When the Universe was about 100 million years old, a few different gases began to cluster together in large clouds. The gases were cool enough to allow gravity to draw the particles inwards to form stars, this process is still going on today. As they lose gravitational potential energy the atoms gain kinetic energy thus knocking off the electrons. Now the temperature of this plasma rises and the particles speed up. It forms a glowing protostar, however it is still not a proper star.

Due to the electrostatic repulsion the gases are kept apart. When the temperature reaches about 1,000,000 degrees Celsius they are traveling so fast that they start to fuse together. The fusion releases a huge amount of energy and the star starts to shine.

The early stars were very big. They reached extremely high temperatures and used up their nuclear fuel quickly, this is what causes a star to die, it starts to collapse under gravity. Once again the temperatue will rise and the helium will start to fuse. This fusion will will produce heavier elements (such as oxygen, nitrogen, carbon and magnesium). For each new type of fusion the fuel will be more quickly used up. Once the core has made iron, it beging to use up instead of giving out energy. The core then rapidly shrinks and finally explodes in a huge explosion..a supernova. Through the explosion it scatters all of its material into space. The material then creates elements heavier than iron.

So what happens to stars that are not big enough to go supernova? Well, call back next month and I'll let you know!

For more information about supernovae visit these sites;

http://chandra.harvard.edu/xray_sources/supernovas.html - Chandra X-ray observatory
http://imagine.gsfc.nasa.gov/docs/science/know_l1/supernovae.html - NASA
http://cfa-www.harvard.edu/cfa/oir/Research/supernova.html - Supernova Nexus