Use an Internet search engine (such as Google, Alta Vista, Yahoo, etc.) to find information on the orbital period and average distance from the Sun of each planet. Create a table showing these values for each planet.

Next, use an Internet search engine to find the equation for the circumference of a circle.

Assuming each planet's orbit is approximately circular, calculate the average orbital velocity of each planet around the Sun in both kilometers per hour and miles per hour.

1. Which planet is moving fastest around the Sun?

2. Which planet is moving slowest around the Sun?

3. Is there any systematic relation of a planet's orbital velocity and its distance from the Sun?

4. What surprises you most about the numbers you calculated?

Now, use an Internet search engine to find the approximate equation for the circumference of an ellipse. Also use the search engine to locate information on the orbital period and orbital dimensions of Halley's comet about the Sun.

1. What is the average orbital velocity of Halley's comet about the Sun?

2. How does this compare to the average orbital velocities of the planets?