Supernovae are powerful and bright explosions that occur at the end of the life of certain types of stars. These events are among the brightest and most energetic phenomena in the Universe and can temporarily exceed the luminosity of entire galaxies.

There are several types of supernovae, the best known of which are:

1. Type I supernovae: These explosions occur in binary systems where one star is a white dwarf. When the white dwarf accumulates enough mass from its partner (usually a red giant), it can reach the Chandrasekar limit (about 1.4 solar masses). When this limit is reached, a thermonuclear reaction begins, leading to an explosion.

2. Type II supernovae: These explosions result from the collapse of the core of a massive star (usually greater than 8 solar masses) when it exhausts its nuclear fuel. The core of the star is compressed by gravity and the outer layers of the star are ejected into space, creating a bright burst of light.