You probably know Betelgeuse as that star with the weird name, but it’s of particular interest to astronomers right now. It’s a red supergiant in Orion many thousands of times brighter than the sun, and it’s dying. Astronomers expect Betelgeuse will go supernova in the next 100,000 years, and it turns out this star might be much closer to Earth than we thought. Don’t start building a supernova-proof bunker just yet — it may be closer, but it’s still not dangerous.
Betelgeuse made headlines recently with speculation that it may be on the verge of exploding (it’s the red star on the left in the image above). This was based on some very bizarre changes in the star’s brightness. Since we don’t know exactly how a star like Betelgeuse looks immediately before it dies, this was not an unreasonable hypothesis. However, astronomers now believe it’s much more likely that the star simply released a cloud of gas that partially obscured our view. And that makes sense — supergiant stars are so hot and energetic that they shed huge amounts of matter in their solar wind.
This event reminded astronomers there’s still a lot to learn about Betelgeuse before it explodes. Rather than wait another 99,000 years or so, a team from The Australian National University (ANU) took a look at the data we have on Betelgeuse to get a better handle on its size, mass, age, and distance from Earth. Most of what they found jives with previous estimates, with the notable exception of the size.
This comparison image shows the star Betelgeuse before and after its unprecedented dimming.
In the past, astronomers believed Betelgeuse was just under a billion miles (1.5 billion kilometers) in diameter. However, using data from the Department of Defense’s Coriolis mission, the team claims it’s closer to 1 billion kilometers. That’s still huge; in fact, Betelgeuse is so big that astronomers can see the disk of the star rather than a mere point of light. The size of that disk is a function of its size and distance, and the new size estimate means it would also need to be closer to account for its incredible brightness. It’s actually the tenth brightest star in the sky.
The team estimates that if the new reading is correct, Betelgeuse is about 25 percent closer than we thought. Luckily, that’s still about 530 light-years, which is too far away to fry Earth when it eventually explodes. The study also suggests that the explosion is still a long way off. If the new calculations are right, the model predicts Betelgeuse is still in its carbon fusion stage. That stage lasts about 100,000 years before the star moves to heavier elements. So, we’ve got time and distance, which is nice. Of course, we will have to wait on other teams to verify these findings before Betelgeuse’s position in the cosmos is officially updated.
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