The main features of the solar system
Our home, planet Earth, is part of a system of bodies that orbit a central star – the Sun. This solar system consists of four inner rocky planets and four outer gas giant planets as well as an asteroid belt, containing thousands of huge rocks, dwarf planets and comets.
Our solar system contains a central star with eight planets, dwarf planets, moons, comets and asteroids.
- The Sun is our nearest A large mass at the centre of a Solar System (if there are other bodies present) that produces heat and light, eg the star at the centre of our Solar System is called the Sun..
- The planets The full path that a planet travels around, eg Earth takes 365 days to complete one orbit of the sun. the Sun.
- The time taken to orbit the Sun increases with distance from the Sun.
- The force of attraction between all objects. The more mass an object has, the larger the force of gravity it exerts. keeps the planets in orbit around the Sun and the moons in orbit around their planets.
- From the Sun, the order of the planets is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. You might need to be able to recall this in the exam.
- The Large objects in orbit around a star, but excluding comets and asteroids. go around the Sun in slightly squashed circular An orbit that is the shape of an ellipse. An ellipse is similar to a slightly stretched circle..
- Pluto is classified as a A planetoid that is too small to be considered to be a planet, eg Pluto. or planetoid. It has a highly elliptical or An orbit that is highly elliptical, ie the orbit is a narrow ellipse shape..
Moons
Most of the planets and some of the dwarf planets have bodies that orbit them. These natural Body that orbits a planet. For example, the Moon is a natural satellite of the Earth but communication satellites are artificial satellites of the Earth. are called moons.
Question
Which two planets have no moons?
Mercury and Venus.