Zaphod, call home!

Betelgeuse may have had a slight accident:

The red giant star Betelgeuse in the constellation Orion — famed as the home sun of Hitchhiker's Guide to the Galaxy characters Zaphod Beeblebrox and Ford Prefect — is shrinking rapidly. Astronomers say that it has shrunk by 15 per cent since 1993, by which they mean that it actually did so in the mid 16th century. It may, in fact, already have exploded.

Betelgeuse, before it shrank, was thought by astro boffins to be so large that if it were placed in the middle of our solar system, Jupiter — out beyond the asteroid belt in reality — would lie inside it. Now it has shrunk by a distance equal to the orbital radius of Venus.

"To see this change is very striking," said Charles Townes, UC Berkeley emeritus physics prof and Nobel Prize winner. "We will be watching it carefully over the next few years to see if it will keep contracting or will go back up in size."

Fascinating, right? But wait — it gets even more interesting, in the Chinese sense:

The huge star, one of the brightest in the sky, is thought to lie about 430 light years from our solar system, so the changes being observed now actually occurred in 1579 AD. Many boffins believe that Betelgeuse is so vast that it's liable to go supernova — that is, blow up with stupendous, galaxy-shaking force — within a millennium or so. Indeed, it might already have exploded at some point in the last 430 years, in which case the flash wouldn't yet have reached us.

If Betelgeuse has gone supernova in the last 400-odd years, the impact could be rather impressive. The good news is, as far as we can tell, we're outside the kill zone of Betelgeuse. We think.