pulsar

American  

[puhl-sahr] / ˈpʌl sɑr /

noun

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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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

"There's a bright band, then nothing, bright band, nothing. No other pulsar shows this kind of striation. That uniqueness made the Crab Pulsar especially interesting -- and challenging -- to understand."

From Science Daily • Mar. 28, 2026

"Results like these help not just pulsar science, but other fields of astronomy as well, including SETI."

From Science Daily • Jan. 6, 2026

Correcting for these tiny, ever-changing delays is essential for keeping pulsar timing as accurate as possible.

From Science Daily • Jan. 6, 2026

Much like stars shimmer when seen through Earth's atmosphere, pulsar radio signals also flicker as they move through space.

From Science Daily • Jan. 6, 2026

It is perhaps conceivable that a planet could survive the evolution of a star into a pulsar; or a planet could be captured at a later time.

From "Cosmos" by Carl Sagan