Learning goal 1: Select all of the possible differences between models of the Solar System.The number of planetsThe shape of orbitsThe object at the centre

The Number of Planets: Different models of the solar system can vary in the number of planets they include. For example, the ancient geocentric model, which placed Earth at the center of the solar system, only recognized seven planets. In contrast, the modern heliocentric model recognizes eight planets.

The Shape of Orbits: The shape of the planets' orbits can also differ between models. Early models often depicted the planets' orbits as perfect circles. However, Johannes Kepler's model proposed that the planets move in elliptical orbits. This is now the accepted model in modern astronomy.

The Object at the Centre: Different models can also have different objects at the center of the solar system. The geocentric model, as mentioned earlier, places the Earth at the center. The heliocentric model, proposed by Nicolaus Copernicus, places the Sun at the center. The heliocentric model is the one currently accepted by modern science.