The formation of the solar system, of the Sun, and the life that came afterward on Earth may actually be a consequence of a collision between the Milky Way – our Galaxy, and a smaller Galaxy, which is called Sagittarius. It was found in the 1990s, and it seems to be orbiting our Galaxy.
Astronomers were aware of the fact that Sagittarius smashes the disc of Milky Way when it orbits around the core of the Galaxy, which is a result of gravitational forces. Studies have shown that Sagittarius, which is a dwarf galaxy, has an impact on how stars move in the Milky Way. Some people say that the 10,000 times bigger Milky Way’s spiral structure is actually the result of three known crashes with Sagittarius from the past 6 billion years.
There is a new study that uses data gathered from the ESA’s Gaia. It showed what kind of influence Sagittarius has on the Milky Way, and it also showed that it might be more important than we initially thought. The ripples, which were caused by the collisions, appeared to have triggered major star formation processes, one of them which actually coincides with the formation of the Sun, around 4.7 billion years ago.
Tomás Ruiz-Lara, astrophysicist, said: “It is known from existing models that Sagittarius fell into the Milky Way three times—first about five or six billion years ago, then about two billion years ago, and finally one billion years ago. When we looked into the Gaia data about the Milky Way, we found three periods of increased star formation that peaked 5.7 billion years ago, 1.9 billion years ago and 1 billion years ago.”