The Sun will not go supernova but it may still drive us away

25 November 2022

In five billion years, hopefully long after a, hopefully, still extant humanity have departed the solar system for a new home somewhere among the stars, the Sun will become a red giant star. In this late phase of its life, the Sun will expand in size to engulf all the solar system’s inner planets.

While this part of the Sun’s lifecycle will be relatively short-lived — some estimates suggest a mere one billion years — our home planet will have well and truly been obliterated, by the time the Sun shrinks in size again. Unless of course any of our descendants, who stayed home, succeeded in moving Earth further out into the solar system.

The idea has been mooted previously. Even before the Sun becomes a red giant, its gradually increasing heat output, or luminosity, will, in time, make living on Earth ever more uncomfortable.

Such as undertaking will be quite the feat of astronomical engineering. Being able to move the planet will be an achievement in itself, to say nothing of navigating to a suitable spot elsewhere, clear of the larger outer planets. But what happens when the Sun shrinks and cools off again? Do we try and send Earth sunwards again? Perhaps our efforts would be better served finding a Earth-twin planet to live on, orbiting a younger star. And, while we’re at it, figuring out a way of reaching said location in a reasonable timeframe.

At least it’s not something we need concern ourselves with right this minute though. Likewise, the prospect of the Sun exploding as a supernova. It’s something that cannot happen. But what about another star — one in the approximate proximity of the solar system — going supernova? That could be a whole another story.

That’s the question the people at Kurzgesagt explore this month, in their latest video presentation. Again the prospect of a relatively nearby star exploding is not something that will occur any time soon. At present, IK Pegasi, a binary star some one hundred and fifty four light years away, is the nearest possibility, though by the time it is projected to explode, it will be more like five hundred light years distant.

Still as Kurzgesagt explains, risks remain, and even supernovas occurring at some distance could have an impact, no matter how minor, on Earth.