2. History of Astronomy How have ideas about the solar system and our place in it changed over time? How have ideas about the solar system and our place in it changed over time?

3. Astronomy is the science that studies the universe.

4. Ptolemy 140 CE, Greek wrote the first Astronomy textbook “Geocentric” model “epicycles” His ideas lasted 1400 years

6. Ptolemy epicycles

7. Copernicus 1473-1543, Polish http://upload.wikimedia.org/wikipedia/commons/ f/f2/Nikolaus_Kopernikus.jpg sun First to suggest “heliocentric” model – sun is center of universe

9. What do you think? Why do you think it was difficult for people to accept a heliocentric model (sun centered) over the geocentric model (Earth centered)? Why do you think it was difficult for people to accept a heliocentric model (sun centered) over the geocentric model (Earth centered)? Geocentric modelHeliocentric model

10. Copernicus

11. Tycho Brahe 1546 – 1601, Danish http://upload.wikimedia.org/wikipedia /commons/2/2b/Tycho_Brahe.JPG detailed observations and measurements – tracked orbits

12. Tycho Brahe his ideas combined both geo and heliocentric models  sun & moon revolved around the Earth.  other planets revolve around the sun. tycho

13. Johannes Kepler kepler 1571 – 1630, German assistant to Tycho Brahe supported heliocentric model

14. Johannes Kepler Three Laws of Planetary motion 1.Planets have elliptical orbits 2.Speed of a planet changes during its orbit ------------------------------------------- [ 3. Law of harmonies] http://www.youtube.com/watch?v=a19LTnXkyVQ

15. Galileo Galilei http://todayinsci.com/G/Galilei_Galileo/Ga lileiGalileo-Cresti300px.jpg 1564-1642, Italy “The Father of Modern Science” supported heliocentric model

16. Galileo Galilei sunspots Venus had phases four of Jupiter’s moons 1609 developed a telescope to study objects in the sky moon’s surface was not smooth

17. http://todayinsci.com/G/Galilei_Galileo/Ga lileiGalileo-Cresti300px.jpg Galileo

18. Isaac Newton 1643 - 1727, England 1687 Published book on laws of motion Newton’s Laws explained Kepler’s theories about orbital ellipses of the planets and the motion of the universe

19. Isaac Newton Universal Law of Gravitation The force of gravity depends on the mass of the objects and the distance between them

20. Isaac Newton Universal Law of Gravitation http://www.history.com/topics/enlightenment/videos/beyond-the-big-bang- sir-isaac-newtons-law-of-gravity

21. Edwin Hubble 1889 - 1953, USA discovered that other galaxies existed beyond the Milky Way proved the universe is expanding support Big Bang Theory

22. Edwin Hubble http://www.youtube.com/watch?v=hVApTLE7Csc