GENERAL ASTRONOMY ARTICLES

THE CONSTELLATIONS Part 1
NAMES and ABBREVIATIONS

I N T R O D U C T I O N

All stars to the naked eye appear only as tiny pinpoints of light in the blackness of the night sky. There are more than 6 500 visible in the whole sky, with roughly half being visible at any one time from the observer’ horizon, though admittedly there are slightly more visible in the southern hemisphere. From the dawn of human history the stars have been broken into groups called constellations. Most are patterned images represent renown gods, heros and heroines, animals or other human-made objects.

All forty-eight constellations originated from classical antiquity but most of the southern ones were added in the 15th Century. Today eighty-eight constellations are now officially recognised and agreed. At one time constellations differed between the various countries throughout the world, which at one time, totaled as many as one-hundred-thirty in common usage. Some of these groups were classified as asterisms - subgroups of the constellations, that are similar to a particular part of an object or part of the constellation’ anatomy. More than one-hundred and twenty-seven are commonly recognised. Ie. The Pleiades, the Hyades or the Square of Pegasus. In the southern hemisphere; The False Cross, Orion’s mid-centre known as The Pot - which in the northern skies is called Venus’s Mirror.

Many of the southern Milky Way constellations were once contained in the original classical mega-constellation of Argo Navis, that at one time covered the entire southern sky below the horizon of the Europeans. Argo Navis was later subdivided into more manageable pieces by Nicolas Louis de Lacaillé, who also named another fourteen southern constellations - thirteen being recognised today. Most of these remain the brightest and the most prominent southern constellations. Later in the 16th Century, both the Dutch navigators Pieter Keyser and Frederick de Houtman named twelve other southern constellations, while in the 17th Century Johann Bayer and Johannes Hevelius divided the rest. Many of these new names of these constellations are now not recognised, many are still in use.

Originally the constellations had no real defined boundaries, except for the interpretive ‘head’ or ‘foot’ of any particular group. It was not until 1925 that the then new International Astronomical Union (I.A.U.) - the governing body for deciding astronomical nomenclature and naming systems - specified an internationally agreed position and subdivision of the constellation boundaries. The initial work on these constellations was commissioned by the I.A.U., who employed the independent French draughtsman, Eugene Delporte (1882-1953). Delporte adopted the northern boundaries originally established by Johann Bode, which were set for the beginning epoch of 1st January 1875. Towards the southern section of the sky, around about the same time, was mainly adopted using recommendation of Benjamin Gould. Delporte’ draft selections were to be only slightly modified, with the final version becoming the constellation boundaries of all constellations that have remained till this day. All the stars, including celestial or deep sky objects contained with in those boundaries became assigned to that constellation.

However, one significant change to these boundaries has been the precession of the equinoxes, which slowly changes the stellar positions through the centuries. This also changes the fixed constellation boundaries which are slowly being twisted askew. Looking at any detailed star chart, the boundaries in some places of the sky no longer properly align north to south, thus changing the positions of the outlines in both right ascensions and declinations. In some cases, including Pavo, Triangulum Australe and the southern boundary of Dorado - that also passes through the Large Magellanic Cloud, these distortions are obvious and acute. In the distant future these boundaries may have to be redefined, thus changing the recognised constellations again.

All eight-eight constellations were selected from the most common groups that were being used at the time. (See Index of the Constellations and Pronunciation of Names.) This official list was first adopted by the IAU in 1922. Some changes were adopted, such as officially divided Argo Navis into its component parts - deemed too large to properly name and number the stars it contained. Argo Navis is now the constellations of Vela, Puppis, Carina and Pyxis.

Other changes were not adopted. Some, for example, wanted to include both the Small and Large Magellanic Clouds as constellations in their own right - to be called Nebecula Major (NMa) and Nebecula Minor (NMi). Changing them to constellations were again formally suggested in 1964 (Trans. IAU. XII B, p.269.) but this was not been commonly adapted - though it would have been if everyone started used it! Few did. An example was the attempted popularising by E.J.Hartung with his 1968 release of “Astronomical Objects for Southern Telescopes” (AOST2). Nevertheless, this recommendation was never formally accepted by the I.A.U, so they had to remain as mere odd-named asterisms especially in the even light that they are really galaxies - small companions to our Milky Way Galaxy.

For the northern constellation from antiquity, only the constellation of Antinous was the only one deleted. Several popular constellations of the time were also removed. A short list of some of these, which sometimes appear in older books is given below. (Table 2)

THE CONSTELLATIONS

The SMALLEST and LARGEST CONSTELLATIONS

NOTES

Argo Navis now includes Carina, Puppis and Vela. Pyxis was once named Malus.
Total Area for Argo Navis is 1867.267 square degrees.
Area of the entire sky is 41 253 square degrees.
Scorpius is the astronomical name for the constellation, while Scorpio is the astrological term.
Nebeculae Major (NMa) culminates on December 13
Nebeculae Minor (NMi) culminates on October 3

Shortened Terms and Older Deleted Names

Reduction of some constellations names was mercifully made.

Those highlighted in RED are Southern Constellations.

NOTE: Nebeculae Magellani are both the LMC & SMC

Last Update : 13th September 2007

Southern Astronomical Delights © (2007)

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