Halley’s Comet passes by Earth about every 76 years. In the 1700s, astronomer Edmond Halley, after whom the comet is named, used Sir Isaac Newton’s gravitational theories to predict comet’s recurring orbit. Scientists believe the comet has been moving through the solar system for about 200,000 years. The earliest possible sighting of the comet could date back to 466 B.C.
In 1910, French astronomer Camille Flammarion said a poisonous gas in the comet’s tail could “impregnate the atmosphere and snuff out all life on the planet.” While other scientists refuted Flammarion’s claim, some people sealed their homes and bought gas masks. The comet last passed by in 1986 and is expected to have a brighter return in 2061.
Andrews, E. (2016, November 08). A Brief History of Halley's Comet. Retrieved November 04, 2017, from http://www.history.com/news/a-brief-history-of-halleys-comet-sightings
Schultz, K. (2014, June 11). Is Seeing a Comet Like Halley's a Once-in-a-Lifetime Event? Retrieved November 04, 2017, from https://www.scientificamerican.com/gallery/is-seeing-a-comet-like-halley...