Cœlum Australe Stelliferum
French astronomer who catalogued southern stars and named 14 constellations.
Nicolas Louis de Lacaille . · Public domain
Abbé Nicolas-Louis de Lacaille was a French astronomer and geodesist who named 14 out of the 88 constellations. From 1750 to 1754, he studied the sky at the Cape of Good Hope in present-day South Africa, observing over 10,000 stars using a refracting telescope. His southern star catalogue, published posthumously in 1763, introduced 14 new constellations that have since become standard.
- born
- 15 March 1713
- died
- 21 March 1762
- field
- Astronomy, geodesy
- nationality
- French
- known_for
- Naming 14 constellations; southern star catalogue Coelum Australe Stelliferum; arc measurement at the Cape of Good Hope
Lore & Background
Lacaille was born at Rumigny in the Ardennes in eastern France and attended school in Mantes-sur-Seine. He studied rhetoric and philosophy at the Collège de Lisieux and then theology at the Collège de Navarre. Left destitute in 1731 by his father's death, he was supported by the Duc de Bourbon. He took deacon's orders, becoming an Abbé, and concentrated on science. Through the patronage of Jacques Cassini, he obtained employment surveying the coast from Nantes to Bayonne and later remeasuring the French meridian arc, a success that earned him admission to the Royal Academy of Sciences and a professorship at the Mazarin college.
His desire to determine planetary distances trigonometrically led him to propose an expedition to the Cape of Good Hope in 1750. There, with the support of Dutch Governor Ryk Tulbagh, he constructed an observatory on the shore of Table Bay. Over two years he observed nearly 10,000 southern stars, requiring nightly observations for over a year, and noted 42 nebulous objects. He also determined solar parallax using Mars as an intermediary, with near-simultaneous observations from Europe carried out by Jérôme Lalande; lunar parallax was determined separately. His southern catalogue, Coelum Australe Stelliferum, was published posthumously in 1763, introducing 14 new constellations, including Mons Mensae, the only constellation named after a terrestrial feature (Table Mountain).
Reader's Guide
Lacaille's Coelum Australe Stelliferum represents a foundational contribution to southern hemisphere astronomy. By systematically cataloguing nearly 10,000 stars and introducing 14 constellations—such as Antlia, Fornax, and Telescopium—he filled a significant gap in celestial mapping. His work at the Cape of Good Hope also included an arc measurement to determine the Earth's radius in the southern hemisphere, though his result suggested a prolate Earth. Later, George Everest and Thomas Maclear showed that his latitude observations were affected by gravitational deflection from nearby mountains, and Maclear's subsequent measurements corrected the error. Lacaille's catalogue, despite errors noted in an 1890 study by B. A. Gould, remains a landmark. His broader legacy includes lunar tables for longitude determination, a standard catalogue of 398 bright stars, and his role as a teacher of Antoine Lavoisier and Jean Sylvain Bailly. The crater 'La Caille' on the Moon and asteroid 9135 Lacaille are named after him.
Did You Know?
- Lacaille named 14 out of the 88 constellations, including Mensa, the only constellation named after a terrestrial feature (Table Mountain).
- His southern catalogue, Coelum Australe Stelliferum, was published posthumously in 1763.
- An 1890 study by B. A. Gould found a considerable number of errors in Lacaille's catalogue.
- Lacaille's arc measurement at the Cape suggested the Earth was prolate, but later work by Thomas Maclear confirmed the deflection of the vertical caused by nearby mountains.
Gallery
Frequently Asked Questions
Who is behind Cœlum Australe Stelliferum?
The catalogue was compiled by the French astronomer and geodesist Abbé Nicolas-Louis de Lacaille, who carried out his fieldwork from the Cape of Good Hope between 1750 and 1754. Working with a refracting telescope, he charted more than ten thousand stars in the southern sky.
What does Cœlum Australe Stelliferum actually contain?
It is a systematic star catalogue of the southern celestial hemisphere, recording positions and magnitudes of stars that European observers had previously left largely uncharted. The work also formally introduced fourteen brand-new constellations to the official sky map.
When was Cœlum Australe Stelliferum published?
Lacaille finished his observations during his Cape of Good Hope stay in the early 1750s, but the catalogue did not appear in print until 1763, one year after his death on 21 March 1762. It is therefore remembered as a posthumous publication.
Why is Cœlum Australe Stelliferum considered important?
It closed a major gap in European astronomy by providing the first thorough, systematic mapping of the southern sky from a low-latitude vantage point. The fourteen constellations it introduced—such as Carina, Pictor, and Horologium—still sit among the 88 officially recognised constellations today.
How does Cœlum Australe Stelliferum's story end?
Lacaille died on 21 March 1762, barely a year before the finished catalogue was finally released in 1763, so he never saw his life's work in print. Nevertheless, his observations and the naming of those fourteen southern constellations became a permanent part of the modern night sky.
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