Nuclear energy is released during fission and fusion.

WSJ: The New Nuclear Revolution

The good news is that the big names in nuclear energy -- like Areva, Hitachi, General Electric and Toshiba -- have recently been joined by a bevy of high-tech start-ups seeking to develop advanced nuclear-reactor designs for both fission and fusion energy production.

WSJ: The New Nuclear Revolution

Acting alone, gravity would cause stars to collapse completely, but as long as energy is produced at their centers by nuclear fusion (the joining of atomic nuclei to form new elements, as in a hydrogen bomb), the star is heated and puffed up.

CNN: Why gamma-ray burst shocked scientists

Stars shine by nuclear fusion the merging of light atomic nuclei to release energy.

ECONOMIST: Sir Fred Hoyle

When this beam struck a target of erbium deuteride, the team detected neutrons coming from the target with precisely the energy expected if they were generated by the nuclear fusion of two deuterium nuclei.

BBC: NEWS | Science/Nature | Table-top fusion 'demonstrated'

On earth, a magnetically confined plasma is what nuclear-fusion researchers wrestle with in their search for a clean source of energy.

ECONOMIST: Hot stuff

However, while mining helium-3 from the moon will be one challenge, extracting energy from it is another, as it relies on nuclear fusion, rather than fission used in today's nuclear reactors.

CNN: Mining the moon for a nuclear future

This project, a collaboration between America, Russia, Japan and Europe, is intended to create sustained nuclear fusion by squeezing gases so hard that their atomic nuclei fuse together and give off more energy than was needed to squeeze them.

ECONOMIST: The diamonds in the rubble