The Sun is the beating heart of our solar system — a colossal sphere of superheated plasma held together by its own immense gravity. At its core, temperatures exceed 15 million °C, where nuclear fusion fuses hydrogen nuclei into helium, releasing the energy that has lit our sky for 4.6 billion years. That energy takes around 100,000 years to travel from the core to the surface, then just 8 minutes to reach Earth.

The Sun is currently halfway through its life. In roughly 5 billion years it will expand into a red giant, engulfing the inner planets, before shedding its outer layers as a planetary nebula and leaving behind a cooling white dwarf. For now, its solar wind — a constant stream of charged particles — fills the entire solar system, shaping planetary magnetospheres and painting auroras on worlds billions of kilometres away.