The second brightest star in the night sky at an apparent magnitude of -0.62, over half a point fainter than Sirius due to that star's close proximity to Earth, Canopus is a yellow supergiant star with a diameter 65 times greater than the sun, and 14,000 times more luminous. It is a Southern Hemisphere star, though it can be seen low in the sky from as far north as the southern states of the US. It is found in the constellation of Carina, the Keel, which is itself a sub-constellation of the gigantic Argo, the ship of the argonauts in Greek mythology.
Canopus is 313 light years away from Earth, a figure established by the Hipparcos satellite, with both higher and lower estimates having been made before then. The difficulty in measurement arises from the fact that stars like Canopus are unusual, and not very well understood. Its official classification is F0II bright giant. It is an extremely large and bright star whose life cycle is uncertain - it may be in the process of becoming a red supergiant, or even contracting from a red supergiant into a denser, hotter star. For the same reason, it is very difficult to guess its age, or when it will die, but it is likely to end its life as a supernova due to its mass.
The derivation of its name is slightly uncertain. Canopus was the pilot of the ship of king Menelaus of Sparta, and his name comes from the Egyptian or Coptic phrase Kahi Nub or Golden Earth. The ancient city of Canopus, east of Alexandria, was also named after him. However, Canopus may also have been the steersman of the Argonauts, and this would fit with its important position in the constellation of Argo.
Canopus has always been extremely important as a navigational landmark due to its brightness, and was known to ancient nomadic cultures as "The ship of the desert". To this day, NASA uses Canopus to orient its spacecraft, using a 'Canopus Star Tracker' in conjunction with its 'Sun Tracker'. Posidonius of Alexandria used it to measure a degree on the surface of the Earth. In ancient Egypt it was a symbol of Osiris. It was also important in African myths and legends - each year it would rise in the South, and in some cultures it was supposed to bring luck to the first person to see it. In South Africa it was known as the ants' egg star, because it appeared in the season when the ants laid their eggs.