What is the Sun?
The Sun is our reliable source of light and heat – and therefore energy. It’s also a violent world of nuclear fusion, turbulent gases, twisted magnetic fields and explosive outbursts.
At 1.4 million kilometres across, the Sun is by far the largest body in the Solar System. Like any other star, it is a huge sphere of glowing gas, mainly hydrogen and helium. Nuclear fusion in the Sun’s 15-million-degree core generates the light and heat emitted from its 5500°C surface. The Sun’s rotation period is about 27 days as seen from the Earth, but the equatorial parts rotate faster than the polar regions. As a result, magnetic fields get twisted, leading to dark sunspots, bright flares, huge prominences and massive ejections of gas. Despite all this violence, the Sun has sustained life on Earth for over 3 billion years.
The Sun is a star. Like most other stars, it has cooler, dark spots on its surface, as well as giant explosions. Luckily, the Earth is at a safe distance — 150 million kilometres!