A Star, Not a Lamp

The Sun is a main-sequence G-type star roughly 4.6 billion years old. It sits about 150 million kilometers from Earth, inside the Sun's habitable zone - the range where a planet with the right atmosphere can sustain liquid surface water.

Distance matters, but it is not the only dial. Atmosphere, clouds, greenhouse gases, rotation, and geology all help decide whether oceans stay liquid.

Every second the Sun converts roughly 600 million tons of hydrogen into helium through nuclear fusion. That process releases energy equivalent to billions of nuclear bombs. The light you see left the Sun's surface eight minutes ago, but the energy that produced it began its escape from the core.