IAU-Accepted Star and Constellation Names

Babylonia

To understand the development of the Greco-Roman and Arabic star cultures, we need to go further back to ancient Mesopotamia, ruled at one point by the Babylonian Empire. Many of the Greek constellations as well as some of the indigenous Arab constellations of antiquity derive from Babylonian associations, such as the signs of the Scorpion and the Spike of Wheat.

The most widely circulated Bablyonian source on astronomy was 𒀯𒀳 ^mulAPIN, named for the first constellation it describes. It is a compendium of star and constellation names, rising and setting times for various stellar figures (elucidating their positions), knowledge on how to predict the movement of the sun, planets, and moon, and information on how to regulate the calendar. From this we can infer the origins of many modern constellations, especially those of the Zodiac. Information on the specific transfer of the constellations from the Babylonian system to the Greco-Roman system can be found on the modern constellation pages. In summary, some such as Scorpius, Sagittarius, and Cancer were quite direct transfers, while some such as Andromeda, Pisces, and Virgo had more complex transfers involving the morphing of the figure throughout time. There is also the case of Libra, which evaded Greek adoption but was later adopted by the Romans.

Ancient and Classical Greece

Eudoxus and Aratus, Phaenomena

Lying at the foundation of Greek star culture are the works of Eudoxus: Phaenomena, 'appearances', and Enoptron, 'mirror'. While neither work survives in the modern day, the former was preserved in a poem of the same name by Aratus of Cilicia written for King Antigonus II Gonatas of Macedonia. Aratus's Phaenomena is thus the earliest work detailing the Greek constellations as well as some star names. Both authors were of the fourth century BC, with Aratus coming after Eudoxus.

Aratus identified 48 constellations, but included amongst them the Pleiades and Hydor, 'water', (a region populated by dim stars between Cetus and Aquarius). From this work we also get the oldest Greek star names still in use: Arcturus, Aix (Capella), Sirius, Procyon (which in and of itself was a constellation), Stachys (Spica), Protrygeter (Vindemiatrix), and Propus. These stars were noteworthy as they were calendar stars for the Greeks; that is, they marked important dates. For example, Protrygeter marked the year's first vintage in mid-summer, while Sirius and Procyon marked the beginning of the summer.

While is unlikely that the constellations were truly invented by Eudoxus, there are some clues as to where and when the constellations of Phaenomena were invented based on its writings. Aratus described no constellations of the south, as it was permanently below the horizon to him. However, the region of exclusion for his constellations was not centered on the South Pole of his time, but rather for that of an observer around 35-36°N in latitude during the second millenium BC, corresponding quite well with Mesopotamia during the Babylonian period, providing additional evidence for the transfer of the constellations from the Babylonians to the Greeks besides the similarity of their figures. Thus, it is commonly accepted that the Babylonians and Sumerians were the true inventors of the first modern constellations.

Mythologers

While Aratus briefly touched on the mythology of the constellations, it was the works of various Greek and Roman mythologers that inform us of the detailed tales describing them. The most important of these works are Catasterismi by Ps-Eratosthenes and Astronomica by Hyginus. Other authors such as Manilius, Germanicus Caesar, Apollodorus, and Apollonius Rhodius provide us with more detail on the stories plastered on the night sky.

Ptolemy of Alexandria, Almagest

Ptolemy of Alexandria was a Greek writer of the second century AD who published Almagest, 'greatest', a truly great work containing what was to him the sum total of Greek astronomical knowledge. Within it he catalogued over a thousand stars and described 48 constellations, though Ptolemy's 48 differed from Aratus's in that the Pleiades and Hydor were no longer separate constellations and Stephanos Notios (Corona Australis) and Hippou Protome (Equuleus) were added.

We have naught but five star names attributed to Ptolemy: Aetos (Altair), Antares, Canopus (though it was too far south for him to observe), Basiliskos (Regulus), and Lyra (Vega). However, it is not star names Almagest is remembered for, but rather for the 48 constellations it describes. Ptolemy's work standardised the depictions of the constellations in the night sky with his descriptions of the positions of the stars relative to each other. By various translations, the names of the constellations came to be used by Arabic and European astronomers for the next two millenia all the way to the current date.

Arabia

al-Ṣūfī's Kitāb al-Kawākib al-Thābita and the Golden Age of Islam

Whilst Greek and Roman astronomical writing ceased, Islamic sources began to flourish. The most important Muslim astronomical work was al-Ṣūfī's Kitāb al-Kawākib al-Ṯābita, a tenth century AD translation of Ptolemy's Almagest also containing indigenous Arabic star names, stellar magnitudes as measured by al-Ṣūfī, and two illustrations of each constellation, one as it appeared in the night sky, the other mirrored right-left as it would appear on a globe.

