Nuclear fusion is an atomic reaction that fuels stars. In fusion, many nuclei combine together to make a larger one (which is a different element). The result of this process is the release of a lot of energy (the resultant nucleus is smaller in mass than the sum of the ones that made it; the difference in mass is converted into energy by the equation E=mc2). A constellation is a group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure. A supernova is an explosion of a massive supergiant star that gives of the engery of 1044 joules, as much as the total output of the sun during its 10 billion year lifetime. Type I if their light curves exhibit sharp maxima and then die away gradually. Type II supernovae have less sharp peaks at maxima and peak at about 1 billion solar luminosities.