Objects in Space (Edexcel IGCSE Physics: Double Science)

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

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