Galileo was born in Pisa, Italy in the late 1500’s. He first became a math teacher even though he had no degree in the subject, and here he began his path to greatness. Galileo the math teacher made his first step into Galileo Galilei astronomy when he demonstrated to his students that Aristotle was wrong about object of different weights falling at different speeds. Aristotle was so popular that Galileo soon lost his teaching job, and so sought work in Padua. It was there that his ideas about astronomy truly began.
He began to study Physics and invented a new measuring device, the compass. He discovered the law of falling bodies and the parabolic path of projectiles. These two ideas were key to astronomy as it progressed. Galileo claimed he had no desire to explore astronomy except a passing support for the theories of Copernicus. Copernicus had proposed that the solar system is heliocentric, that is that the planets rotate around the sun. Aristotle and Ptolemy held that the solar system was centered around the Earth, and even the sun rotated around our home. The model Copernicus proposed for the order of planets around the sun has been proven. And today we know Copernicus was completely correct.
Shortly after the spyglass was invented in Holland Galileo decided to make his own for peering at the night sky. With a magnification of 20, this telescope helped Galileo discover mountains and craters on the moon. He also saw, for the first time, the individual stars that made up the Milky Way. He went on to discover Jupiter’s four largest moons. After publishing this information, he was named the royal mathematician in the court at Florence. No longer having to earn a living teaching, he could spend more time exploring. It took him only 9 months to discover Saturn’s phases. This was another nail in the coffin for Ptolemy’s and Aristotle’s ideas about the solar system.
Galileo had a long standing feud with Aristotle’s beliefs and teachings. Galileo found a great deal of support with other modern scientists who wrote of his work. But the powerful church was inclined to believe Aristotle’s theories which placed man at the center of creation. A Florence priest denounced Galileo Galilei astronomy in 1614. Galileo’s response was a letter stating that science was above the bible. In 1616 Galileo was ordered to stop teaching that the Earth revolves around the sun. Galileo complied, continuing his study of falling objects, comets, and methods to determine longitude at sea based on the phases of Jupiter’s moons. It was upon signing a document stating the Earth is stationary Galileo uttered a famous quote. “I would say here something that was heard from an ecclesiastic of the most eminent degree; “And yet … it moves.”
