supernova

American  

[soo-per-noh-vuh] / ˌsu pərˈnoʊ və /

noun

Astronomy.

plural

supernovas, supernovae

1. the explosion of a star, possibly caused by gravitational collapse, during which the star's luminosity increases by as much as 20 magnitudes and most of the star's mass is blown away at very high velocity, sometimes leaving behind an extremely dense core.

2. the star undergoing such an explosion.

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supernova British  

/ ˌsuːpəˈnəʊvə /

noun

1. a star that explodes catastrophically owing to either instabilities following the exhaustion of its nuclear fuel or gravitational collapse following the accretion of matter from an orbiting companion star, becoming for a few days up to one hundred million times brighter than the sun. The expanding shell of debris (the supernova remnant ) creates a nebula that radiates radio waves, X-rays, and light, for hundreds or thousands of years Compare nova

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supernova Scientific  

/ so̅o̅′pər-nō′və /

plural

supernovae

1. A massive star that undergoes a sudden, extreme increase in brightness across the electromagnetic spectrum, followed by a more gradual decrease lasting from several days to several months. Supernovae occur when a supergiant star collapses suddenly at the end of its life, condensing its core material into an extremely compact mass that then undergoes a slight rebound. The resulting shock wave sends all matter surrounding the core flying into space, leaving a neutron star or black hole at the site of the core's collapse. Supernovae may also occur when a white dwarf accretes material from a companion red giant star, resulting in an increase in mass that eventually triggers carbon fusion in the core of the white dwarf; the sudden increase in available fuel causes energy to be released in a violent explosion. In both cases the shock waves induce further fusion in the matter surrounding the collapsed core; the many elements resulting from this fusion and from the various other stages of nucleosynthesis over the lifetime of the star are scattered into space. These elements serve as the material from which new stellar and planetary systems are formed; in fact, every heavy element found on Earth is thought to have been the product of supernovae explosions. The last supernova to be observed in the Milky Way was seen in 1604 by Johannes Kepler and was used by Galileo, at his trial, as evidence against the presupposition that the universe never changes.

2. Compare nova

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supernova Cultural  

1. A large star in its death throes that suddenly explodes, increasing many thousands of times in brightness.

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Discover More

In 1987, a supernova was sighted near the Milky Way galaxy. This supernova provided astronomers with a unique opportunity to test the theories of the structure of stars.

Most heavy elements are created by nuclear reactions in supernovas and then returned to space.

Etymology

Origin of supernova

First recorded in 1925–30; super- + nova

Explanation

Supernova is an astronomical term for a star that explodes like crazy. When a star turns into a supernova, it becomes extremely bright. Supernova sounds like a superhero, but it refers to the super explosion of a star. A nova is also the explosion of a star, but a supernova has more energy. A supernova happens when a star becomes bright, bursts, and its matter is scattered in all directions, with light and radiation shooting out. Some say our sun will turn into a supernova someday, which would destroy all life on Earth. Don’t worry, that’s a long way off.

Example Sentences

Then there’s poet and novelist Ocean Vuong, whose appearance on the show in 2025 was like a supernova.

From Los Angeles Times • May 18, 2026

Researchers are especially interested in the powerful "kicks" neutron stars receive during supernova explosions.

From Science Daily • May 15, 2026

Scientists believe they are created by some of the universe's most violent events, including supernova explosions, jets from black holes, and pulsars.

From Science Daily • May 14, 2026

These features are typical of a supernova, specifically a "stripped-envelope core-collapse" supernova, not a kilonova.

From Science Daily • Apr. 24, 2026

The core implodes violently, the exterior rebounds and a supernova explosion results.

From "Cosmos" by Carl Sagan

Related Words

• void