Its first noted appearance was in 239 B.C., but it was British astronomer Edmund Halley (1656–1742) who noted that the bright comet he observed in 1682 followed roughly the same path as those that had been observed in 1531 and 1607. He suggested that they were all the same comet and that it would reappear in 1758. It did reappear, and it was therefore named for Halley, who was England’s second astronomer royal. Thanks to Halley, the common man could rest a bit easier at night: Before the British astronomer proved, through his observations and previous astronomical data, that comets are natural objects subject to the laws of gravity, people had viewed occurrences of comets as harbingers of doom. Halley’s comet has been observed by astronomers every time it has appeared since 239 B.C. Most recently seen in 1985 and 1986, the comet will make another appearance in 2061, and roughly every 76 years thereafter.

It’s also worth noting that it was Halley who encouraged his friend and fellow scientist Sir Isaac Newton (1642–1727) to write his theory of gravity, which he did: Principia mathematica, which Halley used his own money to publish, appeared in 1687 and is considered a seminal work of modern science.