Animation for AST210H: Kepler's Laws

This is an interactive java animation which allows the students to experiment the planet motion under Kepler's law. You can change the value of the semi-major axis "a" and the eccentricity "e" by clicking on the corresponding number buttons and then press "start". The unit of "a" is in AU which is the distance between the earth and the Sun.

The clock shows the time passed in the unit of earth-year. You can measure the periods of the planet for different "a" (Kepler's third law). The button "sweep" let you see the area swept out by the planet (only work for a = 3). Use the clock to experiment the area swept out by the planet at equal time.

The button "clear" will clear the whole image and reset the clock to 0.0.

The default setting is a = 3 AU , e = 0.6 , and the sweeping time interval is 0.4 earth year.

This animation was created by Ming Zhu . Send questions or comments to :