How old is the Sun?
The Sun is about 4.6 billion years old. Scientists know this from the age of the oldest meteorites, which formed at the same time as the solar system.
The Sun formed from a huge cloud of gas and dust that collapsed under its own gravity. Most of the material gathered in the center and became hot and dense enough to start nuclear fusion. The leftover disk around it formed the planets, moons, asteroids and comets.
Scientists date the solar system using radioactive elements in meteorites. The oldest solid grains, found in meteorites such as Allende, are about 4.57 billion years old. Models of how stars like the Sun age agree with this figure.
The Sun's future
The Sun is about halfway through its life as a stable star. In about 5 billion years, it will run low on hydrogen in its core and swell into a red giant, probably swallowing Mercury and Venus. Later it will shed its outer layers and become a small, dim white dwarf.
Did You Know?
The Sun is a fairly average star called a yellow dwarf. Many stars in the Milky Way are smaller, cooler red dwarfs.