Posted by: Kash Farooq | January 31, 2011

No, Betelgeuse will not explode and kill us all in 2012

A star called Betelgeuse is about to explode.

[I’ve decided to start pronouncing it Beetle-juice, and not Bet-el-gers. If it’s good enough for The Bad Astronomer, it is good enough for me].

This imminent explosion has been added to the reasons why the Earth will be destroyed in 2012. If solar neutrinos aren’t going to melt the Earth’s core (wow – that was a bad movie), or if Planet X isn’t about to crash into us, then it will be the death rays from a Betelgeuse explosion that will get us.

I can confirm that Betelgeuse is definitely about to explode. About to explode on an astronomical time scale, that is. Perhaps tomorrow. Perhaps next year. Perhaps in a million years. Basically, we don’t know and cannot predict it. And I’m pretty sure the Mayans didn’t predict it either.

From the northern hemisphere we can see Betelgeuse in the winter sky – it is in the constellation of Orion. Find the three stars that make up Orion’s belt, then look perpendicular to this line towards the left. You’ll see Betelgeuse as a bright red star.

Orion

Orion. Betelgeuse is the red star at the top-left of this image.

It is huge star classed as a red supergiant. And when I say huge I mean flippin’ massive. It is at least 1000 times bigger than the Sun. If you moved Betelgeuse to the centre of the Solar System so that it was positioned where the Sun is, it would engulf all the planets all the way to Jupiter.

That’s big.

It is so big that it has actually been imaged by Hubble; it was the first star other than the Sun to ever be directly imaged:

Hubble image of Betelgeuse

This is the first direct image of a star other than the Sun. Called Alpha Orionis, or Betelgeuse, the star is a red supergiant.

Even features such as sunspots have also been imaged:

Betelgeuse sunspots

Betelgeuse sunspots. (Credit: Copyright 2010 Haubois / Perrin, LESIA, Observatoire de Paris)

So, what is happening to it?

The Sun is an average star plodding along at an average rate. However, Betelgeuse started massive and rapidly went through the stellar life cycle stages. The Sun is about half way through its life and is 4 and a half billion years old. Astronomers think Betelgeuse is only about 10 million years old.

Despite this relatively young age, Betelgeuse is essentially an elderly star. When stars get old the reactions in their cores change, producing more and more energy and they start to expand – the radius of such a star grows massively. This will happen to the Sun one day – however, due to its smaller starting mass, the Sun will only turn into a red giant. Betelgeuse started with a much higher initial mass and it has become a super red giant.

Now on to the exploding bit…

Betelgeuse is expected to explode as a Type II Supernova. Such a supernova happens when a massive star runs out of fuel and there is no longer any outward radiation pressure being generated to hold off the effects of gravity. The star collapses catastrophically in on itself (we’re talking over the space of a few hours here), getting denser and denser. Eventually the collapse comes to a screeching halt when the star cannot get any denser. There is a rebound and all the in falling material is suddenly thrown outwards. The star explodes releasing huge amounts of energy.

So, how will this affect Planet Earth?

It won’t. It’s too far away. A star has to be within 25 light years of Earth for it to affect us. And it would have to be even closer to actually harm us.

And one last thing to debunk.

Star Wars, Tatooine, Binary Star sunset

Star Wars, Tatooine, Binary Star sunset

When it does explode, I’m sorry to inform you that it will not appear like the twin suns we see on Luke Skywalker’s home planet of Tatooine. This is what some newspapers are reporting.

We would see it as a very bright object in the sky. Perhaps the same brightness as the Moon. Perhaps bright enough so that we will be able to see it during the day for a few weeks. But, no, it won’t be appear like another Sun. We can’t all pretend we live in the Star Wars universe.

I hope it does explode in my lifetime. That would be cool.

Let’s just hope it doesn’t explode next year. We’ll never hear the end of it.


The above post was recorded for episode 69 of The Pod Delusion. The Pod Delusion is a podcast about interesting things.


Responses

  1. One thing I love more than an astronomy blog is an astronomy blog that debunks bad astronomy! Good work.

  2. […] worry too much just yet though, it’s not due to blow this year, but it could very well be in our […]


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