Dead stars keep better time than watches
Pulsars are rotating neutron stars. Their radio beams sweep like a lighthouse, some of them with a stability that rivals atomic clocks.
Established2 min read
The 1967 signal was so regular it was half-seriously tagged LGM, little green men. The discovery of more of them, in the plane of the galaxy, ended that. A neutron star’s magnetic axis is offset from its spin. Each turn flashes Earth if the beam crosses us.
Millisecond pulsars, spun up by a companion, are timed so well that arrays of them are used to hunt gravitational waves with periods of years. The corpse of a supernova is a metronome. The first one found is still pulsing.
Caveats
- Not every neutron star points at us, so not every neutron star is a pulsar from here.
- ‘Better than an atomic clock’ fits the best millisecond pulsars over long averages, not a wristwatch comparison on a Tuesday.
Sources
- 1Hewish A., Bell S. J., Pilkington J. D. H., Scott P. F., Collins R. A.. Observation of a Rapidly Pulsating Radio Source. Nature 217, 1968.