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Caesar's Comet AI simulator
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Hub AI
Caesar's Comet AI simulator
(@Caesar's Comet_simulator)
Caesar's Comet
Caesar's Comet (also Sidus Iulium ("Julian Star"); Caesaris astrum ("Star of Caesar"); Comet Caesar; the Great Comet of 44 BC; numerical designation C/−43 K1) was a seven-day cometary outburst seen in July 44 BC. It was interpreted by Julius Caesar's contemporaries in Ancient Rome as a sign of the deification of the recently assassinated dictator (100–44 BC).
Based on two questionable reports—one from China (May 30) and another from Rome (July 23)—an infinite number of orbit determinations can fit the observations, but a retrograde orbit is inferred based on available notes. The comet approached Earth both inbound in mid-May and outbound in early August. It came to perihelion (closest approach to the Sun) on May 25, −43 at a solar distance of about 0.22 AU (33 million km). At perihelion the comet had a solar elongation of 11 degrees and is hypothesized to have had an apparent magnitude of around −3 as the Chinese report is not consistent with daytime visibility during May. Between June 10 and July 20 the comet would have dimmed from magnitude +1 to around magnitude +5. Around July 20, −43, the comet underwent an estimated 9 magnitude outburst in apparent magnitude and had a solar elongation of 88 degrees in the morning sky. At magnitude −4 it would have been as bright as Venus.
As a result of the cometary outburst in late July, Caesar's Comet is one of only five comets known to have had a negative absolute magnitude (for a comet, this refers to the apparent magnitude if the comet had been observed at a distance of 1 AU from both the Earth and the Sun) and may have been the brightest daylight comet in recorded history.[verification needed]
In the absence of accurate contemporary observations (or later observations confirming an orbit that predicts the earlier appearance), calculation of the comet's orbit is problematic and a parabolic orbit is conventionally assumed. (In the 1800s a possible match with the Great Comet of 1680 was speculated which would give it a period of about 575 years. This has not been confirmed because the later observations are similarly insufficiently accurate.) The parabolic orbital solution estimates that the comet would now be more than 800 AU (120 billion km) from the Sun. At that distance, the Sun provides less light than the full Moon provides to Earth.
Caesar's Comet was known to ancient writers as the Sidus Iulium ("Julian Star") or Caesaris astrum ("Star of Julius Caesar"). The bright, daylight-visible comet appeared suddenly during the festival known as the Ludi Victoriae Caesaris—for which the 44 BC iteration was long considered to have been held in the month of September (a conclusion drawn by Edmund Halley). The dating has recently been revised to a July occurrence in the same year, some four months after the assassination of Julius Caesar, as well as Caesar's own birth month. According to Suetonius, as celebrations were getting underway, "a comet shone for seven successive days, rising about the eleventh hour, and was believed to be the soul of Caesar."
The Comet became a powerful symbol in the political propaganda that launched the career of Caesar's great-nephew (and adoptive son) Augustus. The Temple of Divus Iulius (Temple of the Deified Julius) was built (42 BC) and dedicated (29 BC) by Augustus for purposes of fostering a "cult of the comet". (It was also known as the "Temple of the Comet Star".) At the back of the temple a huge image of Caesar was erected and, according to Ovid, a flaming comet was affixed to its forehead:
To make that soul a star that burns forever
Above the Forum and the gates of Rome.
Tracing the coinage from 44 BC through the developing rule of Augustus reveals the changing relationship of Julius Caesar to the Sidus Iulium. Robert Gurval notes that the shifting status of Caesar's Comet in the coinage follows a definite pattern. Representations of the deified Julius Caesar as a star appeared relatively quickly, occurring within several years of his death. About twenty years passed, however, before the star completed its transformation into a comet. Starting in 44 BC, a money maker named P. Sepullius Macer created coins with the front displaying Julius Caesar crowned with a wreath and a star behind his head. On the back, Venus, the patron goddess of the Julian family, holds a starred scepter. Gurval maintains that this coin was minted about the time of Caesar's assassination and thus probably would not have originally referred to his deification. As it circulated, however, it would have brought that idea to mind because of Caesar's new cult. Kenneth Scott's older work The Sidus Iulium and the Apotheosis of Caesar contests this by assuming that the comet did indeed spark this series because of similarity to other coins he produced. A series of Roman aurei and denarii minted after this cult began show Mark Antony and a star, which most likely represents his position as Caesar's priest. In later coins likely originating near the end of Octavian's war with Sextus Pompey, the star supplants Caesar's name and face entirely, clearly representing his divinity.
