Comets have long been associated with astrology, or the study of the heavens for the purpose of predicting the future. Their appearance in the sky has been associated with prophecies of destruction and important shifts in culture. This is largely due to the sometimes unpredictable orbits of comets and their fantastical appearance in the sky.
While most people no longer react to comets with the same fear and misapprehension, some cultures in the world today still look to them as portents of disasters and as objects of religious significance.
Ancient Comets
Perhaps the earliest record of a comet sighting is in China in 1059 B.C. At that time, two kings named Wu-Wang and Chou Hsin were engaged in a war over territory. The Chinese astrological history relates a story of how a comet appeared in the sky during the clash of these two men, symbolizing the epic power struggle between the two kings.
Another comet sighting in the early days of civilization was in 974 B.C. This comet may have Biblical significance, as it seems to coincide with David’s account of a sword hung over Jerusalem around the same time:
And David lifted up his eyes, and saw the angel of the Lord standing between the earth and the heaven, having a drawn sword in his hand stretched out over Jerusalem. (I Chronicles 21:16)
Comets Imagined as Swords
The Great Comet of 372 B.C. was considered to be a harbinger of impending doom. The comet was thought to have brought about a catastrophic earthquake and tidal wave in Achaea. Additionally, this comet may have been the first example of “comet splitting”, wherein a comet’s nucleus breaks into two or more pieces without discontinuing its orbit. This “splitting” was especially evident in the collision of Shoemaker-Levy 9 with Jupiter in 1994.Classical Comets
Aristotle and Ptolemy
This treatment of comets was not universal, however. Seneca the Younger, an advisor to Emperor Nero, proposed the idea that comets were in fact heavenly bodies. His studies were based on research and study of the Babylonians’ astronomical observations as well as older classical thoughts on the subject. However, because of the popularity and stellar reputations of Ptolemy and Aristotle, Seneca’s theories on comets were marginalized into the 16th century A.D.
Seneca the Younger
Medieval Comets
Woodcut of Townspeople Observing the Great Comet of 1577
The most notable occurrence of the medieval ages in regard to comets was the Great Comet of 1577. It was an abnormally bright comet which was visible from Earth for a period of approximately 74 days. This event is notable not only for the brilliance of the comet’s appearance, but also because several astronomers used various methods to disprove the theories put forth by Ptolemy and Aristotle. These figures include Michael Mästlin, who used rudimentary parallax calculations to determine that comets were in fact celestial objects; Tycho Brahe, who was able to determine the position of the comet with greater (but still vague) accuracy in addition to determining that the orbit of the comet was not circular, but oblong; and William IV, Landgrave of Hesse Cassel, whose own observations were used in conjunction with those of Brahe in validating his theory of the position of the comet being far beyond the moon.
Tycho Brahe
The Nineteenth Century
Johann Encke
Comet Encke, named after Johann Encke, was observed separately in 1786, 1795, and 1805, without anyone successfully linking the sightings together as the orbit of one comet. In 1819, Encke successfully used a mathematical process called an "integration," of the comet’s orbit, backwards. This allowed him to determine that these sightings were in fact of the same heavenly body. After his prediction of the next appearance of the comet was proven correct, Encke went on to accurately foretell the next two times the comet would approach perihelion. He also developed an accurate theory for determining the orbits of heavenly bodies. Using this theory, Marie Charles Theodor Damoiseau and Giovanni Santini separately predicted the return of Comet Biela in late November of 1832.
A link between comets and meteor showers was suspected for a long time, but was only seriously considered by astronomers after the meteor shower of November 27, 1872. The shower was recognized as debris from the Comet Biela. Following this identification, the Leonid and Perseid showers were both discovered to be linked to the Earth passing through the path of comets. Among the influential people in determining this were Denison Olmsted, who observed that the Leonids seemed to be originating from the same place in the sky; Urbain La Verrier, who first linked the orbital period of the Leonids with the orbit of a comet; and Carl F. W. Peters, who successfully identified that the Leonids were remnants from Oppolzer’s comet.
A link between comets and meteor showers was suspected for a long time, but was only seriously considered by astronomers after the meteor shower of November 27, 1872. The shower was recognized as debris from the Comet Biela. Following this identification, the Leonid and Perseid showers were both discovered to be linked to the Earth passing through the path of comets. Among the influential people in determining this were Denison Olmsted, who observed that the Leonids seemed to be originating from the same place in the sky; Urbain La Verrier, who first linked the orbital period of the Leonids with the orbit of a comet; and Carl F. W. Peters, who successfully identified that the Leonids were remnants from Oppolzer’s comet.
To Learn More:
Space.com: Bronze Age Comet
Comets: A Chronological History of Observation, Science, Myth, and Folklore, by Donald Yeomans. (Amazon Link) (HOLLIS Link)