Astronomy
The History and Future of the Sun's Lifecycle
Quick fact
The Sun has enough hydrogen fuel to keep shining for about 5 billion more years, but it has already burned through half of its core hydrogen.
Why this is interesting
The Sun you see today is middle-aged—halfway through its life. In about 5 billion years, it will swell into a red giant so large that it may engulf Mercury and Venus. What will happen to Earth?