Supernova

In large size stars, nuclear fusion will continue until iron is formed. In stars, iron acts like an energy sponge. It soaks up the star's energy. This energy is eventually released in a big explosion called a supernova.

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One night in 1572, Danish astronomer Tycho Brahe saw what he thought was a brilliant new star in the constellation Cassiopeia. (We now know he was observing a supernova.) In 1604, a second supernova was observed. These discoveries caused scientists to seriously question Ptolemy's theory that all stars were contained in an outermost sphere of the universe that never changed.

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When a massive star dies, it runs out of fuel, collapses under its own weight and explodes as a supernova.

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Roman will use multiple methods to investigate dark energy. One involves surveying the sky for a special type of exploding star, called a type Ia supernova.

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