The Earth and the Solar System

Learning objectives

Explain day and night and the apparent daily motion of the Sun and stars from the Earth rotating on its tilted axis once in about 24 hours, and know that the Earth orbits the Sun once in about 365 days

Explain the monthly cycle of the phases of the Moon from its orbit around the Earth

Describe the Solar System as the Sun, eight planets, dwarf planets, moons, asteroids and comets (at Extended, moving in elliptical orbits), know that it formed by accretion from a cloud of gas and dust, and that light from the Sun takes about 500 s to reach the Earth

Know that the Sun's gravitational attraction keeps the planets in orbit and that the Sun contains most of the mass of the Solar System, and at Extended explain why orbital speed decreases with distance from the Sun and why orbits are elliptical

Calculate average orbital speed using v = 2πr/T, and analyse tables of planetary data such as orbital distance, orbital period, density, surface temperature and gravitational field strength (Extended)

Know that the gravitational field strength at the surface of a planet depends on the mass of the planet, and that the field around a planet becomes weaker as the distance from the planet increases