Caesar's Comet
Caesar's Comet (also Sidus Iulium ("Julian Star"); Caesaris astrum ("Star of Caesar"); Comet Caesar; the Great Comet of 44 BC; numerical designation C/−43 K1) was a seven-day cometary outburst seen in July 44 BC. It was interpreted by Julius Caesar's contemporaries in Ancient Rome as a sign of the deification of the recently assassinated dictator (100–44 BC).
Based on two questionable reports—one from China (May 30) and another from Rome (July 23)—an infinite number of orbit determinations can fit the observations, but a retrograde orbit is inferred based on available notes. The comet approached Earth both inbound in mid-May and outbound in early August. It came to perihelion (closest approach to the Sun) on May 25, −43 at a solar distance of about 0.22 AU (33 million km). At perihelion the comet had a solar elongation of 11 degrees and is hypothesized to have had an apparent magnitude of around −3 as the Chinese report is not consistent with daytime visibility during May. Between June 10 and July 20 the comet would have dimmed from magnitude +1 to around magnitude +5. Around July 20, −43, the comet underwent an estimated 9 magnitude outburst in apparent magnitude and had a solar elongation of 88 degrees in the morning sky. At magnitude −4 it would have been as bright as Venus.
As a result of the cometary outburst in late July, Caesar's Comet is one of only five comets known to have had a negative absolute magnitude (for a comet, this refers to the apparent magnitude if the comet had been observed at a distance of 1 AU from both the Earth and the Sun) and may have been the brightest daylight comet in recorded history.[verification needed]
In the absence of accurate contemporary observations (or later observations confirming an orbit that predicts the earlier appearance), calculation of the comet's orbit is problematic and a parabolic orbit is conventionally assumed. (In the 1800s a possible match with the Great Comet of 1680 was speculated which would give it a period of about 575 years. This has not been confirmed because the later observations are similarly insufficiently accurate.) The parabolic orbital solution estimates that the comet would now be more than 800 AU (120 billion km) from the Sun. At that distance, the Sun provides less light than the full Moon provides to Earth.
Caesar's Comet was known to ancient writers as the Sidus Iulium ("Julian Star") or Caesaris astrum ("Star of Julius Caesar"). The bright, daylight-visible comet appeared suddenly during the festival known as the Ludi Victoriae Caesaris—for which the 44 BC iteration was long considered to have been held in the month of September (a conclusion drawn by Edmund Halley). The dating has recently been revised to a July occurrence in the same year, some four months after the assassination of Julius Caesar, as well as Caesar's own birth month. According to Suetonius, as celebrations were getting underway, "a comet shone for seven successive days, rising about the eleventh hour, and was believed to be the soul of Caesar."
The Comet became a powerful symbol in the political propaganda that launched the career of Caesar's great-nephew (and adoptive son) Augustus. The Temple of Divus Iulius (Temple of the Deified Julius) was built (42 BC) and dedicated (29 BC) by Augustus for purposes of fostering a "cult of the comet". (It was also known as the "Temple of the Comet Star".) At the back of the temple a huge image of Caesar was erected and, according to Ovid, a flaming comet was affixed to its forehead:
To make that soul a star that burns forever
Above the Forum and the gates of Rome.
Tracing the coinage from 44 BC through the developing rule of Augustus reveals the changing relationship of Julius Caesar to the Sidus Iulium. Robert Gurval notes that the shifting status of Caesar's Comet in the coinage follows a definite pattern. Representations of the deified Julius Caesar as a star appeared relatively quickly, occurring within several years of his death. About twenty years passed, however, before the star completed its transformation into a comet. Starting in 44 BC, a money maker named P. Sepullius Macer created coins with the front displaying Julius Caesar crowned with a wreath and a star behind his head. On the back, Venus, the patron goddess of the Julian family, holds a starred scepter. Gurval maintains that this coin was minted about the time of Caesar's assassination and thus probably would not have originally referred to his deification. As it circulated, however, it would have brought that idea to mind because of Caesar's new cult. Kenneth Scott's older work The Sidus Iulium and the Apotheosis of Caesar contests this by assuming that the comet did indeed spark this series because of similarity to other coins he produced. A series of Roman aurei and denarii minted after this cult began show Mark Antony and a star, which most likely represents his position as Caesar's priest. In later coins likely originating near the end of Octavian's war with Sextus Pompey, the star supplants Caesar's name and face entirely, clearly representing his divinity.