Our Sun is a steady and everlasting companion. Reliable like a clock, its apparent passage across the sky allows us to measure time. The Sun and its path is also the source of Earth’s seasons. But in many respects, our Sun is far from calm and unchanging.
Close up, the Sun shows extensive variation and activity. Bright explosions called flares regularly cause huge outbreaks of radiation. Darker, cooler areas called sunspots emerge, move, change shape and vanish. The Sun also releases material into space in powerful eruptions, called solar particle events.
