Where stars are born

A cloud of gas and dust

Huge clouds of gas and dust drift through space. Most of the gas is hydrogen, the lightest element. These clouds are very cold, and so big that light takes tens of years to cross one. Stars are born inside clouds like this.

Why?Any spot in the cloud that is a little denser has slightly stronger gravity, so it pulls in the gas around it. The more it pulls in, the heavier it gets, and the harder it pulls.

Learn moreA cloud like this is called a nebula. The Orion Nebula, in the constellation Orion, is a star nursery you can faintly see with your own eyes. The colors and sizes on screen are a rough sketch.

When

Before birth

Star we are watching

Cloud of gas and dust

Size · state

Tens of light-years across · mostly hydrogen