Historical Astronomy STARRY STARRY NIGHT

400 B.C.E. noticed that some of the celestial objects moved relative to the rest. They counted moving objects- Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. They were called planets (Greek- to wander). Aristotle 7

He believed that the earth was motionless and located at the center of the universe, universe. He believed there was a celestial sphere containing all the stars, which revolved around the earth every 24 hours. To explain the planets, he supposed that each of the 7 objects had their own sphere. geocentric

Earth

1473 A.D. Polish astronomer Nicolaus was born. He spent over 30 years of his life observing and studying the planets and stars. In 1533 he completed a book entitled Revolutions of the Heavenly Spheres. However, his observation and studies led him to a sun-centered universe, universe. Fearful of ridicule he waited until hours before his death in 1543 to publish the book. Copernicus heliocentric

Sun

1576 A.D. Danish astronomer who lost part of his nose in a duel with another student in 1566 and replaced it with a gold and silver one, was given the Island of Hven, near Copenhagen by King Frederick II of Denmark. He was given funds to test Copernicus’ ideas. Over the next 20 years he studied the changing positions of the planets. He witnessed a nova (new star, Crab nebula) in 1572 and a comet in Tycho Brahe

1600'S (early) German mathematician Johannes, using Brahe’s observations, determined that Mar’s orbit could only be explained by an. He then inferred that all the orbits must be elliptical. Kepler ellipse

Sun

1616 A.D. Italian, Galilei, was the 1st to use the telescope to look into the heavens. He spoke about many of the traditional beliefs, saying they were inaccurate. Using the telescope he was able to see craters on the moon, sunspots, individual stars of the Milky Way, he observed the phases of Venus (which occur over a 2 year period), he saw the rings of Saturn, and he was able to see 4 moons of Jupiter as they revolved around it. Galileo

During his research he was unable to speak openly about this theory due to the religious implications. He published a book (in Italian, not the usual academic Latin) stating that the earth and all the planets moved around the sun (Copernican theory) which annoyed the Aristotelians. He reached this conclusion (Heliocentric Universe) due to the fact that it explained the motions of celestial bodies the easiest.

The Catholic Church was afraid of a scandal that might undermine its fight against Protestantism, and so took repressive measures. It declared Copernicanism “false and erroneous” and commanded Galileo to never again “defend or hold” the doctrine. He acquiesced.

1632 A.D. Galileo published a second book, Dialogue Concerning the Two Chief World Systems, with the permission of the new pope. He just had to promise to present both sides without bias. His book convinced many that the Copernican theory was correct. The pope had second thoughts about the book and had Galileo brought before the inquisition. The church put him under house arrest until his death in 1642.

1642 A.D. The same year Galileo died Isaac was born in Woolsthorpe, England. Newton

1665 A.D. The deadly bubonic plague raged through London, killing hundreds of people every day. Isaac Newton was a 22-year-old student and teacher at Trinity College in London. He was forced to return to his mother’s farmhouse.

Over the next 18 months Newton proved that the force that pulls an apple to the ground is the same force that keeps the moon in orbit around the earth. He was also able to show that this force keeps the planets in their orbits around the sun.

Additionally, he discovered the 3 Laws of motion, the secrets of light and color, and a branch of mathematics called calculus (needed to prove the laws of motion and gravity). He was also the 1st to use a reflecting telescope.