S. del Palacio

The lighthouse stays silent most of the time, but occasionally it emits a flare so bright it can be seen from hundreds of thousands of kilometers away. That's exactly how the magnetar XTE J1810-197 behaves — an ultra-dense star with a monstrous magnetic field.

After a supernova explosion, a neutron star neutron star remains: a city-sized ball of unimaginably dense matter, spinning hundreds of times per second. Any tiny bump on its surface would make it wobble like an off-balance spinning top, humming faintly through the fabric of space.