If you have clear skies during Earth Hour, you should experience a lot less light pollution and see more stars than you would on a typical night.
The granddaddy of all constellations, Orion, will be on display in the southwest sky, just under the bright gibbous moon and to the left of planet Venus.
To find Orion - also known as the mythical hunter - look for Orion's "belt" of three bright stars in a row.
Just underneath it is his sword – made of three much fainter stars – and it's challenging to see under urban lighting.
You may also notice a star that's a bit fuzzy. That’s because you are looking at a giant gas cloud that is a nursery for dozens of newborn stars. It's called the Great Orion Nebula – and it is located more than 1,300 light years from Earth.
You should be able to see it with the naked eye – especially during Earth Hour.