quasar

American  

[kwey-zahr, -zer, -sahr, -ser] / ˈkweɪ zɑr, -zər, -sɑr, -sər /

noun

Astronomy.

• quasars
  plural

1. one of over a thousand known extragalactic objects, starlike in appearance and having spectra with characteristically large redshifts, that are thought to be the most distant and most luminous objects in the universe.

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quasar British  

/ ˈkweɪzɑː, -sɑː /

noun

1. any of a class of extragalactic objects that emit an immense amount of energy in the form of light, infrared radiation, etc, from a compact source. They are extremely distant and their energy generation is thought to involve a supermassive black hole located in the centre of a galaxy

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quasar Scientific  

/ kwā′zär′ /

1. Short for quasi-stellar radio source. A compact, starlike celestial body with a power output greater than our entire galaxy. Believed to be the oldest and most distant objects ever detected, quasars are billions of light-years from Earth and moving away from us at nearly 80 percent of the speed of light. For this reason, quasars are highly important to astronomers' understanding of the early universe. Little is currently understood about the nature of quasars; one theory suggests that they are produced by giant black holes destroying enormous amounts of matter, causing the subsequent ejection of radiation along their north and south poles. Many astronomers believe that quasars represent an early stage in the evolution of galaxies such as our own.

2. See also blazar Seyfert galaxy

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Other Word Forms

Noun Inflected Forms

• quasars
  plural

Etymology

Origin of quasar

1960–65; quas(i-stell)ar, in quasi-stellar radio source, the first type of quasar discovered

Compare meaning

How does quasar compare to similar and commonly confused words? Explore the most common comparisons:

• quasar vs. pulsar

Explanation

A quasar is a starlike object in space that may emit energy, light, and radio waves. In the vastness of the universe, there are many bodies such as planets, moons, asteroids, and suns. Another type of object is the quasar. Quasars are a lot like suns, though much smaller. Quasars have large redshifts, which means the light from the quasar increases in frequency, moving to the red part of the light spectrum. Quasars are powerful and usually produce a lot of radiation. Don't mess with a quasar!

Example Sentences

See Examples For:

quasar quasars

By observing a quasar from the early universe, the researchers found strong evidence that this influence reaches much farther than previously thought.

From Science Daily ● Mar. 30, 2026

The relationship between super-Eddington growth and jet-driven feedback is still not well understood, and this quasar provides a valuable reference point for testing new ideas.

From Science Daily ● Jan. 24, 2026

The team suggests the quasar may be observed during a short transitional period, possibly following a sudden influx of gas.

From Science Daily ● Jan. 24, 2026

Although quasar activity peaked in the early Universe, quasars were rare and spread apart by hundreds of millions of light years.

From Space Scoop ● Jul. 4, 2025

Modern radio telescopes are exquisitely sensitive; a distant quasar is so faint that its detected radiation amounts perhaps to a quadrillionth of a watt.

From "Cosmos" by Carl Sagan

Its work in tracking spacecraft in the early space race, and its research into quasars, pulsars and gravitational lenses, is also part of its outstanding scientific heritage.

From BBC ● Sep. 1, 2026

The structure underlying GPS uses distant quasars to locate places on Earth.

From The Wall Street Journal ● Aug. 7, 2026

So scientists anchor the world’s coordinates to far-off stillness: quasars, the luminous cores of galaxies billions of light-years away, observed nightly by radio telescopes across multiple continents and cross-checked with lasers bounced off satellites.

From The Wall Street Journal ● Aug. 7, 2026

Some of these newly discovered quasars date to a time when the universe was only about 5% of its current age.

From Science Daily ● Jul. 9, 2026

In considering the quasars, we confront profound mysteries.

From "Cosmos" by Carl Sagan