There’s no shortage of doomsday theories, but one cosmic threat has long captured the imagination: the looming collision between the Milky Way and its closest neighbor, the Andromeda galaxy. Now, researchers at Durham University have used 100,000 simulations to determine just how likely it is this event could spell the end of Earth — and whether there’s hope of avoiding it.
According to NASA, the Milky Way and Andromeda are hurtling toward one another at a staggering 300,000 mph. A direct hit could ultimately trigger the formation of a vast elliptical galaxy and potentially wipe out life on Earth. But before panic sets in, this is expected to happen at least five billion years from now.
By that point, Earth may already face other existential threats. The Sun is projected to expand into a red giant, possibly engulfing our planet or leaving it a frozen, lifeless rock.
Simulating doomsday
Given the stakes, the Durham research team ran 100,000 simulations to explore different outcomes of this galactic dance. In just 2% of scenarios, a catastrophic head-on collision occurred within five billion years.
In roughly half of the simulations, however, the galaxies passed by each other slowly, gradually spiralling toward an eventual merger, but on a longer timeline of 8 to 10 billion years. In short: the danger may be much farther off than previously thought.
Even if the galaxies collide while Earth is still around, experts say the risk to our planet is minimal. "Even when two galaxies collide, collisions between stars are very unlikely," explained Dr. Till Sawala of the University of Helsinki, the study’s lead author.
Professor Carlos Frenk of Durham University added, "Until now, we thought this was the fate that awaited our Milky Way. We now know there’s a very good chance we may avoid that scary destiny."
One unlikely hero may be helping to steer us clear of disaster: the gravitational pull of the Large Magellanic Cloud, a small satellite galaxy whose influence may subtly shift the Milky Way’s trajectory enough to avert a catastrophic collision.