They signal to us across thousands of light-years, pulsing
through the cosmic static like a vinyl record that’s reached the
end of its songs....like the furious rhythm of a tom-tom....or
like the whine of an electric motor.... These are the calls of
pulsars — the remnants of once-mighty stars that emit beams of
energy like cosmic lighthouses. A pulsar is born when the core
of a massive star stops producing energy. It collapses, forming
a neutron star. Such a stellar remnant is more massive than the
Sun, but only a few miles in diameter. A chunk of its matter the
size of a thimble would weigh billions of tons. As the core
collapses, it spins faster, like an ice skater who pulls in her
arms — up to dozens of revolutions every second. It also
generates a powerful magnetic field. As the newborn neutron star
spins, particles trapped in the magnetic field emit beams of
energy from the magnetic poles — often in the form of radio
waves. If Earth lies in the path of one of the beams, telescopes
detect rapid pulses of