One, two, three generations of stars
The first stars formed from the hydrogen and helium that originated in the Big Bang 13.8 billion years ago. When they burned out, the next stars formed from their remains. Astronomers divide stars into three generations.
Huge stars lit up the universe
1 The first stars originated a few hundred million years after the Big Bang, when big clouds of hydrogen and helium collapsed inward. These stars were 100+ times heavier than our Sun, but quickly burned out and so have never been observed directly.
Stars rose from the dead
2 The next generation of stars originated from the remains of the first ones. The oldest of these are red dwarfs, which still exist at the centre of the Milky Way and in star clusters orbiting our galaxy. They are typically 11-13 billion years old.
New stars are still being born
3 Today the Milky Way consists mainly of more recent stars such as the Sun, which is less than five billion years old. New stars still
