Who invented the first practical astronomical telescope?

Galileo Galilei

Galileo Galilei, by improving the design of the telescope, opened a new window onto the universe in the early 17th century. With this instrument, he made groundbreaking discoveries, such as the lunar craters and the four largest moons of Jupiter. These observations strongly supported Copernicus's heliocentric model, challenging the prevailing geocentric beliefs. Galileo is often called the "father of modern astronomy" for his pioneering contributions to astronomical observation.