The field of astronomy is filled with many notable names and one of them is Edmund Halley. Halley was an Englishman who was a geophysicist, mathematician, astronomer, and meteorologist. He was the second Astronomer Royal in Great Britain after John Flamsteed and is best known for having computed the orbit of the famous Halley’s Comet (named after him). He was a man of many accomplishments, designed several inventions and was an intrepid discoverer.
His Early Life
Edmund Halley was born in England on November 8, 1656. He was the son of Edmond Halley Sr. who was a very successful soap-maker in London. His family was originally from Derbyshire. As a young child, Edmund was interested in math and began his education at St Paul’s School, London. In 1673, he enrolled at Oxford Queen’s College. During his undergraduate years he spent a great deal of his time publishing papers on sunspots and the Solar System.
His Early Career and Travels
In 1675, Halley became the assistant for John Flamsteed who was first Astronomer Royal at Greenwich Observatory. One of Halley’s many tasks was to assign numbers to stars using Flamsteed’s number system for identification and cataloguing purposes. A year later, he travelled to the volcanic tropical island Saint Helena, in the South Atlantic Ocean. He brought with him a large sextant and some telescopic sights so he could set up an observatory and study and catalogue the stars in the Southern Hemisphere. It was during his stay in St. Helena that he carefully observed the transit of Mercury across the sky. He realized that Venus, moving in the same way, could then be used to calculate the size of the Solar System.
Halley returned to England in 1678 and a year later he went to Danzig at the request of the Royal Society to help resolve a dispute between Robert Hooke and Johannes Hevelius. As Hevelius did not utilize a telescope in his observations, Robert Hooke questioned his findings. Halley stayed with Hevelius to observe his findings and verify his conclusions.
That same year in 1679, Halley published “Cataogue Stellarum Australium”, a catalogue of the Southern Hemisphere stars which he observed while in St. Helena. His publication was so extensive that it included 341 stars that could be viewed only in the Southern Hemisphere. Flamsteed gave him the title “The Southern Tycho” in reference to the well-known sixteenth century astronomer, Tycho Brahe. Halley also attained his Master’s Degree from Oxford and was elected as a Royal Society Fellow aged 22.
He married Mary Tooke in 1682 and they had three children together.
In 1686, Halley’s second work was published; a paper with charts on monsoons and trade winds also derived from his Helenian expedition. He concluded that solar heating was behind atmospheric motions and he established that there was a close relationship between sea level height and barometric pressure. His useful charts helped define the emerging field of information visualization.
Halley conducted many lunar observations which took up most of his time. Aside from his lunar studies, he also became interested with problems relating to gravity. One issue in particular that concerned him was finding a proof for the laws of planetary motion. In 1684, he travelled to Cambridge to talk the issue over with Sir Isaac Newton, only to find out that Newton had already managed to solve the problem, stating that the planets’ orbits would be elliptical. Halley naturally wanted to see the calculations Newton used but Newton wasn’t able to locate them. Newton then wrote a short treatise entitled “On the Motion of Bodies in an Orbit” in 1684 which explained his calculations. This work was later expanded on by Newton, becoming the famous work “Philosophiæ Naturalis Principia Mathematica” in 1687 which Halley helped to publish.
Calculations and Inventions
Halley’s first orbit calculations were of the Kirch Comet making use of John Flamsteed’s observations in 1680 and 1681. The comet had first been discovered by Göttfried Kirch on 14 November 1680. Halley calculated the orbit of the Kirch Comet in 1682 however his calculations weren’t completely accurate.
In 1691, Edmund Halley invented a diving bell which he and his colleagues tested extensively. It used leather tubes and lead-lined barrels to supply fresh air underwater. Halley was known as one of the earliest cases for middle ear trauma since he would stay underwater for periods that lasted up to 4 hours. The same year that he designed an early working model of a magnetic compass.
In 1693, he published an article on life annuities, including a report on ‘age at death’, heralding the beginning of actuarial science.
Later Life and Comet Predictions
In 1698, he was given permission to take command of the sailing ship Paramour and travel to the South Atlantic Ocean to find out more about the laws that govern the variation of the compass. The first expedition was cut short due to unrest among the crew and a second expedition began in 1699. His magnetic charts of Atlantic Ocean and parts of the Pacific Ocean were published in “General Chart of the Variation of the Compass” in 1701.
In 1704, Halley finally became Savilian Professor of Geometry at the University of Oxford, after missing out on this prestigious appointment earlier in his career. He published “Synopsis Astronomia Cometicae” (A Synopsis of the Astronomy of Comets) in 1705. This work detailed the parabolic orbits of 24 comets that had been observed from 1337 to 1698. It also stated that the comet sightings of 1531, 1607, and 1682 were of the same comet, which orbits the sun every 75-76 years and he correctly predicted it would return in 1758. When the comet did return it became known as Halley’s Comet.
He devised a method of observing the transit of Venus across the sun which would next be observed in 1761 and 1769. These observations would then be used to make an accurate calculation of the distance from the Earth from the sun.
Halley became Astronomer Royal at Greenwich Observatory, succeeding John Flamsteed in 1720.
He died on January 14, 1742 aged 86 and sadly, did not live to see the return of the comet that was named in his honor. Halley’s Comet will next appear in the night sky in the year 2062.