Active Sun, artwork. The Sun is a huge ball of hydrogen gas, ionised into a plasma by the immense temperatures that are generated by nuclear fusion at its core. This fusion is ignited by the immense pressure generated by the Sun's mass. An active Sun is more likely to eject plasma from its surface, such as the large coronal loop at upper right. The activity varies, peaking roughly every 11 years. The Sun has a diameter of around 1,392,000 kilometres (equivalent to 109 Earths), a mass 330,000 times that of Earth, and a volume 1.3 million times that of Earth. It is 150 million kilometres distant, but its light and heat provide almost all the energy for life on Earth.