Stars Direct

: Stars form within cold, dense clouds of gas and dust known as molecular clouds or stellar nurseries. Gravity causes these clouds to collapse into hot, spinning "protostars".

Every star undergoes a distinct life cycle that can last from a few million to trillions of years, depending on its initial mass. : Stars form within cold, dense clouds of

Stars are massive, luminous spheres of plasma held together by their own gravity, primarily composed of hydrogen and helium. They are the fundamental building blocks of galaxies and serve as the universe's primary energy producers through nuclear fusion in their cores. While the Sun is the nearest and most well-studied star to Earth, astronomers estimate there are up to one septillion stars in the observable universe. Life Cycle of a Star Stars are massive, luminous spheres of plasma held

Astronomers categorize stars based on their spectral characteristics , which correspond to their surface temperatures. Star Basics - NASA Science Life Cycle of a Star Astronomers categorize stars