pulsar

American  

[puhl-sahr] / ˈpʌl sɑr /

noun

pulsars plural

1. Astronomy. one of several hundred known celestial objects, generally believed to be rapidly rotating neutron stars, that emit pulses of radiation, especially radio waves, with a high degree of regularity.

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pulsar British  

/ ˈpʌlˌsɑː /

noun

1. any of a number of very small extremely dense objects first observed in 1967, which rotate very rapidly and emit very regular pulses of polarized radiation, esp radio waves. They are thought to be neutron stars formed following supernova explosions

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pulsar Scientific  

/ pŭl′sär′ /

1. A rapidly spinning neutron star that emits radiation, usually radio waves, in narrow beams focused by the star's powerful magnetic field and streaming outward from its magnetic poles. Because the pulsar's magnetic poles do not align with the poles of its rotational axis, the beams of radiation sweep around like the beacon of a lighthouse and are thus observed on Earth as short, regular pulses, with periods anywhere between 1 millisecond and 4 seconds.

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pulsar Cultural  

1. A rapidly rotating neutron star. The radiation from such a star appears to come in a series of regular pulses (one per revolution), which explains the name.

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Other Word Forms

Noun Inflected Forms

• pulsars
  plural

Etymology

Origin of pulsar

1965–70; puls(ating st)ar, on the model of quasar

Compare meaning

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

• quasar vs. pulsar

Explanation

A pulsar is a small, dense star that emits a beam of electromagnetic radiation in a pulsing pattern as it rotates. Like a lighthouse light, the energy from a pulsar can be observed when it's pointing toward Earth. Astronomers discovered pulsars in the 1960s, and they're still not sure exactly how they emit such huge amounts of radiation. They do know that pulsars spin, and that the "pulses" of energy have regular, precise spaces between them. Some pulsars emit radio waves, while others produce gamma ray or x-ray wavelengths. Pulsar comes from "pulse" or "pulsating star," and is modeled after quasar.

Example Sentences

See Examples For:

pulsar pulsars

"Quantitatively, there may be refinements. For example, the current treatment includes gravity in a static, lowest-order approximation. The pulsar is rotating, and including rotational effects could introduce quantitative changes, though not qualitative ones."

From Science Daily ● Mar. 28, 2026

When undisturbed by outside forces, the radio pulses from a pulsar reach Earth with remarkable consistency.

From Science Daily ● Feb. 17, 2026

"We're looking forward to what follow-up observations might reveal about this pulsar candidate," Perez said.

From Science Daily ● Feb. 17, 2026

They change as the pulsar, the intervening gas, and Earth all move relative to one another.

From Science Daily ● Jan. 6, 2026

Perhaps the recipients will make nothing of it, or think it is a recording of a pulsar, which in some superficial sense it resembles.

From "Cosmos" by Carl Sagan

So far, astronomers have identified only a few thousand neutron stars, most of them detected as pulsars.

From Science Daily ● May 15, 2026

Because of this steady rhythm, pulsars function like highly reliable cosmic clocks.

From Science Daily ● Feb. 17, 2026

This project represents one of the most sensitive radio investigations ever carried out to search for pulsars in the turbulent central region of the Milky Way.

From Science Daily ● Feb. 17, 2026

By analyzing how bright pulsars appear across different GLEAM-X frequencies, astronomers hope to learn more about how these objects produce radio waves and where they are distributed throughout the Milky Way.

From Science Daily ● Jan. 24, 2026

They pay almost no attention to all the moons and planets, asteroids and comets, quasars and pulsars, exploding galaxies, symbiotic stars, cataclysmic variables and X-ray sources that have been discovered since Ptolemy’s time.

From "Cosmos" by Carl Sagan