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

His research showed that plasma around the pulsar bends and spreads electromagnetic waves through diffraction, helping form the pattern.

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

Because of the possible scientific significance, researchers are now analyzing additional follow up observations to determine whether the pulsar candidate is genuine.

From Science Daily • Feb. 17, 2026

In earlier stages, material from the companion flowed onto the pulsar, increasing its spin and fueling a powerful wind.

From Science Daily • Jan. 1, 2026

This is the reason it is called a pulsar.

From "Cosmos" by Carl Sagan