Pulsar planet. Artwork of a pulsar (upper right, with beams coming out of it) seen from one of several hypothetical planets orbiting it. Pulsars are rapidly-rotating neutron stars which emit radio waves in two narrow beams. They are only seen from Earth if one of these beams crosses Earth during the pulsar's rotation. Here, the pulsar's extreme radiation is causing minerals on the planet to fluoresce. The other planets (upper right) in the system are also fluorescing. Pulsars are formed in supernova explosions. As a supernova would destroy any planets around it, the planets must have formed since the explosion.