Just last year, astronomers definitively announced that the Andromeda Galaxy and the Milky Way will collide – albeit not for another 4 billion years.
It sounds dramatic, but the collision will be more like an encounter between the two giants. Andromeda contains close to a trillion stars, more than twice as many as the Milky Way’s 400 billion or so stars. The distances between these stars are so vast that collisions between them are unlikely. Instead, gas clouds will collide, triggering copious star generation in the universe’s newest supergalaxy, Milkomeda.
Milkomeda’s strong gravitational field could affect our solar system greatly, however. There’s a 50 percent chance that the sun will be hurled farther from the center of the supergalaxy.
The collision won’t affect life on Earth, as the planet will already be uninhabitable by then. In 4 billion years, Earth’s temperature will exceed 570 degrees F due to the sun’s increasing radiation as it expands. The oceans will have boiled away long ago, and only lifeless deserts and salt plains will mark the seas that once enabled life on the planet.