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What Is a Pulsar?

Pulsars are compact, rapidly rotating objects that emit concentrated streams of radiation far across the cosmos.

Most appear to be incredibly dense neutron stars, though in 2017 a slower spinning white dwarf pulsar was identified after years of searching.


Pulsars channel electromagnetic radiation into bright, laser-like beams from both their north and south poles thanks to magnetic fields that are as much as a quadrillion times stronger than Earth's. It's not clear where this light comes from, with several sources possibly responsible for the spectrum of light.

As they rotate on a geographical axis, these beams swivel in an arc. To any observer in the path of this circling stream of light, the star will appear to 'pulse' with radiation.

Most pulsars rotate at incredibly high speeds, anywhere between once a second to hundreds of times a second. This precise regularity confused astronomers Jocelyn Bell and Anthony Hewish, who rather playfully referred to them as 'LGM' (or 'little green men') after observing the flicker of a pulsar's radio waves for the very first time in 1967.

Why are pulsars important in astronomy?

Since their initial discovery, more than 2,000 pulsars have been recorded. Their narrow jets of broad spectrum radiation provide astronomers with information that could tell them a great deal about the behaviour and make-up of super dense objects such as neutron stars.

Their precise rotations are rivalled only by atomic clocks, making them perfect as galactic lighthouses, marking locations and time while also acting as measuring sticks for various gravitational phenomena.

This 'clock' also makes them useful for both measuring long distances across space and conducting experiments on space and time to test the limits of models based on relativity.


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