Betelgeuse is the armpit of Orion, literally. That is to say that it’s name translates to just that, and it is located in what astronomers politely refer to today as Orion’s shoulder.
Already the second brightest star in Orion (after Rigel) and the ninth brightest star we can see, it may soon (any day, in fact) become the brightest star in our night sky. That’s because Betelgeuse (or Alpha Orionis) is about to go supernova.
Actually, Betelgeuse is already producing the most light of the visible stars, but does so in wavelengths invisible to our eyes. That’s all gonna change soon, as this red supergiant nears the end of its life as a semi-regular variable star to become a neutron star. This may, in fact, already be happening, but since Betelgeuse is 180 light years away that information will take nearly two centuries to reach us.
We’re pretty sure it has run out of hydrogen fuel and has been fusing heavier elements from helium for a while now, so it’s not a young star. Neither is it a small star. If it were to replace our Sun, the inner planets and the asteroid belt would be engulfed inside it.
The show that it will put on when it goes supernova, will make it brighter than any other celestial object we can see at night — even the moon.
(artist rendering courtesy ESO)