1. Scientists’ Contributions to Our Understanding of the Solar System Assignment #38 – Helio/Geo-Centric Models

2. Greek Myths tell about… A god named Helios, who was “god of the Sun” A goddess named Gaea (Gee-a), AKA “Mother Earth, “ the protector of Earth and mother of the Titans and humans)

3. The Greeks Noticed that stars moved in fixed patterns as they seemed to move across sky – except for 5 that seemed to “wander.” Determined that these 5 were not stars Gave us the word “planets” which means “wandering stars” Believed in geocentric system

4. geo - means of Earth; related to Earth -centric means Earth in the center What does the word ‘geocentric’ mean? Well, if… and… then… geocentric means in the center

5. Copernicus Polish Astronomer 1500s Believed in heliocentric system http://www.bun.kyoto-u.ac.jp/phisci/Gallery/copernicus.html http://www.aip.org/history/esva/catalog/esva/Copernicus_Nicolaus.html For images of this astronomer, go to: Source of photo, which is in public domain: Wikipedia

6. helios - means of the sun; related to the sun -centric means sun in the center What does the word ‘heliocentric’ mean? Well, if… and… then… heliocentric means in the center View an interesting phenomenon in an animation of our heliocentric system: http://www.astro.utoronto.ca/~zhu/ast210/heli centric.html http://www.astro.utoronto.ca/~zhu/ast210/heli centric.html

7. helios - means of the sun; related to the sun -centric means sun in the center What does the word ‘heliocentric’ mean? Well, if… and… then… heliocentric means in the center View an interesting phenomenon in an animation of our heliocentric system: http://www.astro.utoronto.ca/~zhu/ast210/heli centric.html http://www.astro.utoronto.ca/~zhu/ast210/heli centric.html

8. Galileo, Italian Astronomer 1500s and 1600s Believed in heliocentric system & supported Copernicus Improved the telescope to view objects in sky For images of this astronomer and his telescope, go to http://www.aip.org/history/esva/catalog/esva/Galileo_Galilei).html Image of Galileo, which is in public domain: Wikipedia

9. What did Galileo see in the sky to make him believe in heliocentrism? 2. The moon has mountains, valleys. It isn’t smooth and perfect. 3. Jupiter has moons, so everything does not orbit around Earth. 1. Venus has phases (like the moon), so it must orbit the sun.

10. 1633 at age 70, Galileo had to recant his findings before the Church - “must altogether abandon the false opinion that the sun is the center of the world and immovable, and that the earth is not the center of the world, and moves, and that I must not hold, defend, or teach in any way whatsoever, verbally or in writing, the said false doctrine, and after it had been notified to me that the said doctrine was contrary to Holy Scripture.”

11. Newton, English Scientist Recognized that two factors keep planets in orbit: – Inertia (1 st law of motion) – Gravity Fabulous pictures on this site: http://www-gap.dcs.st-and.ac.uk/~history/PictDisplay/Newton.html Source: Wikipedia/pulic domain

12. 1. What does “geocentric” mean? Draw and label a diagram of this model of the solar system. 2. What does “heliocentric” mean? Draw and label a diagram of this model of the solar system. 3. What did the Greeks believe? 4. What scientists believed in the heliocentric model? Write these questions out and answer them AFTER we read the textbook together in your journal.