permanent number. These are bright stars, magnitude 1 or 2, but they are not chosen by brightness alone, but rather selected uniformly around the sky so that several of them will be in view at all times from any location. Polaris is notably not on that list, though it is used routinely for navigation.

There are another 116 stars listed in the back of the Almanac that do not show up on the daily pages. That full list (174 stars) includes the navigational stars, and is presented in a unique manner. The first half of the year (January to June) lists the stars by their Bayer designation, whereas from July to December they are listed by their proper names. This can be an important nuance to know when it comes to some star ID questions. All navigational stars have a proper name. For more info see the classic Victorian text: Star Names Their Lore and Meaning by Richard Hinckley Allen, which is online.

The star list in the back of the Almanac is sorted according to SHA. If you know the star but not its SHA, check the star maps in the Almanac or the map we have on our cel nav text support page.