Rigel

Rigel is a blue supergiant of spectral type B8Ia located about 860 light-years from Earth in Orion. Despite its Beta designation, it is usually the brightest star in Orion at magnitude 0.12 (Betelgeuse is variable and occasionally rivals it). Rigel is extraordinarily luminous — roughly 120,000 times the luminosity of the Sun — making it one of the most luminous stars visible to the naked eye. It is about 21 times the mass of the Sun and 79 times its diameter. Rigel has a faint companion, Rigel B, a magnitude 6.7 star that is itself a close binary.

Rigel marks the southwestern foot of Orion and is unmistakable as a brilliant blue-white star. The companion Rigel B at magnitude 6.7 lies about 9 arcseconds away but is overwhelmed by the primary's glare; a 150mm telescope at high power under steady seeing can split it. The contrast between Rigel's blue-white color and Betelgeuse's red-orange in the same constellation is one of the finest color contrasts in the sky. Best observed from November through March.

The name Rigel comes from the Arabic 'Rijl Jauzah al Yusra' meaning 'the left foot of the central one.' It has been a prominent navigation star throughout history. Rigel B was first discovered by Friedrich Georg Wilhelm Struve in 1831. As a massive supergiant, Rigel is expected to end its life as a supernova within the next few million years.