Kepler's Laws: Find the Mass of the Sun

Many years ago, a mathematician named Johannes Kepler created a set of rules explaining planets' movement in our Solar System. Thanks to later discoveries about gravity by Isaac Newton, we can now apply Kepler's Laws to determine properties of our Solar System, such as the mass of the Sun.

Use this activity to discover more about Kepler's 3 Laws of planetary motion and calculate the mass of the biggest object in our Solar System, the Sun.

By the end of this activity you will:

  • Know the fundamental principles of Kepler’s Laws.
  • Know the properties of an ellipse.
  • Be able to use Kepler’s 3rd Law to find the mass of the Sun.

To complete this resource you will need: 

IT Equipment

  • OPTIONAL - Spreadsheet software (e.g. MS Excel) - if you are new to spreadsheet software, use this MS Help Sheet
The picture shows a cartoon portrait of Johannes Kepler in front of an artist's impression of the Solar System.
Credit The Schools' Observatory