Inevitable Galactic Collision Sooner Than Expected

Astrophysics researchers from Durham University, in the United Kingdom, have predicted that another galaxy will definitely collide with our Milky Way galaxy far sooner than expected, an event which will cause our Solar System to hurtle through space. 

Durham University Institute for Computational Cosmology postdoctoral fellow Marius Cautun comments, “There is a small chance that we might not escape unscathed from the collision between the two galaxies which could knock us out of the Milky Way and to interstellar space.”

More specifically, scientists expect that the Milky Way will collide with the Large Magellanic (LMC), which is a satellite galaxy to our galaxy, within the next 2 billion years.  This is much sooner than had been expected about the Milky Way’s collision with the much larger neighboring Andromeda Galaxy, which is expected in the next 8 billion years. 

Now, that might not seem like it is very “soon” but Cautun goes on to explain that although 2 billion years is extremely long in terms of a human lifespan, it is actually very short in terms of the cosmic timeline.

The Large Magellanic Cloud is our Milky Way galaxy’s brightest satellite galaxy and it only entered into our orbit within the last 1.5 billion years.  At a distance of 163,000 light-years from the Milky Way, astronomers have long believed that LMC would either orbit the Milky Way for several billion more years or—because it is actually moving very quickly—escape from the gravitational pull of our galaxy all together.

The most recent measurements, however, suggest that LMC has perhaps twice as much dark matter than we had previously thought. Researchers now say this larger-than-expected mass is losing energy rapidly and will inevitably collide with ours. 

It is quite common for galaxies, like ours, to be surrounded by a group of smaller, satellite, galaxies—smaller galaxies which orbit around the larger one—kind of like how bees are always swarming around their hive. Most of the time, these satellite galaxies have a simply quiet life and orbit around their host galaxy for several billion years.  Once in a very long while, though, the smaller galaxies sink to the center and collide with their larger host, which actually devours the satellite galaxy.