It was with the Arabic authors that the translations of Ptolemy's descriptions of stellar positions within the constellations became names for the stars they described. They also blended these names with those already used by their ancestors in the deserts of the Arabian heartland, such as al-Dabarān (Aldebaran) and al-Nasr al-Wāqiʽ (Vega).

The Muslim Invasions of Europe and the Reintroduction of the Greek System

It was the Muslim incursions and subsequent settlement in regions like Iberia and Sicily that brought Greek knowledge of the constellations back to Europe. Scholars from all across the continent flocked to centres of learning such as Toledo and Córdoba to read and translate Arabic scientific works. It was through this cultural exchange that Ptolemy's works made it back into the European intellectual sphere, translated into Latin. Thus, we have a convulted system of Babylonian and Greek constellations with Latin names containing stars named mostly in Arabic with a smattering of Latin and Greek names.

Renaissance and Early Modern European Astronomy

The Sunderring of Aquila and Leo

Caspar Vopel was the first to introduce new constellations to Ptolemy's system, separating the figures of Antinous and Coma Berenices into their own constellations. Ptolemy had mentioned the figures in Almagest, but instead as parts of Aquila and Leo, respectively. The edits to Ptolemy's system were included in Gerardus Mercator's celestial globe (1551), cementing their presence, though Antinous eventually came into disuse.

The Dutch Mapping of the Southern Sky

Theologian and astronomer Petrus Plancius instructed navigator Pieter Dirkszoon Keyser to fill the constellation-free zone in the southern sky in exchange equipping his voyage with star charts for navigation. It was apparently at Madagascar where Keyser would make most of his observations, as the fleet was docked there for months. While Keyser would die in 1596 in Bantam (modern day Banten, Indonesia), his data on 136 stars made its way back to Plancius who alongside his colleague Jodocus Hondius published them as well as 12 new southern constellations on a globe in 1598. These constellations were Apus, Dorado, Hydrus, Musca Australis (Musca), Phoenix, Tucana, Chamaeleon, Grus, Indus, Pavo, Triangulum Australe, and Volans, all commorating interesting life forms of the fleet's voyage (with the exception of Triangulum Australe). While it is not known whether Keyser himself invented the constellations as his original manuscript does not survive, it was likely rival astronomer and fleetmate Frederick de Houtman that took his data after his death and expanded them, and so he might have had a hand in creating the modern southern constellations instead. Following his second voyage to the southern seas, de Houtman expanded the data set of Keyser to 303 stars and published them and the 12 new constellations in his catalogue as an appendix to his dictionary and grammar of the Malay and Malagasy languages.

Plancius invented his own constellations of the north, such as Columba, Camelopardalis, Monoceros, Jordanus, Tigris, Musca Borealis, and Gallus. The latter four did not survive, however, also resulting in the shortening of Musca Australis to just Musca.

Hevelius and Lacaille

While both the northern and southern skies contained a plethora of constellations, there were still many "unformed regions" of both skies from which constellations could be made. Plancius had already begun the process of filling in the gaps with his aforementioned northern additions, and other astronomers would follow in his footsteps.

One of the first of these constellation inventors whose inventions stuck after Plancius's would be the Polish Johannes Hevelius, who introduced ten constellations in his catalogue of 1687 and posthumously published atlas Firmamentum Sobiescianum (1690). These ten constellations were Canes Venatici, Cerberus, Lacerta sive Stellio, Leo Minor, Lynx sive Tigris, Mons Maenalus, Scutum Sobiescianum, Sextans Uraniae, Triangulum Minus, and Vulpecula cum Ansere. The constellations Cerberus, Mons Maenalus, and Triangulum Minus did not survive, while with the exception of Canes Venatici his other constellations were later shortened to single-name designations.

The next to introduce a set of constellations still in use in the modern day was the French Nicolas Louis de Lacaille, who from his observatory at the Cape of Good Hope under the Table Mountain observed the positions of over 10,000 stars and created seventeen new constellations, mostly named after scientific instruments of his time with the exceptions of Mensa, named for the Table Mountain, and Carina, Puppis, and Vela, the broken-up components of the former Argo Navis. de Lacaille's other constellations are today called Antlia, Caelum, Circinus, Fornax, Horologium, Microscopium, Norma, Octans, Pictor, Pyxis, Reticulum, Sculptor, and Telescopium.

The Modern 88

To varying degrees of success, many other constellations were made out of the night sky by various astronomers, such as Johann Bode who published Uranographia (1801), an atlas containing over a hundred constellations. The problem of constellation bloat might have become even more prevalent had not the new force of the IAU come along, poised to standardise how the heavens would be described going forward. In its first general assembly in 1922, the modern 88 constellations were decided upon, with their borders later drawn by Belgian Eugène Joseph Delporte following lines of constant declination and right ascension. Since then, constellations have been defined not as collections of stars but rather as distinct regions on the surface of the great celestial sphere and have remained quite static.