In the geocentric model, Venus orbits the Earth and always stays between the Earth and the Sun.
In the heliocentric model, Venus orbits the Sun.
Galileo observed that Venus has phases like the Moon, including a phase in which Venus appears almost fully lit.
Explain why this observation supports the heliocentric model rather than the geocentric model.
When the heliocentric model was first suggested, most people did not accept it.
Give two reasons why.
The heliocentric model was later changed so that the planets move in elliptical orbits instead of circular orbits.
Suggest why scientists changed the model.
80 exam-style questions on Edexcel GCSE Physics 7.1 The Solar System and gravity, covering 7.1.1 Weight and g on different bodies in space, 7.1.2 The Solar System, 7.1.3 Changing ideas about the Solar System, 7.1.4 Orbits of moons, planets, comets and satellites, and 7.1.5 Gravity and orbital motion. Each one has a worked solution and a mark scheme showing where the marks go.