Bright star Betelgeuse poised to explode into a supernova visible during the day

ONE of the brightest stars in the night sky may be about to explode in a rare cosmic supernova that would be visible during the day, and cast shadows on the Earth at night.

Betelgeuse – roughly pronounced as “beetlejuice” – is the bright orangeyred dot that sits on the shoulder of Orion, and was until recently one of the easiest stars to spot in the night sky.

But since October, the star has been dimming to the point where it is now difficult to see with the naked eye.

Astronomers believe this suggests a supernova is imminent.

If it did explode, Betelgeuse would become as bright as a full Moon for a few months, casting its own shadow at night, before fading away to nothing, and altering the outline of the Orion constellation forever.

However, the explosion would not be harmful. The star is around 600 light years away, so any explosion seen now would have occurred 600 years ago. Any particles spewing from the explosion may reach our solar system in about six million years but would have a minimal impact because the heliosphere – the Sun’s magnetic bubble that encompasses all the planets – is powerful enough to deflect them.

Betelgeuse is a red supergiant with a mass 12 times that of our Sun.

It burns so brightly that it is dying after just eight million years. By contrast, our Sun is already five billion years old. After using up all its hydrogen fuel long ago Betelgeuse is now fusing heavier elements inside its core to the point where iron is being created. But the fusion of iron is the death knell – energy is being absorbed and soon the star’s huge gravity will cause it to collapse, generating a giant shock wave that will rip it apart as a spectacular supernova.

Betelgeuse is a variable star, which means it becomes brighter and dims in cycles. One lasts roughly six years and another every 425 days or so.

The two cycles are currently overlapping in a dimming period, but if the star does not brighten again at the end of it, a supernova could be on its way.

“The biggest question now is when it will explode in a supernova,” Sarafina Nance, an expert on Betelgeuse at the University of California Berkeley, said on Twitter. “It would be so incredibly cool.”