Heliocentric Theory 

The ptolemaic model believed the heavens revolved around the Earth. Aristotle believed the stars and plants were divine moving in perfect circles. Ptolemy had to modify Aristotle’s ideal model to match observations. Ptolemy’s was founded upon Aristotle’s faith. It was physically wrong but accurately predicted orbits. Moslim scholars began criticizing ptolem’s models. Nicholaus copernicus devised the heliocentric theory by 1543. The heliocentric theory was accurate in its  predictions AND physically correct. It revealed the actual structure of the solar system. Space exploration requires exact knowledge of planetary positions. The theory of copernicus was slow to catch on.

Nicholas Copernicus

Nicholas Copernicus was born in Poland in 1473. Copericus developed an interest in astronomy in school. He grew fascinated by the contradictions between Aristotle and Ptolem’s model. At Bologna he observed discrepancies with the model. His theory’s first draft was completed in 1514. His insight didn’t come from Renaissance literature. Cpernicus christen faith provided the basis for the scientific revolution. He believed science was possible because God sustains the universe. He thought a more simple design was the sun at the center. He also made numerous other measurements and astronomical discoveries. He had diverse interests but specialized in astronomy. 

Andreas Veralius 

    

Andreas Vernalius was born in 1514 in Brussels. His father, grandfather, and great grandfather were doctors for the German emperor. He began college in the Netherlands but moved to Paris and became interested in anatomy. He learned of Galen and his critics. A major insight: Galen’s knowledge based on animals not people. No one had checked Galen’s work in 1300 years. Vesalius published a crucial treatise on anatomy in 1543. It gives detailed descriptions of the entire human body. Vesalius innovated: he did what doctors before him thought was beneath them. He provided critical and conductive criticism of anatomical knowledge.

Pencil 

Writing instruments go back to the dawn of mankind. The Romans used an “erasable” wax tablet. Erasable tablets were cheaper than ink and parchment. A large graphite mine was discovered in England. The wooden encasement was developed in 1560 and the modern pencil-making techniques arose by 1600. Pencils are graphite rods eneuced in wood. Pencils make durable markings. They are cheap to make and use. Pencils offer benefits to artists. Artists immediately grasped the benefits of the pencil. The use of graphite in making cannonballs gave the English military advantages. King Henry VII took control over the mine and revicted access. England gained a world monopoly on pencil making.