This is one of the three parts into which the ancient Greek constellation of Argo Navis, the ship of the Argonauts, was divided by the French astronomer Nicolas Louis de Lacaille in his first catalogue of the southern stars, published in 1756. In that catalogue he gave it the French name Corps du Navire. (His final catalogue, Coelum australe stelliferum, appeared in 1763 containing the same subdivisions but with Latin names.) The other two parts are Puppis, the poop or stern, and Vela, the sails.
Although usually described as the keel, Carina represents the main body or hull of the ship. It contains the second-brightest star in the entire sky, Canopus, a creamy white giant just over 300 light years away, which marks the blade of one of the ship’s two steering oars.
Canopus is not mentioned by Aratus, because the star was below the horizon from Greece in his day. The name first appears with Eratosthenes who was based farther south, at Alexandria in northern Egypt. From there he could see it low in the south, as could Ptolemy, who worked at Alexandria four centuries later. It was the most southerly star that Ptolemy catalogued in his Almagest, and by some way: the next most southerly was the present-day Tau Puppis, over 3° to the north. Eratosthenes and Ptolemy both spelt the star’s name Κάνωβος (Kanobos); Canopus is the Latinized version.
Greek writers such as Strabo and Conon tell us that Canopus is named after the helmsman of the Greek King Menelaus. On Menelaus’s return from Troy with Helen his fleet was driven off-course by a storm and landed in Egypt. There Canopus died of a snake bite; Helen killed the snake, and she and Menelaus buried Canopus with full honours. On that site grew the city of Canopus (the modern Abu Qir) at the mouth of the Nile. Fittingly, modern space probes now use Canopus as a navigation star. Eratosthenes also knew this star by the name Perigee (Περίγειος, i.e. Perigeios, in Greek), in reference to the fact that it remained close to the horizon; this name appeared in Eratosthenes’s entry on Eridanus, not Argo.
The constellation contains a unique star, Eta Carinae, that flared up to become brighter than Canopus in 1843, but has since faded to the limit of naked-eye visibility. Astronomers think that it is a young, massive star that will one day explode as a supernova.
The second-magnitude stars Epsilon and Iota Carinae, along with Delta and Kappa Velorum to the north in Vela, form a cruciform shape known as the False Cross, sometimes mistaken for the true Southern Cross.
In ancient China, Canopus was known as Laoren, ‘old man’, or sometimes Nanji Laoren, ‘old man of the south pole’. He was equated with Shouxing, the god of longevity.
Carina also once contained part of a large Chinese constellation called Qifu, a storehouse for musical instruments, the rest of which was in Centaurus and Vela. However, as the effect of precession gradually carried Qifu below the southern horizon the constellation was repositioned to the north on later star maps, farther into Centaurus and entirely out of Carina.
© Ian Ridpath. All rights reserved