The Solar System

1 Describe the Solar System as containing:

(a) one star, the Sun

(b) the eight named planets and know their order from the Sun

(c) minor planets that orbit the Sun, including dwarf planets such as Pluto and asteroids in the asteroid belt

(d) moons, that orbit the planets

(e) smaller Solar System bodies, including comets and natural satellites

2 Know that, in comparison to each other, the four planets nearest the Sun are rocky and small and the four planets furthest from the Sun are gaseous and large, and explain this difference by referring to an accretion model for Solar System formation, to include:

(a) the model’s dependence on gravity

(b) the presence of many elements in interstellar clouds of gas and dust

(c) the rotation of material in the cloud and the formation of an accretion disc

3 Know that the strength of the gravitational field

(a) at the surface of a planet depends on the mass of the planet

(b) around a planet decreases as the distance from the planet increases

4 Calculate the time it takes light to travel a significant distance such as between objects in the Solar System

5 Know that the Sun contains most of the mass of the Solar System and this explains why the planets orbit the Sun

6 Know that the force that keeps an object in orbit around the Sun is the gravitational attraction of the Sun