Edmund Halley - biographical facts

  Edmund Halley (1656-1742) was an English astronomer. He was born near London. His father was a wealthy soap boiler. Young Edmund was sent to St. Paul's School and to Queen's College, Ox­ford. He was a mathematical genius, nothing less. While a mere lad he noted the variation of the compass. At nineteen he computed the orbits of the planets. Becoming convinced that a more accurate determination of the position of the fixed stars was essential to progress in astronomy, he left the northern hemisphere to others already at work and prepared a cat­alogue of 360 stars visible in the southern hemisphere, thus winning the name of "Southern Tycho." Halley resided for a time at St. Helena, and noted that the London pendulum was too long for St. Helena; i. e., that the standard pendulum loses time when it is carried toward the equator, and hence farther from the center of the Earth.
   Halley was acquainted with Newton and stimulated him to publish his Principia— a great work on astronomy. Halley held various crucial positions—director of the mint, professor of geometry at Oxford, and, to pass by others, astronomer royal at Greenwich. Interest in Halley was revived in 1909-10 by the return of Halley's Comet, named for him.

   Halley became interested in computing the orbits of the comets that had appeared between the years 1480-1680. He discovered. what was not known previously, that comets follow regular orbits and return with regularity, and that the reason that a comet is not visible all the time is that, during the greater part of its orbit about the Sun, it is too far away to be seen. The comet that now bears his name passed within 11,000,000 miles of the sun in 1682. Halley laid out its path; declared that it was the same comet that had caused consternation in 1607; and predicted its return in 1758. "And when it really appears," said he," do not forget that it was an Englishman who made the first prediction of the return of any comet."
   Halley died sixteen years before the time, but the comet came in sight on Christmas Day of the appointed year. It appeared again in 1835, and, as stated, in 1909. Halley's Comet is visible to the eye only a few weeks, and may be seen through' the telescope for a few months only. It requires 78.8 years to complete a revolution in its orbit.