While it's impossible to pinpoint the exact date of the Andromeda Galaxy's discovery, we can say it was first observed in the year 964 by the Persian astronomer Abd al-Rahman al-Sufi.

He described it in his "Book of Fixed Stars" as a "small cloud," marking its location and noting its appearance.

However, at the time, it was not understood to be a galaxy separate from our own. It was only much later, in the 20th century, that astronomers recognized Andromeda as a distinct galactic entity and determined its true nature.