The future collision of Andromeda and milky way are known by astronomers because ; ( C ) Astronomers have observed their movements over time
Andromeda also known as messier 31 is a spiral galaxy that appears as a milky blur when viewed from the earth and it is believed to be slightly over 2.5 million years old.
Astronomers predict that based on its movement and the movement of the Milky way there is most likely going to be a collision in future between the Andromeda and milky way.
Hence we can conclude that The future collision of Andromeda and milky way are known by astronomers because Astronomers have observed their movements over time
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