Nuclear Fusion

The Sun - our own nuclear power station

© NASA

This happens when two light atoms are made to stick together to form a heavier one. A lot of energy is then produced. All chemical elements in the Universe heavier than Hydrogen and Helium were created in stars through nuclear fusion.

At the end of the star's lifetime, these heavy elements can be re-distributed to nearby clouds or nebula, and will form the building blocks for future generations of stars.

Nuclear power stations on earth work by spliting heavy atoms into two lighter ones. This is called nuclear fission.

Scientists are trying to find a way to make nuclear fusion power stations, since they would be much cleaner to run and produce a lot of energy. However, this is very difficult because you have to make the "fuel" very hot and squeeze it down into a tiny space to get fusion to work.

This happens in the inside of a star because of gravity crushing everything down, but it is much harder inside a building on Earth!