Part 1

1. What must be your location if the stars move across the sky in circle centered directly overhead?

2. What is the basic difference between the Ptolemaic and Copernican models? Why the Ptolemaic model is considered incorrect?

3. Ancient astronomers were troubled by variations in the brightness of the various planets with time. Does the Ptolemaic or the Copernican model account better for these variations?

4. The earth takes almost exactly 24h to make a complete turn on its axis, so we might expect each high tide to occur 12 h after the one before. However, the actual time between high tides is 12 h 25 min. Can you account for the difference?

Part 2

Conduct the following experiments.

- While riding in a car, train, bus, or any vehicle that allows you to move along at a steady rate but allows you to have your mind, hands, and eyes free to concentrate, take a small object, toss it straight up (avoid hitting the ceiling), and watch it fall. You can even just walk along and toss something up, but make sure you have lots of room to keep walking without looking where you are going. What kind of path does the object follow? Does it come back to where it left your hand?

- Using something you can spin in a circle by hand (a frisbee lying on its back works well or a paper plate), place a small object (like a key or a paper clip) on it, and spin it. Does the object stay on or fly off? Can you make it fly off, and if so, how do you do it?
All questions are separate answer.

Part 3

Read the following two arguments against the Copernican system.

- The first part of the argument questions "Why don't we see things left behind by the Earth as it spins and travels around the sun?" For example, why does a ball dropped from the top of a high tower fall to the base of the tower instead of being left behind by the spinning Earth to finally hit the ground some place far away?

- The second part of the argument asks "Why don't things get thrown off by the spinning Earth in the way we see other things thrown from spinning objects, such as water flying from a car tire after it rolls through a puddle?"