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Why does a pulsar beam resemble the beam of a lighthouse?

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Detail of the Cygnus Loop.This nebula is the product of a supernova explosion; in this section, the blast wave has encountered an area of dense interstellar gas, creating turbulence in the wave and causing it to glow. The picture is a composite of three images taken by the Hubble Space Telescope. — Supernova remnant Detail of the Cygnus Loop.
This nebula is the product of a supernova explosion; in this section, the blast wave has encountered an area of dense interstellar gas, creating turbulence in the wave and causing it to glow. The picture is a composite of three images taken by the Hubble Space Telescope.

A pulsar beam resembles the beam of a lighthouse because of the way the neutron star emits and directs its radiation.12

As a pulsar rotates, it releases intense beams of electromagnetic radiation from its magnetic poles. Because these magnetic poles do not align with the star's rotational poles, the rotation causes these radiation beams to sweep through space like the rotating light of a lighthouse.12

When these beams happen to sweep across the line of sight of an observer on Earth, they are detected as a series of regular, rhythmic pulses. This effect is a direct result of the star's rapid rotation and the specific geometry of its magnetic field, which concentrates the emission into narrow beams rather than radiating it uniformly in all directions.12