While astronomers estimate that the Andromeda galaxy will collide with our own Milky Way galaxy 8 billion years from now, they now believe that another collision will happen even sooner.
The Large Magellanic Cloud will catastrophically collide with the Milky Way in 2 billion years, according to a study published this month in the Monthly Notices of the Royal Astronomical Society. The impact, which they believe is long overdue, has a chance of sending our solar system “hurtling through space.”
Our galaxy is orbited by smaller satellite galaxies, the kind of dance that can go on undisturbed for billions of years. Other times, things take a violent turn, and satellite galaxies can migrate toward the Milky Way until they collide and are gobbled up.
The Large Magellanic Cloud is fairly new to orbiting the Milky Way, entering our corner of the universe 1.5 billion years ago. It’s now the brightest satellite galaxy we have, 163,000 light-years from the Milky Way. Previously, astronomers thought it would hang out in a quiet, long orbit or speed away from the gravity of the Milky Way and move on.
But new measurements suggest that this little satellite galaxy was hiding a big secret, and it has a much larger mass than expected. This means the Large Magellanic Cloud is losing energy, which will trigger it to collide with the Milky Way.
“The destruction of the Large Magellanic Cloud, as it is devoured by the Milky Way, will wreak havoc with our galaxy, waking up the black hole that lives at its center and turning our galaxy into an ‘active galactic nucleus’ or quasar,” Marius Cautun, study author and postdoctoral fellow at Durham University’s Institute for Computational Cosmology, said in a statement.
What does that mean, exactly?
“This phenomenon will generate powerful jets of high energy radiation emanating from just outside the black hole,” Cautun said. “While this will not affect our Solar System, 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 into interstellar space.”
Although 2 billion years sounds like an incredible length of time for us, that’s much less than the age of the universe: 13.8 billion years. The Milky Way galaxy itself is about 13.5 billion years old, so hasn’t it survived galactic collisions before?
“We think that up to now our galaxy has had only a few mergers with very low mass galaxies,” Alis Deason, study co-author and royal society university research fellow at the Durham University’s Institute for Computational Cosmology, said in a statement. “This represents very slim pickings when compared to nearby galaxies of the same size as the Milky Way. For example, our nearest neighbour, the Andromeda galaxy, devoured galaxies weighing nearly 30 times more than those consumed by the Milky Way. Therefore, the collision with the Large Magellanic Cloud is long overdue and it is needed to make our galaxy typical.”
If it doesn’t send our solar system hurtling through space, the galactic show will be something to see from Earth’s perspective. And the researchers suggested that violent events have long shaped the universe.
“Barring any disasters, like a major disturbance to the Solar System, our descendants, if any, are in for a treat: a spectacular display of cosmic fireworks as the newly awakened supermassive black hole at the centre of our galaxy reacts by emitting jets of extremely bright energetic radiation,” Carlos Frenk, study co-author and director for the Durham University’s Institute for Computational Cosmology, said in a statement.