The surface of the Sun is usually around 5800 degrees centigrade, but is a blistering 13.6 million degrees at the core. The core is where the nuclear reactions happen, with hydrogen atoms fusing together to make helium, and this is what powers the Sun and creates all the heat. The outer atmosphere of the Sun, called the chromosphere and which is only visible during a Solar Eclipse, has a temperature of about a million degrees, with occasional heat-waves all the way up to 20 million degrees. Why this thin outer layer should be so much hotter than the rest of the Sun is a bit of a mystery, but we suspect it may have something to do with the intense magnetic fields twisting and reconnecting above the Sun.
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