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Supermassive star Betelgeuse, a red giant, now exists in one of its final phases before transforming into a supernova. When it finally blows, what will happen, and how will it impact us on Earth?
Betelgeuse, as part of the constellation Orion, is changing. In the past 15 years, the star has shrunk by 15% in size. The star’s brightness in the sky has not changed, and it remains one of the most visible stars from planet Earth. According to Daily Galaxy, retired Berkeley physics professor Charles Townes (who invented the laser) says, “To see this change is very striking. 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.”
As a red giant, Betelgeuse is understood to have a short but violent lifespan, totaling a few million years at most. Such stars inevitably burn their hydrogen fuel too fast and end up sputtering out in partial collapses and restarts. We don’t know how many times Betelgeuse has collapsed and refueled itself through another element. This could be the last time. Betelgeuse is expected to explode into a supernova at any point within the next 100,000 years. It’s already one of our brightest stars, and the supernova phase could make it was visible as our Moon. This phase would last for about a year.
What would happen if Betelgeuse goes supernova tomorrow? We wouldn’t notice right away since this red star is 600 light years away. But there would be noticeable effects:
(1) Medium points out that Betelgeuse’s supernova phase could be so bright that it would immediately outshine every other star in the sky.
(2) We’d probably be able to see Betelgeuse during the day (just like we can see Venus), but we’d have to know where to look.
(3) At night, Betelgeuse would be impossible to ignore and be as bright to the naked eye as a quarter moon. A different supernova observed in the year 1006 was bright enough to cast shadows at night.
(4) Betelgeuse sits far enough away that an explosion won’t harm us physically. A supernova must be 25 light years or closer to harm us during an explosion.
(5) In the very rare event that Betelgeuse’s supernova transformed into a hypernova, it could generate gamma-ray bursts that “would result in gamma radiation with an energy equivalent to 1,000 solar flares simultaneously – enough to threaten Earth by production of nitrous oxides that would damage and perhaps destroy the ozone layer.” A hypernova would also eventually collapse into a black hole (instead of a neutron star). This probably will not happen to Betelgeuse at all, let alone in our lifetimes, but you can read about the process at this link.