Objects in Space (Edexcel IGCSE Physics)

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Planets, stars & galaxies

The Universe

  • The Universe is defined as

    A large collection of billions of galaxies

  • It is also the name given to the entirety of space

Galaxies

  • A galaxy is defined as

    A large collection of billions of stars

  • Stars are large astronomical objects such as the Sun

The Solar System

  • Stars may be a part of a planetary system

    • In a planetary system, planets and other astronomical objects orbit around a star at the centre

  • Our Solar System is in the Milky Way galaxy

  • The Sun is at the centre of our Solar System

  • Our planet, the Earth, is the third of eight planets in our Solar System

Hierarchy of the Solar System

Diagram illustrating the universe, Milky Way Galaxy, and our solar system with labelled planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

The Universe is a large collection of galaxies and a galaxy is a large collection of stars. The Sun is a star at the centre of our Solar System in the Milky Way galaxy

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Ashika

Author: Ashika

Expertise: Physics Project Lead

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.