How old is the Sun?
Quick Answer
The Sun is approximately 4.603 billion years old — nearly halfway through its main-sequence lifetime. It will continue fusing hydrogen for another ~5 billion years before expanding into a red giant.
The Full Story
The Sun formed approximately 4.603 billion years ago from a collapsing cloud of interstellar hydrogen and helium (a solar nebula). Its age is determined through radiometric dating of meteorites — remnants of the early solar system. The Sun is classified as a G2V yellow dwarf star and is currently about 46% through its main-sequence lifetime. It converts about 600 million tonnes of hydrogen into helium every second through nuclear fusion, generating 3.8 × 10²⁶ watts of power. In approximately 5 billion years, it will exhaust its hydrogen fuel, expand into a red giant (engulfing Mercury, Venus, and possibly Earth), then shed its outer layers to form a planetary nebula. The remaining core will become a white dwarf about the size of Earth, slowly cooling over trillions of years.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The Sun is Dying — What Happens When Our Star Runs Out of Fuel"