Why does the Sun shine?

The Sun is hot.


FUSION:  4 hydrogen nuclei combine to yield one helium nucleus 

The helium nucleus weighs less than the 4 hydrogen nuclei, and the difference in mass is converted into energy, described by the famous equation:


Note:  A very small amount of m makes a lot of E

The Sun is fusing 600 million tons of hydrogen per second into 596 million tons of helium.

Fission vs. Fusion:

Fusion only can occur if the gas temperature (ie the speed of the atoms) is very,very high -- greater than 10 million degrees Kelvin.

In the Sun, the following chain of events makes the energy which keeps the Sun hot.

ASIDE -- A-bombs vs. H-bombs;  Nuclear Power.

The atom bomb, e.g. the bombs developed by the Manhattan Project and dropped on Nagasake and Hiroshima during World War II:

The H-bomb, or thermonuclear bombs.  

Nuclear Power plants provide 17% of the world's electricity;  as much as 75% of the electricity in France.

 Dirty Bombs, or Neutron Bombs


Countries with Nuclear Weapons:  USA, Russia, United Kingdom, France, China, India, Pakistan, Israel

Countries with active Nucelar Weapons Development Programs:  Iran, Iraq (turned out it wasn't as active as we thought), North Korea