Scientists believe that Andromeda and the Milky Way will eventually collide, but it is currently estimated to occur in around 4 billion years. This number comes from observations and calculations of their current trajectory and distance from each other. However, simulations suggest that the collision may not be head-on and could even be avoided entirely. As technology and astronomical knowledge advance, our understanding of these celestial events might evolve, and more precise predictions may emerge in the future.