Betelgeuse, also designated α Orionis, is on average the ninth-brightest star in the night sky and second-brightest in the constellation of Orion. It is distinctly reddish, and is a semiregular variable star whose apparent magnitude varies between 0.0 and 1.3, the widest range of any first-magnitude star.

Distance to Earth: 642.5 light years

Surface temperature: 3,500 K

Mass: 1.531 × 10^31 kg (7.7 M☉)

Radius: 617.1 million km (887 R☉)

Surface gravity (log g): −0.5 cgs

Did you know: Betelgeuse is Alpha Orionis, despite the fact that it's fainter than Orion's other bright star, Rigel.