Distant Nature: Astronomy Exercises

Objectives

This exercise will help to demonstrate and verify Kepler's third law. As Kepler did, using Tycho Brahe's data, you will measure the periods (P) of the planets known in Kepler's time, and calculate their semimajor axis (a). You will then compare your calculations to current known values. 

Equipment Materials Needed

Stellarium, scientific calculator.

Subject Introduction

3. The early part of the 17th century was an extremely important time for science, particularly Astronomy. In 1609, Galileo Galilei was the first person to look through the newly invented telescope towards the heavens. His discoveries with this new piece of technology included, sunspots, lunar mountains, and of course, the four largest moons orbiting Jupiter.
   
   At about the same time, Johannes Kepler, using the observational data of Tycho Brahe and their shared belief in the heliocentric model of the solar system, was the first to develop mathematical relationships describing planetary motion. These relationships are now known as Kepler's Laws of Planetary motion. Galileo was able to determine that the four moons he discovered around Jupiter obeyed Kepler's 3^rd Law.
   
   In this exercise, we will look at the naked eye planets and their periods to verify Kepler's 3^rd Law.
   
   Kepler's 3^rd Law can be stated as:

• The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

Equation 1.    

Where P = orbital period in years and a = semi-major axis of orbit in A.U. 

Download Exercise Here: