Let there be light! Introduction to Astronomy ©2016 Human Reformation Project Let there be light! Introduction to Astronomy The history of science involves the history of astronomy and the controversies involved in heavenly motions. ─Unknown

Ancient Civilizations Such as Mesoamerican tribes, the Anasazi, the Babylonians, the Greeks, the Romans, etc. Studied astronomy for religious and societal purposes when to plant crops, harvest them, when to offer sacrifice, etc. developed calendars based on relatively sophisticated astronomical observations

Aristotle 384-327 B.C. Greek Philosopher (Greece) 1st to suggest the Earth-centered solar system model (Geocentric). Couldn’t explain why sometimes planets appeared to move backward, relative to other planets. ©2016 Wikipedia

Ptolemy (90-168 AD) Greek Astronomer (Greece) Created the earth centered model of the solar system (geo-centric system). model stood unchallenged for 1400 years. proposed that Earth was the center of the universe matched with the Church’s teaching that Earth and its inhabitants were the center the universe. closed to any scientific scrutiny. ©2015 Welsh Printing

Ptolemy Accomplishments Greatest Difficulties Compiled 12 Volumes of Greco-Roman Astronomy Determined the distance to the Moon to be 59 Radii (Actual is 60 Radii) Explained orbits by having each planet move along a small circle (Epicycle) whose center traveled along a larger circle, called a deferent, with Earth at its center explaining the changing speeds the occasional east-to-west, or retrograde, motion of the planets ©2016 Wikipedia

Introduced the ellipse Although this scheme came close to accomplishing what he wanted, it still came up a little short. Ptolemy made refinements. placed Earth slightly away from the center of the deferent. (A slightly off-center circle comes very close to mimicking an ellipse.)

Copernicus- 1473 -1543 Polish astronomer (Poland) realized that the motions of the planets could be explained by placing the Sun at the center of the universe instead of Earth. Earth was simply one of many planets orbiting the Sun daily motion of the stars and planets were just a reflection of Earth spinning on its axis. Heliocentric = sun-centered ©2016 Wikipedia

Tycho Brahe (1546 -1601) Brahe was Danish (Denmark) nobleman known for: accurate and comprehensive observations of the solar system. observed a bright “new star” and named it a supernova. ©2016 Wikipedia, Eduard Ender

Johannes Kepler (1571- 1630) German (Germany) mathematician, astronomer, and astrologer. key figure in the 17th century scientific revolution best known for his: Laws of Planetary Motion ©2016 Wikipedia, Unknown Artist

Kepler – 1571 1630 believed firmly in the Copernican system. forced to realization that the orbits of the planets were not the circles demanded by Aristotle and assumed implicitly by Copernicus, but were instead the "flattened circles”. Determined planets did rotate in elliptical paths. ©2016 http://epicworldhistory.blogspot.com/2012/06/johannes-kepler.html

Galileo Galilei (1564 – 1642) Pisa, Italy physicist, mathematician, astronomer, and philosopher played a major role in the scientific revolution. refined his theories on motion and falling objects developed the universal law of acceleration all objects in the universe obeyed. ©2016 Wikipedia, Justus Sustermans

Inventions and improvements: Refracting(light bending) Telescope Galileo Thermometer Gravity experiment at the Tower of Piza Designed mechanism for pendulum clocks ©2014 http://en.academic.ru/dic.nsf/enwiki/7079 ©2009 Hustvedt

Accomplishments mounted a body of evidence that supported Copernican theory and contradicted Aristotle and Church doctrine.  There were Mountains on the moon. Jupiter was orbited by four moons. Sun had spots Venus had phases. ©2015 http://world-famous-people.blogspot.com/2010/08/galileo-galilei.html

Sir Isaac Newton – 1642 - 1727 England Mathematics –created calculus Astronomy – built first practical reflecting telescope. 3 Laws of Motion Light and Color Universal laws of gravitation gravity held planets in orbit ©1688 Sir Godfrey Kneller

Geo-Centric the geocentric model where the Earth is at the center of all the celestial bodies (©2016 Wikipedia). ©2010 http://scienceblogs.com

Helio-Centric the astronomical model in which the Earth and planets revolve around the Sun at the center of the Solar System (©2016 Wikipedia). ©2010 http://scienceblogs.com