(astronomy) A pulsar is an extremely dense astronomical body more massive than our Sun but not larger than 20 kilometers in diameter, essentially composed of neutrons with an iron shell. This astronomical body pulsates at very regular intervals, from a few milliseconds to more than one second : its name is a portmanteau-word coming from pulsating star.
When the first pulsar was detected, its pulsating period was so regular that scientists first believed it came from an extraterrestrial civilization.
