The Story Behind a Once-in-a-Lifetime Green Comet That's About to Fly Past Earth

The Space Doctor on Instagram: "Halley's Comet is the only known short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years.It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061. Officially designated 1P/Halley, it is also commonly called Comet Halley, or sometimes simply Halley. Astronomers have now linked the comet's appearances to observations dating back more than 2,000 years. Halley was last seen in Ear