Neutron stars were first theorized in the 1930s, soon after the discovery of the neutron. In the 1960s, regular radio pulses from space were detected. Their origin was unknown, and some scientists thought these pulses might be evidence of extraterrestrial life. Later, it was discovered that the regular signals were caused by a pulsar, a type of neutron star.
(Image: © by Karl Tate, Infographics Artist)