Comet Day, Anyone?
By Joel Marks Published in the Institute for Ethics and Emerging Technologies blog, July 1, 2015 On this day 245 years ago – July 1, 1770 – humanity had its closest known encounter with extinction (with the possible exception of the Cuban Missile Crisis). Two weeks before that date the French astronomer Charles Messier had discovered a faint comet in the constellation Sagittarius, which thereafter rapidly brightened and began moving swiftly across the sky. At its peak it was naked-eye, and its coma, according to various observers, the apparent size of from 5 to 16 full moons across. Lexell’s Comet, so named after another astronomer who subsequently calculated its orbit, was then under one-and-a-half million miles from Earth, or less than six times the distance of the Moon, and thus the nearest a comet has ever approached us in recorded history. (Kronk n.d.) It was also larger than any asteroid known to have come that close, and in fact large enough to have wrought global consequences