Use the electric orrery to view orbits of the planets in our Solar System.
An ellipse has 2 focus points or foci. At any point in its orbit, a planet's total distance from these 2 focus points stays the same. An ellipse also has 2 lines of symmetry. The longer line is the major axis. The shorter line is the minor axis. Half of the major axis is the semi-major axis. Likewise, half of the minor axis is the semi-minor axis.
Johannes Kepler wrote 3 laws to describe the motions of planets. This useful video from the European Space Agency describes Kepler's 3 Laws. You can investigate this science using our Kepler's Laws workshop.