Famous Astronomers: The Great Halley

Born in 1656, Edmund Halley was only 14 years younger than Isaac Newton. The two of them became friends and collaborators. As a child, like so many great astronomers before him, Halley was quite advanced in the area of the mathematics, his reputation following him to Oxford upon entering college.

 

The subject in which Halley found the most interest in, however, was astronomy. Halley excelled in the subject, and up to the time of Kepler, philosophers had assumed almost as an axiom that the heavenly bodies must revolve in circles and that the motion of the planet around the orbit, which it described, must be uniform.

 

Kepler was, however, unable to shake himself free from the prevailing notion that the angular motion of the planet ought to be of a uniform character around some point. He had indeed proved that the motion round the focus of the ellipse in which the sun lies is not of this description. One of his most important discoveries even related to the fact that at some parts of its orbit a planet swings around the sun with greater angular velocity than at others. But it so happens that in elliptic track, which differ but little from circles, as is the case with all the more important planetary orbits, the motion round the empty focus of the ellipse is very nearly uniform.

 

It seemed natural to assume that this was exactly the case, in which event each of the two foci of the ellipse would have had a special significance in relation to the movement of the planet.

 

The youthful Halley, however, demonstrated that so far as the empty focus was concerned, the movement of the planet around it, though so nearly uniform, was still not exactly so. At the age of 19, he published a treatise on the subject which at once placed him in the foremost rank among theoretical astronomers. And at the age of 20, before even obtaining his university diploma, Halley ventured to the southern hemisphere to study the stars around the South Pole.

 

After finally settling in England, Halley published an important paper on the variation of the magnetic compass. In 1692, Halley explained his theory of terrestrial magnetism. But it wasn't until he convinced King William III to allow him to set sail that he was able to test his theory and observe magnetic variation of the compass for himself. The mission, though, was short-lived after several members of the crew got sick and another member mutinied. After returning back to England, Halley set sail once more and published a general chart that showed the variation of the compass t the different places he visited.

Probably the greatest service that Halley ever rendered to human knowledge was the share in which he took in bringing Newton's "Principia" before the world. It was, after all, Halley who had convinced Newton to publish his findings on gravitation.

 

But Halley would become most famous for successfully calculating when a comet would return--17 years after his death. This is where we get the term "Halley's Comet."

 

 

Ball, R.S. (2000).Avoid Great Astronomers. Retrieved March 14, 2008, from the Gutenburg Project Web site: http://www.gutenberg.org/dirs/etext00/grast11.txt.