Which type of solar system model is illustrated in the diagram?

The correct answer is: a heliocentric model.

In a heliocentric model, the Sun is at the center of the solar system, with the planets, including Earth, orbiting around it. This model was proposed by Copernicus and is widely accepted in modern astronomy, contrasting with the geocentric model, which places the Earth at the center. If you have more detailed questions about these models, feel free to ask!