Constellations – 1

Ian Ridpath    (Member, IAU Working Group on Star Names)

THE CONSTELLATION NAMES and three-letter abbreviations in this table are those officially recognized by the International Astronomical Union (IAU), astronomy’s governing body. The original list was agreed in 1922 at the IAU’s first-ever General Assembly – click for a scan of the published list, and a discussion of how the choice of names came about. These names, along with the first official constellation boundaries, were enshrined in two IAU books authored by the Belgian astronomer Eugène Delporte (1882–1955), Délimitation scientifique des constellations and Atlas Céleste, both published in 1930. These books by Delporte remain the definitive references on the naming and delineation of the constellations.

Unfortunately, the IAU itself upset this happy consensus in 1932 when it agreed a second list of names with alternative four-letter abbreviations. In this second list, Corona Australis became ‘Corona Austrina’. In 1955 the IAU repealed these alternative four-letter abbreviations but failed to correct the Corona Australis/Corona Austrina confusion. Corona Austrina continued to appear in the constellation list given by the IAU on its own website until 2008, as did the long-defunct constellation Argo, although the rest of the astronomical community followed the Delporte books. These anomalies have now been rectified – see the IAU’s page on the constellations.

The constellation areas in the table are those calculated by A. E. Levin (Handbook of the British Astronomical Association, 1935; reprinted 1972). I have rounded the areas in square degrees to one decimal place, and the percentages of sky coverage to three decimal places. Levin gave separate areas for Serpens Caput and Serpens Cauda, two halves of the same constellation, but here I have combined them into one.

For details of the history and mythology of each constellation, see my Star Tales pages.

For a discussion on names of individual stars, see my page on Star Names.

Lacerta–Vulpecula »

* NOTES ON COLUMN HEADINGS:

Visibility range (full) gives the range of latitudes from which each constellation rises fully above the horizon at some time. Stars close to the horizon will be considerably dimmed by atmospheric extinction.

Visibility range (partial) gives the latitudes from which the constellation only ever rises partly above the horizon. Constellations which never rise more than a few degrees above the horizon from a given latitude will be effectively unobservable.

Number of stars ≤6.5 gives the number of stars within the constellation of magnitude 6.5 and brighter as listed in the Hipparcos Catalogue.

Origin:

1. Original Greek constellations listed by Ptolemy in the Almagest

2. Considered by the Greeks as part of Leo; made separate by Caspar Vopel in 1536, followed by Gerardus Mercator in 1551.

3. The 12 southern constellations of Pieter Dirkszoon Keyser and Frederick de Houtman

4. Constellations added by Petrus Plancius

5. Seven constellations of Johannes Hevelius

6. The 14 southern constellations of Nicolas Louis de Lacaille

7. Part of the original Greek constellation Argo Navis, dismantled in the 18th century by Nicolas Louis de Lacaille.

Who were Ptolemy, Keyser, de Houtman, Plancius, Hevelius, and Lacaille? For more on the origin and originators of the constellations, see Chapter One of Ian Ridpath’s Star Tales.