In 4 billion years, when the Milky Way galaxy collides with the Andromeda Galaxy, the distance between the stars will be so vast that none of the 1.3 trillion stars are expected to collide.
TL;DR
In roughly 4 billion years, the Andromeda Galaxy and the Milky Way will collide, creating a new supergalaxy. This galactic merger will not result in stars colliding due to the vast distances between them, but the supermassive black holes at the centres of both galaxies will eventually merge. While the solar system might get flung farther from the galactic core, there’s also a chance it could be ejected entirely. Even though life on Earth would have ended by then due to the Sun’s increasing heat, this cosmic event would offer a stunning view of the changing night sky.
After reading the article, Reddit user Harry, with over +6.5k upvotes, commented: “It’s not direct collisions that are the issue. It’s the disruption to the normal gravitational systems and orbital paths. A planet that was in the goldilocks zone for liquid water and life could get affected by another passing star system enough to move it sufficiently out of its normal orbit to have planet changing effects.”
Don’t forget to join the discussion below!
___________
The Andromeda Galaxy is hurtling toward the Milky Way at an astounding speed of almost a quarter of a million miles per hour. It is the closest significant galaxy to the Milky Way and, at a distance of 2.5 million light years, it’s also the farthest object visible to the naked eye. As the two galaxies draw nearer, chaos will ensue, with vast quantities of dust, rocks, asteroids, planets, and stars flung in all directions, making the scene look like a colossal cosmic pinball game. Eventually, this collision will form a new galaxy known as Milkomeda.
Until 2012, scientists were uncertain if the collision between the two galaxies was inevitable. However, researchers using the Hubble Space Telescope to track the motion of stars within Andromeda, with an unprecedented level of precision, determined that the galaxies are indeed on course to collide in roughly 4 billion years.
Collisions of this magnitude are not unusual given the long lifespans of galaxies. Simulations suggest that the resulting galaxy will resemble a giant elliptical galaxy, which lacks the distinctive spiral arms or structured core found in galaxies like our own.
Andromeda is home to around one trillion stars, while the Milky Way contains approximately 300 billion. Despite the sheer number of stars, the distance between them is so vast that direct collisions between individual stars are highly unlikely. For instance, the closest star to our Sun, Proxima Centauri, is 4.2 light years away.
If the Sun were represented as a ping pong ball, Proxima Centauri would be a pea located about 680 miles away. Even in the densest regions near the galactic centres, stars remain around 100 billion miles apart, making it improbable that stars from the two merging galaxies would collide, although some stars could be flung out into space.
What happens to the black holes during the Andromeda-Milky Way collision? Both galaxies harbour supermassive black holes at their centres. Over millions of years, these black holes will gradually spiral closer together and eventually merge near the centre of the newly formed galaxy.
When they come within a light year of each other, they will begin to emit strong gravitational waves, which will release orbital energy and bring them even closer until they merge completely. This merger could potentially ignite a galactic nucleus by absorbing surrounding gas, unleashing a tremendous amount of energy.
So, what does the future hold for our solar system? Current predictions suggest there is a 50% chance that, in the new merged galaxy, our solar system will be pushed out to a distance three times further from the galactic core than its present location. At the moment, the Sun is situated in the Orion Spur, a smaller branch of the Milky Way’s spiral arms. If the solar system were ejected further, it would likely end up at the very edge of this arm. Additionally, scientists estimate there is a 12% chance the solar system could be completely flung out of the galaxy. Fortunately, by the time any of this happens, humanity will have long since vanished. Even if the solar system were ejected, it would likely remain undisturbed, with no significant effect on the Sun or the planets, unless we engage in large-scale planetary engineering.
By the time Andromeda and the Milky Way collide, Earth’s surface will have already become far too hot for liquid water to exist, as the Sun’s luminosity will have increased, ending life on Earth. Nevertheless, the planet will still be part of this galactic merger, and its view of the universe will be forever altered. If we could somehow observe the night sky from the scorched Earth or from the far reaches of our solar system, we would see Andromeda growing larger over time. In around 4 billion years, it could stretch across the sky from horizon to horizon, like a beautiful, ethereal band of light.
