The Evolving Universe

Smithsonian Institution

Our Galaxy: A Star is Born

View/Download Poster (PDF)

Large clouds of dust and gas—called nebulae—lurk between the stars throughout our galaxy. Stars and planets form when the material in these clouds compresses and clumps together.

It takes a few million years for enough dust and gas to crowd together, heat up, and begin revolving in a swirling mass. The center grows denser and denser until there is enough hydrogen and helium to trigger nuclear fusion, and a star is born.