A star is an extremely hot sphere of gas that emits light.

A light-year is the distance light travels in one year.

1 billion = 1 000 000 000 (one thousand million).

A galaxy is a group of billions of stars.

The name for the whole of space and everything in it is the universe.

Stars, galaxies and the universe

Science

In the Gravity in space unit, they will build on this knowledge to learn to how gravitational forces cause orbital motion and about stellar evolution and cosmology, including red-shift and the big bang. 

In primary science, pupils learnt about the cause of day and night, the movement of the Earth orbiting the Sun and the Moon orbiting the Earth, and about stars and planets we can see in the night sky.

Our solar system and beyond

The Sun is a much bigger and brighter star than all other stars.

The Sun is much closer to Earth than all other stars.

The Sun is a different colour to all other stars.

Why do the stars in the night sky look different to the Sun, which is also a star?

a star and the objects (e.g. planets) in orbit around that star

a huge sphere of gas that gives out light

Match each keyword to the correct definition.

the time taken for light to travel one year

the distance it would take to travel to the nearest star

Starting with the smallest, put these in order of size from smallest to largest.

Stars orbit the Sun at very great distances.

Stars are hot and bright because of reactions happening within them.

Within a galaxy, stars are light years apart.

Select the statements about stars that are true.

What is a constellation in the night sky?

How many planet Earths could you fit into the Sun?

How long does it take for light from the Sun to reach Earth?

Exit Quiz