Can burn oxygen in space

Science in dialogue

Why does the sun burn in space without oxygen and what was it caused by?

The sun generates light and heat, but it does not burn - and therefore does not need oxygen to generate energy. From a chemical point of view, burning is a process in which oxygen enters into a chemical reaction with other substances. Probably the most spectacular form of combustion is fire, when wood, paper or other materials react with the oxygen in the air. Bonds between atoms are broken, new bonds are formed. If the energy that is required for the bonds of the end products is less than the energy that was contained in the bonds of the starting materials, then the "excess" energy is released as light and heat. However, the atoms themselves remain unchanged.

Different on the sun. There, energy is not released through combustion, but through what scientists call nuclear fusion - individual atomic nuclei fuse and a completely different type of atom is created.

The sun is a huge, hot ball of gas - more than 100 times larger and around 333,000 times heavier than the earth. It consists mainly of hydrogen and helium, the smallest and lightest atoms.

Associated with the Sun's vast mass is a very large force of gravity (known on Earth as the force that makes everything fall down). It ensures that the particles in the center of the sun are squeezed extremely tightly together. As a result, the temperature rises sharply (similar to how the compressed air warms up when a bicycle tube is inflated). The high temperature (around 15 million Kelvin in the center of the sun) and the high density make it possible for the positively charged atomic nuclei to overcome their repulsion and fuse. In the sun, hydrogen atoms fuse in a multi-stage process to form a new atom - a helium atom. It is lighter than the hydrogen atoms that made it. The “missing” mass is converted into huge amounts of energy according to the formula E = mc² found by Albert Einstein. We can perceive this as warmth and light on the earth, which is around 150 million kilometers away.

This process began around 4.6 billion years ago. At that time, the sun emerged from a huge gas cloud. External disturbances caused gas pressure and gravity to become unbalanced. Gravity prevailed, the cloud collapsed. Due to the increasing force of gravity, the gas cloud was then compressed more and more until the density and temperature were high enough that a nuclear fusion could ignite. Today the sun is a stable star on which gas pressure and gravity are in balance.

The question was answered by Professor Dr. Manfred Schüssler, Max Planck Institute for Solar System Research