Betelgeuse, Betelgeuse, Betelgeuse! Is a Familiar Star About to Explode?

We think of the night sky as reliable and unchanging. The sun sets every evening revealing the same stars found in familiar patterns throughout the year. Those patterns are so predictable, in fact, that we use them to orient ourselves here on Earth. This steadiness is a result of the timescales required for any particular step in the stellar evolution process. It takes millions, even billions, of years for stars to live out their lives. In our lifetimes, we see only a snapshot of their life story. From the star’s perspective, we are but a tiny blip in the timeline. 

When a star changes on timescales we can actually observe, this change is big news. That's why all eyes are on Betelgeuse.

So when a star changes on timescales we can actually observe, this change is big news. And that's why right now, all eyes are on Betelgeuse. I'll tell you more in a moment.

What is Betelgeuse?

Betelgeuse is what is known as a red super giant star. This is what most stars, including our Sun, will eventually become as they near the ends of their lives. Betelgeuse is only 8 million years young, which makes it a relative baby compared to our 4.5 billion-year-old sun. So why is it facing down stellar death?

Stars spend most of their lives fighting back against gravitational collapse by converting mass into energy via nuclear fusion. Bigger, more massive stars have more fuel for this fusion but they also burn through that fuel much faster. Think of a Chevy Silverado with its 36-gallon gas tank compared to a Toyota Prius that holds 12 gallons. The Chevy has more fuel to start off, but you’ll still have to fuel up sooner in the Chevy because it uses that fuel faster. Betelgeuse is over ten times the mass of our sun so it has ten times the fuel to start with, but it also has a luminosity of 140,000 the times of our sun, which means it burns through that fuel 140,000 times faster.

If we were to plunk Betelgeuse down in our solar system in place of our sun, the giant star would swallow Mercury, Venus, Earth, and Mars.

When a star uses up all of its fuel for nuclear fusion, its outer layers begin to expand. The star becomes larger (hence the “giant” in its name). Betelgeuse, in particular, is 1,400 times larger than the sun. If we were to plunk Betelgeuse down in our solar system in place of our sun, the giant star would swallow Mercury, Venus, Earth, and Mars. The outer edges of its surface would even tickle Jupiter in its...

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