Astronomers observing the Andromeda Galaxy would currently see it as it exists today, years before the predicted collision with the Milky Way. This collision is expected to occur in about 3 to 4 billion years, resulting in the merger of the two galaxies into a larger elliptical galaxy.
The Andromeda Galaxy and the Milky Way are two major galaxies within our local group that are predicted to collide in the future. The approximate mass of each galaxy is 800 billion solar masses, with a separation of about 2.5 million light-years between them.
According to physics and computer simulations, these galaxies are on a collision course due to the gravitational forces between them, and their eventual interaction will lead to the formation of a larger elliptical galaxy.
While they are currently moving toward each other at 75 miles per second, astronomers looking at the Andromeda Galaxy would see it as it appears today, due to the immense distances involved and the time it takes for light to travel from Andromeda to Earth.
Initially, the collision will begin with Andromeda approaching the Milky Way, and after a complex interaction involving new star formation and reshaping of the galactic structures, the cores of the two galaxies will form bright lobes.
Over a timeframe of 3 to 4 billion years, the merged galaxies will form an elliptical galaxy that will be significantly larger and have a different structure compared to their original spiral forms. Noteworthy is the fact that the Sun's position may change throughout this sequence of events as the galaxies readjust orbits of their stars.