Betelgeuse, a star so large its shape can be seen through the Hubble Space Telescope.
Betelgeuse's position in the constellation Orion.
The nearby, well-known and very bright star may soon explode in a supernova, according to data released by U.C. Berkeley researchers Tuesday.
The red giant Betelgeuse, once so large it would reach out to Jupiter's orbit if placed in our own solar system, has shrunk by 15 percent over the past decade in a half, although it's just as bright as it's ever been.
"To see this change is very striking," said retired Berkeley physics professor Charles Townes, who won the 1964 Nobel Prize for inventing the laser. "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."
Betelgeuse, whose name derives from Arabic, is easily visible in the constellation Orion. It gave Michael Keaton's character his name in the movie "Beetlejuice" and was the home system of Galactic President Zaphod Beeblebrox in "The Hitchhiker's Guide to the Galaxy."
Red giant stars are thought to have short, complicated and violent lifespans. Lasting at most a few million years, they quickly burn out their hydrogen fuel and then switch to helium, carbon and other elements in a series of partial collapses, refuelings and restarts.
Betelgeuse, which is thought to be reaching the end of its lifespan, may be experiencing one of those collapses as it switches from one element to another as nuclear-fusion fuel.
"We do not know why the star is shrinking," said Townes' Berkeley colleague Edward Wishnow. "Considering all that we know about galaxies and the distant universe, there are still lots of things we don't know about stars, including what happens as red giants near the ends of their lives."
Eventually, the huge star may become a nesting doll of elements, with a mixed iron-nickel core surrounded by onion-like layers of silicon, oxygen, neon, carbon, helium and hydrogen.
As the iron fuel runs out, it may explode into a supernova, blasting newly created elements out into the universe and leaving behind a small, incredibly dense neutron star.
All the heavier elements in the universe — including all the oxygen, carbon and iron in your own body — were created in such a way.
It's possible we're observing the beginning of Betelgeuse's final collapse now.
If so, the star, which is 600 light-years away, will already have exploded — and we'll soon be in for a spectacular, and perfectly safe, interstellar fireworks show.