Apocalypse when? Our galaxy may not collide with another after all

By Dean Murray

Our galaxy may not collide with its neighbor after all, suggests new research.

For over a century, astronomers believed a dramatic collision between the Milky Way and Andromeda galaxies was inevitable.

But new research using data from NASA’s Hubble Space Telescope and ESA’s Gaia observatory has cast doubt on that fate.

An international team led by Till Sawala of the University of Helsinki analyzed the most precise measurements yet of both galaxies’ motions and ran 100,000 computer simulations to forecast their future.

The results showed only about a 2% chance the galaxies will collide in the next 5 billion years, and only a 50-50 chance of a merger over the next 10 billion years.

The simulations factored in 22 variables, including the gravitational influence of nearby satellite galaxies like Andromeda’s M33 and our own Large Magellanic Cloud.

In about half the scenarios, the two galaxies pass close but don’t merge, instead continuing a kind of cosmic dance for billions of years.

In the other half, they eventually collide and form a new, elliptical galaxy, but not for at least 7-8 billion years.

“Even using the latest and most precise observational data available, the future of the Local Group of several dozen galaxies is uncertain,” Sawala said. “We find an almost equal probability for the widely publicized merger scenario, or, conversely, an alternative one where the Milky Way and Andromeda survive unscathed”.

However, NASA says any scenario may not matter to Earth-based humans.

They add: "Considering that the warming Sun makes Earth uninhabitable in roughly 1 billion years, and the Sun itself will likely burn out in 5 billion years, a collision with Andromeda is the least of our cosmic worries."