What's That Star Called

Now that daylight savings time is officially done, you may find yourself getting up before the Sun. Looking to the southeast in the morning twilight, you can see a scattering of bright stars. These are the stars of the “Winter Oval”, centred on Orion the Hunter.

The constellation Orion. Betelgeuse is the bright, red star in the left shoulder of the great hunter.

Orion is one of the most recognized star groups in the sky, if not the most. It’s location near the celestial equator, which is basically the Earth’s equator extended into the sky, means that Orion and his nearby pals are visible from just about every inhabited spot on the planet.

This constellation is often seen as a large person from northern latitudes, with a three-starred belt, two knees below, and two shoulders above topped with a dimmer head. It actually looks like what it’s supposed to!

The uppermost shoulder, the bright star above the belt and towards the south, is Betelgeuse (often pronounced ‘beetle-juice’). As with many stars, its name is a slightly off-kilter version of the Arabic name for the star, recorded through torturous medieval translations as anything from bat al-Jauza to ibt al-jauza to bedelgeuze meaning the shoulder or armpit or even hand of a giant. For a neat summary of the somewhat twisted origins of Betelgeuse, read this article by Laurel Brown in the NY Examiner: 

Betelgeuse is interesting for more than its name. It is one of the largest stars (in diameter) visible to the unaided eye. Put Betelgeuse where the Sun is and Jupiter (and Mercury, Venus, Earth and Mars) would orbit inside it. There are bigger stars, but the stellar surfaces of really huge stars are so far from their central fuel sources, they are too cool to emit visible light and blaze away instead in invisible infrared.

Particularly in photographs, but also to the unaided eye, Betelgeuse looks quite red. That’s also because of its size. Betelgeuse is a red giant star, swollen up away from its central fuel source and cooled off until the surface appears a cooler red rather than a bright-hot blue.