Death Of A Star

The other day, a friend told me that my second-favourite star might be dying. Betelgeuse is already a pensioner as stars go; possibly over nine million years old. Age is a bit meaningless when you’re talking about stars though. The Sun, our nearest star, we think of as present, alive, omnipresent. But light from Betelgeuse takes about 600 years to reach us on Earth, as we prance around our own star, and that means that, if the signs are being read aright, Betelgeuse is already gone. We are just observing its decline 600 years later.

It was Christmas night, on the way back from the midnight service in Dunkeld, that I last saw Betelgeuse. The night was clear and frosty. We pulled off the back-road, switched off the car lights and walked into the icy air. A fox barked in the distance; we were silent, awestruck. The Milky Way strode across the sky, Sirius, the Dog Star, was blue indeed. I began pointing out the names of constellations I knew, and making up the ones I wasn’t sure of, because I can never do enough stargazing for all the names to stick. Betelgeuse is easy, because of its reddish hue and its position as the right shoulder of Orion the Great Hunter. I was a bit nonplussed, because it wasn’t as obvious as usual, but thought no more of it till my friend told me the news.

It’s red because it is something called a Red Supergiant (a sign of ageing in stars). And it’s getting dimmer and dimmer, a state which is said to indicate a loss of mass. With twenty times the mass of the Sun, Betelgeuse has a way to go, but the eventual pattern is an expulsion of dust leading to the star’s explosion as a supernova. If that happens (and it might not, yet, at any rate, because Betelgeuse is a “variable” star, whose brightness goes up and down in cycles), it will create a show of light brighter than the moon, capable of casting shadows on Earth. It might even be visible by day. And then it will be gone.

On many levels, I’d miss Betelgeuse. The physics of supernovae is going on constantly all over the universe, and one day it will happen to our Sun as well. Stars die. But Betelgeuse is a vividly recognisable part of a much-loved constellation I associate with the depths of winter (as well as being the star around which the home planet of Ford Prefect orbits*). Constellations may be unscientific and artificial, but they paint pictures through which we navigate our ignorant way through a universe too fabulous to designate merely with letters, numbers and formulae. Michel Serres, in  The Five Senses, says that if we abandon the naming of stars and constellations “night has lost its giants and animals.”**

What will Orion, the Great Hunter, do without a right shoulder?

“The thing once called a star is classified, distinguished and divided into new families…..designated by a corpus of codes and categories, by a collection of calculations and theories……things simply called stars hardly exist any more.”**

I love the science of the universe, but I also love its art, its language and its inspiration. Much as I’d like to see a supernova, personally I hope Betelgeuse is just being variable and brightens up again the starry nights of winter.

*Adams, Douglas: The Hitchhiker’s Guide to the Galaxy (Heinemann, 1986)
** Serres, Michel: The Five Senses: A Philosophy of Mingled Bodies (in English: Bloomsbury Academic, 1985)