BIRTH

After the Big Bang, it took 300,000 years for stable hydrogen and helium atoms to form. Gradually these atoms began to clump together into gas clouds called nebulae.

Over the course of the next 300 million years, these clouds grew. They attracted more and more atoms and so became increasingly dense and hot.

Read about the evolution of the Universe

Nuclear explosions

Eventually, the centres of these clouds became so hot and dense that they exploded in huge nuclear reactions. Hydrogen atoms began to fuse together and the clouds were transformed into blazing balls of fire. The first stars were born.

Stellar birth is still going on today. As you read this, stars are emerging and dying all over the Universe, individual episodes in an huge process of cosmic recycling.

Find out how a star dies

Our Sun

Even our own parent star, the Sun, is part of this cycle. The Sun wasn't one of the original stars in the Universe, it was born about 10 billion years after the Big Bang. There are atoms inside the Sun that were blasted out by stars long since dead.

Explore the Sun with our travel guide to the Solar System

During their lives, stars act as enormous atomic factories. In fact, most of the atoms in your own body were generated inside stellar furnaces in a process called nucleosynthesis.

What happens inside a star during its lifetime?