Watching the night sky can bring a sense of peace and calm to a troubled soul, but beyond the vision of naked human eyes lies a universe bustling with activity. One particular violent source of bustle – and indeed a cosmic engine that drives the evolution of new stars and planets – is the supernova. A supernova happens when a particularly massive star has exhausted fuel to fuse and blows up.
A star is a delicate balance between two forces: the outward energy and pressure created by nuclear fusion and the implosive tug of gravity, the result of the star’s large mass.
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When a star can no longer fuse the nuclei of an element and release more energy than required to fuse them, gravity starts to gain the upper hand. The star will soon collapse in a brief amount of time, causing its outer shells to explode. This is a core-collapse supernova.
Another type of supernova occurs when two stars – one or both of which are white dwarfs – orbiting each other collide or one of the white dwarfs absorbs enough matter from the other star. Either way, the result is a thermal runaway supernova.
A supernova expels large amounts of energy, radiation, and elements into the space around it. The heavy metals found in earth’s crust – including the gold that we prize and the uranium that we use in nuclear reactors – were first created in the crucible of some supernova aeons ago.
