Astronomers with NASA have announced that they have predicted "with certainty" that the Milky Way galaxy where we live and the Andromeda galaxy will collide. The astronomers predict that the collision will happen 4 billion years from now. Interestingly, the collision will certainly change our galaxy according to the astronomers, but the earth and our solar system aren't in danger.
The Hubble Space Telescope was used to capture data allowing the prediction to be made. The Andromeda galaxy is 2.5 million light-years away, but is coming closer to the Milky Way due to the mutual pull of gravity between the two galaxies and dark matter between them. After the initial collision in 4 billion years, the scientists predict it will take another 2 billion years for the galaxies completely merge.
The galaxies will eventually merge into a single elliptical galaxy similar to others seen in the local universe. Even more interesting is that the Andromeda galaxy and the Milky Way are expected to eventually collide with a third galaxy called the Triangulum galaxy that could also merge with the original pair. Check out the video to see what the scientists believe the collision could be like.