Halleys Comet

Halley's Comet. This comet was observed in 1682 by the astronomer Halley, who had powerful reasons for believing that it was the same comet that had appeared previously in the years 1607 and 1531. He inferred that this heavenly body moved in an elliptical orbit round the sun in the same manner as any one of the planets, but with a far larger orbit. His ideas being, confirmed by careful calculations, he ventured to predict that the comet would next appear in 1757 or 1758, possibly retardation from unknown causes delaying it till 1759. The mathematician Clairaut investigated the subject in greater detail in 1758, and further predicted that the comet would first reach its nearest position to the sun about the middle of.April, 1759, adding that his calculations might be in error about a month either way. The comet actually appeared on Christmas Day, 1758, and was closest to the sun on the 12th March, just a month earlier than the day which Clairaut had calculated to be the most likely. It has since been shown that the magnificent comet appearing B.C. 11 was identical with Halley's. The next return will probably be in 1910. [Comet.]