When you look at the sky on a clear night, it's a spectacular sight.
You can see stars, the Moon, maybe even planets but can you see a great bear, a hunter or a scorpion?
Ancient civilizations believed that they could see patterns formed by stars.
They called them constellations.
Constellation - Latin for 'group of stars'
These imaginary patterns had real purpose.
Different ones are visible at different times in the year and from different places on Earth.
Knowing this let people navigate by the stars.
For example, in the northern hemisphere the constellation Ursa Major is always visible.
Ursa Major - The Great Bear
Within this is a collection of stars known by various names.
The Big Dipper
By identifying the last two stars and drawing an imaginary line upwards, you find Polaris.
Polaris - The North Star
As the Earth rotates, the stars appear to rise and set in the night sky.
They appear to rotate around Polaris.
This is because it is almost exactly above the North Pole - meaning that if you can find it in the night sky, you know which direction is north.
In modern astronomy, the term "constellations" has been given new meaning, defining regions of space.
The sky is divided into 88 constellations.
Every single star is now said to belong to one of these regions.
So the next time you look up at the night sky, see what patterns you can find.