The Solar System (Cambridge International IGCSE Science)

The Solar System

• The Solar System consists of:

  • the Sun
  • eight planets
  • natural and artificial satellites
  • minor planets, including dwarf planets

The Solar System

The Solar System consists of one star (the Sun) and the objects that orbit it, including the planets, moons, dwarf planets, asteroids and comets

The Sun

• The Sun is the closest star to the Earth
• It is found at the centre of the Solar System

The planets

• There are eight planets which orbit the Sun

• In ascending order of the distance from the Sun, these are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

• The planets can be divided into two groups

  • the inner rocky planets
  • the outer gas giants

Dwarf planets

• A dwarf planet is an object similar to a planet, but much smaller
• The gravitational field around a planet is strong enough to pull in nearby objects (with the exception of natural satellites)
• Whereas, the gravitational field around a dwarf planet is not strong enough to pull in nearby objects

Satellites

• There are two types of satellites: natural and artificial

Natural and artificial satellites of Earth

The Moon is a natural satellite of the Earth. Many artificial satellites orbit around the Earth.

• Natural satellites are objects that orbit planets
• A moon is a type of natural satellite
• Artificial satellites are manmade objects that orbit another object in space
• The International Space Station (ISS) is an example of an artificial satellite that orbits the Earth

Orbiting bodies

• The Solar System is made up of many bodies which orbit around other bodies

• Smaller bodies orbit around larger bodies

  • For example, planets orbit the Sun and moons orbit planets

• The orbiting bodies in the Solar System are shown in the table below:

Table of orbiting bodies in the Solar System

Exam Hint You need to know the order of the 8 planets in the Solar System. The following mnemonic gives the first letter of each of the planets to help you recall them:

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Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune