THE SUN

The Sun is a G-type main-sequence star — a massive ball of plasma held together by its own gravity and powered by nuclear fusion in its core. It contains 99.86% of all the mass in the Solar System and its gravity keeps every planet, asteroid, and comet in orbit around it.

At its core, the Sun fuses 600 million tonnes of hydrogen into helium every second. The energy takes up to 100,000 years to travel from the core to the surface — then just 8 minutes 20 seconds to reach Earth. The Sun is ~4.6 billion years old with roughly 5 billion years of fuel remaining.