The Geocentric Universe

Lesson Plan - Get It!

Audio:

Imagine that you live in a world where no one ever flew to the moon, where there are no airplanes, no satellites, not even any telescopes.

As far as you know and can tell, the earth is standing perfectly still except for the occasional rumblings of earthquakes.

• If you live in that kind of world and look out at the night sky, what would you imagine to be happening?

That is exactly the way it was for people living in the ancient world. The philosophers of Ancient Greece began to make observations of the night skies and developed the best models of the universe they could. As time went on, though, it became apparent that their theories and models were not exactly accurate.

Take a look at the following video. It shows two models of the universe. The first is known as the Ptolemaic model of the universe. The second model is known as the Copernican model.

As you watch, write down notes on the various celestial bodies represented in the video and the differences and similarities you notice between the two models. (Note: The Ptolemaic model comes first, followed by the Copernican model at 24 seconds. There is no sound in the video.)

Watch this Ptolemaic vs. Copernican Model video, by Grander Meador, then share your observations with your parent or teacher:

Reflect on the following questions and discuss:

• Which one would best be described as geocentric, or "earth-centered," and why?
• Which would best be described as heliocentric, or "sun-centered," and why?
• Why was the Ptolemaic model perfectly reasonable during its time?

You have made your own observations about these two important historical models of the universe.

In the Got It? section, you will delve more deeply into the development of astronomy and some of the major figures and ideas that altered our understanding of the universe in which we live.