Sun

The star at the centre of our Solar System. It is the most important source of energy for life on Earth.

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The Sun is the star at the centre of the Solar System. It is a nearly perfect ball of hot plasma. It shines because of nuclear fusion reactions in its core. The Sun radiates this energy mainly as visible, ultraviolet, and infrared light, and is the most important source of energy for life on Earth.

This image shows the bright light of a solar flare on the left side of the Sun and an eruption of hot ionised gas, called plasma, shooting through the Sun's atmosphere, called a prominence eruption. NASA/SDO