Earth Was Never Flat!
We know Earth is round because astronauts see it from space. But humans first went into space a little more than 50 years ago. How did people know the Earth was round before that?
How Did they Know the World is Round?
The Ancient Greeks lived millennia before the first telescopes. Their world did not extend far beyond the Mediterranean region. But learned Greeks knew that the Earth was round. Ancient Romans followed their lead. How did they know the world was round? Why did people lose that knowledge and how did they get it back?
Ten Ways to Know
With the link below, learn how people knew the Earth was round. Then answer the following questions.
- Minute Physics, the Top 10 Reasons Why We Know the Earth is Round: http://www.youtube.com/watch?v=o_W280R_Jt8
- The history of the Spherical Earth is described on this Wikipedia page: http://en.wikipedia.org/wiki/Spherical_Earth#Middle_Ages
- List the three reasons that the Ancient Greeks could have known the Earth was round.
- There is one additional reason that the explorers around the time of Magellan could have known that the Earth was round.
- Galileo invented the telescope several decades after Magellan’s voyage. How was the telescope used to determine the shape of the Earth?
- As Europeans spread across the globe, including into the Southern Hemisphere, they made many observations. What are additional reasons that they could have known Earth was round?
- The final reason is more of a thought experiment since no one could travel 30,000 miles without running into water. What could you use as a model to test this reason that Earth is round?