Is Betelgeuse getting ready to say goodbye?

In the night sky, there are stars... and then there's Betelgeuse.

Located on the left shoulder of the constellation Orion, Betelgeuse (pronounced "beetle juice") is one of the largest known stars. And despite being over 600 light years (more than 5 quadrillion kilometres) away from our solar system, it is also one the brightest objects in the night sky. Except...

Lately, astronomers have noticed that the mighty star has been dimming. While still a Top 20 star in terms of brightness, 2019 saw it become less luminous. And this led to some speculation. Namely, What if Betelgeuse is about to go supernova — explode and die?

It's a wild thing to think about and it brings up all sorts of questions, some about Betelgeuse, others about stars in general.

What is Betelgeuse?

An artist's impression of Betelgeuse, along with a chart of how it would, or wouldn't, fit in our own solar system. (ESO/L. Calçada)

It is a red supergiant, the second largest class of stars (behind only hypergiants).

Will it explode?

Yes, at some point. Stars the size of Betelgeuse are prime candidates for a supernova.

Which is...?

All stars produce heat and light by burning through tons of fuel. When that fuel runs out, stars dim, collapse in on themselves, then explode outward in a mind-boggling release of energy.

A comparison between telescope images of Betelgeuse taken on January 2019 and December 2019. (ESO/M. Montargès et al.)

How do scientists know it is near supernova?

While they don't know for certain, astronomers have seen that Betelgeuse has both dimmed and shrunk in size over the past year or so. This is what a supergiant would do in the moment before supernova as its fuel runs out.

Okay, is it supposed to explode now?

Perhaps. It is definitely close. Smaller stars, like our Sun, burn through their fuel relatively slowly, living for over 10 billion years or more (the Sun is 5 billion years and is just barely entering middle age). But enormous giants like Betelgeuse burn huge and fast and die young...er. While it is only 8 million years old, it is deep into old age (when it was born, the dinosaurs had been extinct for almost 60 million years).

So Betelgeuse's time is definitely near.

You mean it's time to run outside and watch it right now?!

From the universe's perspective, this will happen any moment. But for us humans? It could be anywhere from this week to 100,000 years from now. Soooo... maybe put the popcorn down. And some recent reports suggest that the star is actually getting brighter again!

The supernova is coming. We just may not get to see it.

But what if we did see it?

Oooo... yes. That's the big question. It would be spectacular! Even though it is so far away, the explosion would burn as brightly as a full moon. Maybe even brighter! Which leaves us torn...

We love Betelgeuse where it is, holding down the fort in one of the most well-known constellations in our sky. But at the same time... that supernova would be something to see, right?

To tide you over, you can watch a simulation of Betelgeuse's supernova in the video below.