Image of a swirling galaxy of stars and planets

RF Dreamstime

In 1929, Edwin Hubble surveyed many galaxies and discovered graphically that the speed they move away from us is proportional to their distance from us. This revolutionised our view of the development and age of the universe, and led to the concept of the Big Bang.


This unit provides opportunities for your students to learn about the way the universe expands, and how this leads to more distant galaxies moving away from us faster.

What is Hubble's law?

Edwin Hubble - an American astronomer - first plotted a graph in 1929 to show that the universe is expanding. This tells us that the universe started from a single point and expanded outwards to the size we see today. The graph allows us to calculate how old the universe is. He developed Hubble’s Law: speed = Hubble constant x distance.

What is Hubble's telescope?

The Hubble Space Telescope was launched in 1990 and orbits the Earth. Its position above the atmosphere gives it an amazing view of the universe from where it sends back spectacular pictures of stars, galaxies and nebulas. 


  • To understand how the expansion of the universe leads to increasing galaxy speed at greater distance, and the illusion of Earth being at the centre of the universe.
  • Practise simple measurement and scale conversions.
  • Practise speed calculations.
  • Learn some technical terms in space science and develop transferable skills.
  • Draw graphs of galactic speeds versus distance.
  • Use their graphs to calculate the age of the universe.

Age range:


Curriculum links:

Science – Physics, Cosmology, Maths, Art and Design

Preparation needed:

You will need:

• Rubber bands of different lengths.

• Metal washers of different sizes, pins and board or thick card.

• Small coloured stickers to identify the galaxies.

• Rulers, pencils, and tape measures.

• Graph paper.

• Access to the internet.

You will need to:

• Photocopy the table – at least one per group.