Orbital Motion, Natural & Artificial Satellites [Physics only]

Gravity and orbits

• Gravity provides the force that allows planets and satellites (both natural and artificial) to maintain their circular orbits
• The gravitational force acts towards the centre of the orbit: the Earth pulls the Moon towards the Earth; the Sun pulls the planets towards the Sun
• Planets orbit the Sun. Moons (natural satellites) orbit planets. Artificial satellites, built and launched by people, orbit the Earth (or other bodies) for communications, weather observation, navigation and astronomy
• Similarities: all are held in orbit by gravity and all follow roughly circular paths. Differences: planets orbit a star; moons and artificial satellites orbit a planet; artificial satellites are made by people and are far smaller