Galileo Galilei was born February 15, 1564, Pisa [Italy]—died January 8, 1642. Galileo's parents were Giulia Ammannati & Vincenzio Galilei. Throughout Galileo's lifetime, he was an Italian natural philosopher, astronomer, and mathematician who made fundamental contributions to the Scientific Revolution. The scientific revolution was a time that challenged the ideas concerning god, reason, nature, and humanity.
During Galileo's lifetime, many people believed in the teaching of Aristotle. In particular, Aristotle taught that heavier objects fall faster than lighter ones. Galileo knew Aristototle was inaccurate. Galileo gathered balls of different weights and sizes and began to roll them down ramps with different inclines. According to space.com, "His experiments revealed that all of the balls boasted the same acceleration independent of their mass."
A common miss conception is that Galileo made the first telescope. That is false. Hans Lippershey created the first telescope (the first one to patten telescope). The first telescope only had three times magnification. The story goes that Hans Lippershey developed the idea after watching two children in his workshop holding up two lenses that made a distant weather vane appear closer. The telescope was called the spyglass.
Anyhow, Galileo improved the telescope. In 1609, Galileo was experimenting with telescope making. He would grind and polish lenses.
A couple after playing around Galileo created a telescope that had a magnification of 20x - without ever seeing the spyglass.