This interactive is used in Chapter 20. They pulsate with amazing regularity, on time scales ranging up to a few seconds per pulse. Their initial discovery brought short-lived conjecture about messages from extra-terrestrials. They are neutron stars, the remnants of massive, dead stars. But not every neutron star is observed to blink, even though astronomers now believe that they all do. Why? This Interactive lets you manipulate the star’s magnetic and spin axes to find out for yourself.