Galileo's telescope
The design Galileo Galilei used in 1609 is commonly called a Galilean telescope. Galileo's most powerful telescope, with a total length of 980 millimetres (3 ft 3 in), magnified objects about 30 times. Because of flaws in its design, such as the shape of the lens and the narrow field of view, the images were blurry and distorted. Despite these flaws, the telescope was still good enough for Galileo to explore the sky. He used it to view craters on the Moon, the four largest moons of Jupiter, and the phases of Venus.
