1. The Discovery that the Earth is Round By: Courtney Dussinger, Kathryn McLaughlin, Maggie Lamb & Maddy Sova

2. Thoughts before the discovery The most popular theory before the idea that the earth could be round: The Flat Earth Theory Idea that the earth was a flat object rather than spherical Picture an island floating in space This theory was commonly believed around the world in many different cultures. These include Ancient Egypt, Babylonia, China, and Greece

3. Reasoning behind the Flat Earth Theory Religious reasoning Many people took the Bible literally: the world is said to have “four corner”; therefore it would be a square Logic behind theory Flat earth seemed to be true from what humans could see around them until it was questioned in 4 th century B.C.

4. The Discovery In 192 BC Eratosthenes claimed that the earth was round. He discovered this based on his observations of shadows. He recorded the shadows cast at cities hundreds of miles from each other and noticed the different angles cast by the shadows.

5. The Earth’s Circumference Eratosthenes used his surroundings to come up with the the circumference of the Earth. He used the shadows from the obelisk in the center of town and a well, located in the center of a city called Syene, which was to the South. He knew the sun shone directly over this town of Syene on the summer solstice at 12 pm. Then he measured and discovered that the sun's angle of elevation was 1/50th of the earth's circumference. He didn't use the measurement system that we use today, but instead used stades. One stade was equivalent to the length of a stadium. The discovery of the circumference led to the discovery that the earth was not flat.

6. Diagram of His Theory

7. This theory was not verified until 1700 years later when Christopher Columbus sailed West proved this theory true. Eratosthenes’ measurements are within 2% to what we believe as true today.

8. Impact on Society When the Earth was discovered to be round, it had a huge impact on society. Many people were skeptical in the beginning, but now it is a known fact that the Earth is indeed round. With the discovery of a round Earth, there have been many more findings because of it: The ability to make spherical maps has greatly increased allowing us to plot and keep track of the multitude of places discovered and those still left to find. It also helped to increase trade and travel. Once this discovery was made, it was possible to determine many other calculations. The size of the Earth and the distance from the Earth to the moon were able to be calculated. These calculations had the most impact on society and science after the breakthrough of the discovery that the Earth is round.

9. Bibliography Cessna, A. (2009, December 28). Flat earth theory. Retrieved from http://www.universetoday.com/48753/flat-earth-theory/ Hewitt Paul, G. (2009). Conceptual physics. (10 ed., pp. 3-4). San Francisco: Pearson Addison-Wesley. Map projection - mercator. (2003, February 11). Retrieved from http://nationalatlas.gov/articles/mapping/a_projections.htm http://nationalatlas.gov/articles/mapping/a_projections.htm Paul, W. (2011, December 10). How can one prove that the world is round?. Retrieved from http://www.physlink.com/education/askexperts/ae535.cfm Siegel, E. (2011, September 21). Who discovered the earth is round?. Retrieved from http://scienceblogs.com/startswithabang/2011/09/who_discovered _the_earth_ is_ro.phphttp://scienceblogs.com/startswithabang/2011/09/who_discovered _the_earth_ is_ro.php Simanek, D. E. (2006, March). The flat earth. Retrieved from http://www.lhup.edu/~dsimanek/flat/flateart.htm