According to NASA, the Milky Way and the Andromeda galaxy will collide, forming a new elliptical galaxy.
According to the organization, they move towards each other in what is predicted to be a collision of galaxies, this due to gravity that causes both to attract each other. While they are 2.5 million light years apart, they are also getting closer and will eventually merge within 4 to 7 billion years.
Despite the union between the Milky Way and Andromeda, the Earth is not in danger
This encounter is predicted to take place in about 4 billion years, resulting in the Sun being flung into a new region in our galaxy; However, the Earth and the Earth would not be in danger of being destroyed.
Andromeda has more stars, more mass and a greater physical extent than the Milky Way in three dimensions. It occupies a larger angular extent in our sky than six full moons, and it is moving in our direction, causing a collision that would have to occur 4 billion years in our cosmic future to leave only one giant galaxy at its core: Milkdromeda.
But why will it happen?
We understand that the Universe has been expanding, and the rate of expansion is determined by the overall energy density of space, on average. Energy density includes energy in the form of: normal matter, dark matter, radiation (such as photons), neutrinos, and dark energy.
On the other hand, the Universe, even as it expands, also gravitates, and all forms of energy not only bend the local neighborhood of the space they occupy, but affect the overall expansion rate of the Universe, which means a push and pull. of what is found in the universe.
Now, the Universe is full of structure: galaxies, groups of galaxies, rich galaxy clusters, and vast cosmic voids that separate them. When we map it in sufficient detail, we find a network of web-like structure in our Universe, where galaxies form along the strands of that web and, more richly, at the nexus or intersection of those various strands.
Matter is preferentially attracted to these excessively dense regions, causing it to flee from the “in-between” regions, creating vast cosmic voids, and the difference between structure-rich and structure-poor regions becomes more marked as time passes.
The reason for this goes back to the Big Bang itself. It turns out that, on average, the Universe is filled with the same amount of all forms of energy, including normal matter and dark matter, everywhere. But the truth is that the Universe was born littered with tiny imperfections: overdense and underdense regions, at the level of just a few parts per 100 thousand everywhere and that with gravitation causes the universe to join or separate galaxies.
Milky Way and Andromeda were going to unite anyway
So the reason Andromeda and the Milky Way will one day merge (and yes, they really are on a collision course) is because back in the early stages of the Universe, more than 10 billion years ago, we were all gravitationally pulled together. to become human beings, and eventually, if given enough time, all the galaxies in our local group will collide and merge, although this process should take several tens of billions of years, several times the current age of the Universe, to be completed.