Re: When was Halley's Comet first seen

Written records about when Halley’s Comet was first seen are a bit sketchy. According to one source, Halley's Comet has been known since at least 240 BC and possibly since 1059 BC (so it has been known for at least 2,240 years!). The first well-documented sighting of the comet occurred in 1066 AD when it appeared just before the Battle of Hastings.

Edmund Halley, an English astronomer and mathematician, first mathematically deduced the comet’s orbital period in 1705 using Isaac Newton’s laws of motion (the orbital period is the time it takes something to go all the way around the sun). He predicted that the comet seen in 1531, 1607, and 1682 would return in 1758. And Halley was right! Unfortunately, he died in 1742 and never saw his prediction come true. The comet, as Halley showed, has an orbital period of 76 years. And even though Halley didn’t discover the comet, it was named after him because he successfully predicted its reappearance in 1758. Halley’s Comet last appeared in 1986.

You can check the following web sites for more information:

http://planetscapes.com/solar/eng/halley.htm
http://seds.lpl.arizona.edu/nineplanets/nineplanets/halley.html