Canopus (/kəˈnoʊpəs/)is the brightest
star in the southern constellation of
Carina and the second-brightest
star in the night sky. It is also designated α Carinae, which is Latinised to
Alpha Carinae. With a visual apparent magnitude of −0.74, it is outshone only by Sirius. Located around 310 light-years from the Sun, Canopus is a bright giant of spectral type A9, so it is essentially white when seen with the naked eye. It has a luminosity over
10,000 times the luminosity of the Sun, is eight times as massive, and has expanded to 71 times the Sun's radius. Its enlarged photosphere has an effective temperature of around 7,400 K. Canopus is undergoing
core helium burning and is currently in the so-called
blue loop phase of its evolution, having already passed through the red-giant branch after exhausting the hydrogen in its
core. Canopus is a source of
X-rays, which are likely being emitted from its
corona.
The prominent appearance of Canopus means it has been the subject of mythological lore among many ancient peoples. Its proper name is generally considered to originate from the mythological Canopus, who was a navigator for Menelaus, king of Sparta. The acronychal rising marked the date of the Ptolemaia festival in Egypt. In ancient
India, it was named Agastya after the revered Vedic sage. For Chinese astronomers, it was known as the Old Man of the South Pole.