There was no science in the Middle Ages. Science is an attempt to explain natural phenomena in this world, and man of the Middle Ages knew how everything happened–God did it! When Renaissance man started looking for scientific answers, he had to go back to famous Greek and Roman scientists. Ptolemy was a Greek astronomer. Astronomy was the first big science studied. Ptolemy had definite ideas about the world and the universe and how it all fit together. He said he could prove the Geocentric Theory of the Universe. (Geo- = Earth and -Centric = Centered; therefore, Geocentric means "earth centered.") Everything is supposed to go around the earth except some fixed stars, according to Ptolemy. Some Greeks thought the earth was moving but Ptolemy said if the earth was spinning, it would pick up speed and spin us off. Besides if you throw something up, it comes down in the same place and if the earth was spinning it would come down somewhere different, cuz the earth had moved underneath it. Actually, the truth is that everything is moving at the same speed. The church adopted the geocentric concept cuz it meant that God made us so neat he put us at the center of the universe.
Leonardo da Vinci was an artist, military engineer, etc. During his time, science was thought to be heretical, so he wrote stuff in his notebooks in a secret code (backwards–which, by the way, is not that difficult–I personally do it very well). He said things like the moon has no light of its own. He said you could make a submarine but he only described, he wouldn't draw plans for it cuz then people would use it for war. He drew planes. But since his notes were funny, nobody found out what he was thinking until much later so he had no impact during his time.
Copernicus was born in 1473. He was Polish and educated in Poland then went to Italy to teach astronomy. He said if the earth was the center, why were the planets so weird? Planets make epicycles around us cuz they don't go around the sun at the same speed we do. He stated the Heliocentric Theory. (Helio- = sun and -Centric = centered; therefore, heliocentric means "sun-centered.") He wrote Concerning the Revolutions of Heavenly Bodies, but it wasn't published until after he died cuz he was afraid of the church. The printer even put a fake 1st chapter in it to excuse his printing of this book. The Catholic church didn't do anything for awhile but finally came down hard on it in the 1600s.
Tycho Brahe was Danish but studied in Germany. He tried to get a dueling scar to appear dashing (all the rage of the day!). His opponent cut off his nose instead. He wore artificial noses (gold, silver) with glasses. He had no telescope (not invented yet). So to plot stars, he had to lie on his back on the ground. Denmark was a good place to observe cuz of the clear atmosphere. Brahe believed Ptolemy and kept plotting but never used his figures to prove anything. Kepler was his lab assistant who used Brahe's figures and said planets go in ellipses.
Galileo was an Italian. He discovered the Law of the Pendulum by age 20. His Law of Uniform Acceleration said everything was pushed on by a constant force. Considering air pressure, your body should collapse cuz it weighs more. But because the air pressure is pushing on every square inch of your body all over, you don't collapse but maintain shape. He invented the first telescope, glass lenses in a tube. He saw the moon had light from the sun and found valleys and mountains on the moon. He saw moons going around Jupiter. He saw the moon was the only thing going around us. Soon the church shut him up. So he wrote Dialogue Concerning the Two Chief Systems of the World. It was a little "discussion" between 2 astronomers discussing the heliocentric and geocentric theories. Galileo actually never came out loud and said which he believes. But the church called him and made him recant which he did very unwillingly and probably claimed he was still right under his breath! The Catholic church finally forgave him in the 1970s. (Right on top of things, huh!!)
Newton was born the year Galileo died. 1661-1665 were his major years of discovery. He discovered calculus, the Law of Composition of Light (with prisms), the Law of Gravity. He was then given a fat government job and took it easy for the rest of his life. He didn't discover gravity–people knew things fell towards earth. But he put the math behind it. It works cuz of mass (amount of stuff) and weight (how much the earth pulls down on the stuff). Things with more mass are going to fall faster cuz they're being pulled harder by the earth which has the biggest mass of all. (Probably the easiest explanation you'll ever get!) By the way, the apple really did fall on his head, it's not a fable!
People were giving up on religion. People started thinking God was like a master watchmaker–he wound us up and let us go. These people were called Deists. Yeah, there's a powerful god who started things but we're on our own now. Now people explain the creation of the universe with the Big Bang Theory cuz of the Doppler effect of sound and light waves. (Doppler effect of sound–things change pitch as they go by us. It wasn't discovered until after the invention of the railroad cuz nothing ever went by people fast enough to change pitch so dramatically as a train whistle–any more questions on this, ask Stockmyer.)
Other people invented things for science. Otto von Guericke invented an air pump which produces a vacuum. Air pushes 15 pounds per square inch on your body. A vacuum takes away that pressure. Leeuwenhoek invented the microscope. Lots of neat stuff is happening now that people have the time!