👉 Ptolemy, also known as Ptolemy of Alexandria, was an ancient Greek mathematician and astronomer who lived from the 3rd century BC to the 2nd century AD. He is best known for his work "The Book of the Stars" which describes the positions and movements of the stars in the night sky during the summer solstice. The book included a complex system of equations that used trigonometric functions to calculate the positions of the planets, moons, and