Many years ago, some measurements made by scientists with the help of the Hubble spatial telescope, indicated that the Milky Way and our neighbour’s, Andromeda, went in a collision trajectory. Many people must think that they’ll crash and it will finish with a magistral explosion between the two galaxies, but what will happen?
In the Local Group (an ensemble of galaxies that are close to us at which have given this name), formed by the Milky Way and about 33 galaxies more, ours and Andromeda are the biggest of them. Andromeda is at the same time the one of the closest galaxies to us, situated currently at 2,5 millions light years, and it is approaching to us at 400 000 km/h. With this data we can foretell that in 4 thousand millions of years the two galaxies will collide. It will take them 2 thousand millions of years more, during which they will finish to fuse completely under the attraction of gravity. Due to the mutual gravitational attraction, the two galaxies are approaching, increased because of the dark matter that surrounds them, which is greatest than the “normal” matter, named baryonic matter too.
For more than one century ago, people have made speculations about how the Milky Way will finish, but now we know exactly how the facts will unwrap.
First of all, they’ll, approach one of the other, motivated because of their high speed, but then, like a spring, they’ll approach another time due to the gravity, and like this a couple or three times. The arms of the Milky Way will deform every time more, until the two galaxies will end to fuse completely and form a single galaxy, bigger and probably elliptic.
But what will happen? The process of fusion will be catastrophic?
Not at all, the fusion will be precisely this. The stars of the two galaxies will mix. Even so, there is so much space between the stars that a possibility of collision between the stars is merely signifiant, but, however, they will change randomly their orbits around the new galactic centre that will form the two black holes that we know they are hidden in the centre of both galaxies (like in many others) when they will fusion in one. In fact, we think that the Milky Way has already fused with many other galaxies smaller than her throughout history.
This is what will happen, nothing of explosions or catastrophes. It would be a very good spectacle to contemplate for a civilisation that would live during this period of time, and even more due to the fact that there would be many other stars tan nowadays in a single galaxy. But, unfortunately, when all this will happen, the Sun will have already burned the Earth and the interior planets of the solar system. For this reason we’ll cannot witness this beauty. We’ll cannot unless we go to another star before the Sun converts the Earth into a hell.