Galileo Galilei made immeasurable contributions to math and several sciences.  He became the “Father of Modern Science” as a result of his many discoveries and revolutionary hypotheses.  Galileo’s new theories challenged the current way of thinking, sparking the Scientific Revolution.   Some of his most famous scientific accomplishments are his popularizing of the heliocentric theory, his telescope, and his observations of other planets.   

The Heliocentric Theory is the idea that the sun is at the center of the solar system.  In Galileo’s time this seemed as illogical as it was blasphemous.  The geocentric theory, stating that the Earth is the center of the Universe, was an ancient, widely accepted belief.  Notable thinkers such as Aristotle and Ptolemy acknowledged this as the truth, and the Catholic Church endorsed this belief, stating that God purposefully placed the Earth in the center of the Universe.  Galileo was called a heretic for defending Copernicus’s notion that the Earth revolved around the Sun.  However, he was able to firmly establish the heliocentric theory as a possibility, later leading it to replace the geocentric theory.  This movement also forced others to question that which they had already decided to be fact.  This new age of questioning longstanding ideas became known as the Scientific Revolution.

Galileo was able to observe distant planets because of the improvements he had made to the standard telescope.  In 1609, he created the first refracting telescope.  This new telescope used converging lenses to condense light made billions of light years away into a small image on the telescope’s lens.  With it Galileo was able to make several discoveries about other planets.  He found that Venus, like the moon, rotated and had different phases as a result of its reflecting the sun’s rays.  Galileo concluded that such phases would be impossible if the Sun and Venus revolved around the Earth.   Galileo discovered Saturn’s rings, though he never fully understood them.  He was also one of the first to observe Neptune.  Galileo, however, wrote that Neptune was one of several dim stars in that part of the solar system, not realizing that its size or status as a planet.  His other notable observations include his notes on sunspots, his discovery of craters on the moon, and his finding of several stars in the Milky Way Galaxy that cannot be seen without a telescope.  Overall, Galileo is best known for his discoveries in astronomy and physics and his creation of the scientific method