What If Earth's Nearest Star System Explodes?

What If Alpha Centauri Went Supernova?

A supernova is a cataclysmic event, when a star dies in a massive explosion. And, Alpha Centauri is easily the nearest star system to our own. So, what would happen if one of its stars went critical?

This is Unveiled, and today we're answering the extraordinary question; What If Alpha Centauri Went Supernova?

When a star reaches critical mass, either over time or by absorbing mass from elsewhere, it goes supernova and releases gamma rays and neutrinos in bursts of radiation. The light from a single supernova can briefly outshine an entire galaxy, such is the incredible amount of energy it produces every second. Scientists measure that energy in units called foes - our sun releases just over one foe in its lifetime, but supernovae can expel a foe every few seconds. Which is pretty devastating for any planet (or any-thing) nearby. In fact, you have to be up to 100 light-years away from a supernova just to be considered ‘safe’.

So, at just over four light-years away, Alpha Centauri is well within striking distance of Earth. But, the distance between us and it also means if one of Alpha Centauri’s three stars went boom, it would take about four years for Earth to see it. In reality, the likelihood of any Alpha Centauri star exploding is extremely low because none of them have enough mass, but if this kind of reaction ever did happen to our (galactically-speaking) next-door neighbour, then Earth is in dire trouble.

The deadly radiation leaving the supernova travels quickly, but only at a fraction of the speed of light - so, we would see the explosion before we felt it, leaving us with perhaps decades to prepare for its arrival. Not that there’s much we could do! Once here, the mix of different rays and energy would eradicate the ozone layer and quickly start destroying life all around the world. The Southern hemisphere would be hit first, but only just. And the rest of the planet would quickly follow suit. Soon anyone (or thing) on Earth's surface is bombarded with charged particles and (thanks to the now-lack of ozone layer) all new levels of UV. It’s mass extinction of life as we know it. Maybe deep-sea creatures survive, but even they could be wiped out.

Aside from radiation, the now-unprotected Earth quickly heats up. The death and destruction is so widespread that even the likes of oxygen-producing plankton are now critically-endangered, so even the air we breathe changes - with nitrous oxide forming in an atmosphere that’s turned into a blanket of toxic smog. In some ways, it’d be like the effects of global warming put on fast-forward. The suddenly increased solar exposure melts the ice caps, causing massive flooding to change the world map forever. In time, the seas boil away turning Earth into a dry husk like Mars or Mercury.

By now, we’re long dead. But everything actually in Alpha Centauri would fair far worse than our own solar system. At such a close proximity to the supernova, the effects - including the emission of almost immeasurably, super-heated atoms - would hit nearby planets, moons and asteroids in a matter of minutes rather than years. Depending on which of the three stars goes supernova, some planets could even be completely absorbed by the expanding, exploding mass. Once the quite considerable ‘dust settles’, the remaining celestial bodies would drift off aimlessly, no longer with anything to orbit around.

It all sounds pretty violent, but a supernova brings some spectacular views, as well. As a supernova, Alpha Centauri could glow almost half as bright as our own sun during the day. At night, it’d generate light thousands of times brighter than our moon. It’d be the lightshow to end all lightshows, only with the caveat of Earth’s own impending doom.

The natural beauty could force through other changes first, though. On a relatively small scale, the endless light would wreak havoc with our circadian rhythms, and severely damage our eyesight. Yes, it might not especially matter (given that we’d all be helplessly waiting for immense radiation to hit) but it would at least contribute to the growing chaos. in fact, the deadly mix of radiation, dramatic climate change and eternal light has fuelled speculation that earthly life could actually rapidly mutate - in a desperate bid to adapt.

On the plus side, it’s thought that a near-earth supernova is something that’s happened before - with science suggesting that they occur within 33 light years of us once every 240 million years. So, Earth itself can (and would) survive. There are theories that the last one triggered a mass extinction, but there’s also speculation that it happened so long ago that the effects of another star’s supernova were actually what turned our planet into a life-supporting environment in the first place.

So, it’s a question of extremes. Were the closest star system to our own to explode, it could be the ultimate ‘end of days’ or the beginning of a literally bright, completely unpredictable future. And that's what would happen if Alpha Centauri went supernova.