If there is no oxygen in space, how does the sun burn?

Since ancient times, the sun has been an object of magic. Images that capture its constant brightness and overflowing energy, reminiscent of a fireball, have led many people, from ancient astronomers to the digital-age curious, to wonder: How could the Sun “burn” if there was no oxygen in space?

Contrary to what many people think, a star does not burn like a fire here on Earth. For there to be fire, free atmospheric oxygen is needed, an element that is abundant on our planet, making up 21% of the atmosphere. In contrast, space, known for its almost absolute vacuum, contains trace amounts of oxygen, insufficient for any kind of combustion, as explained by the European Space Agency (ESA).

Burning on our planet

For example, we can use the process of a piece of paper, which, when set on fire with a match, causes the carbon, hydrogen and oxygen-rich atoms of the paper to react with atmospheric oxygen. This encounter produces carbon dioxide and water, releasing energy in the form of heat and light. This process is known as combustion.