Comet Scare of 20 May 1773: A Terrifying Prediction

The comet scare of 20 May 1773 was not the first. Comets and the idea that one would hit the earth and destroy it, had long been a concern of humans. Seventeenth-century mathematician Jacob (also called James or Jacques) Bernoulli predicted the famous comet of 1680. It was called “Kirch’s Comet,” the “Great Comet of 1680,” or “Newton’s Comet.” Bernoulli thought it would return and cause a terrible fracas on 17 March 1719. He was mistaken. The 1680 comet — the first comet discovered by telescope but reputedly so bright it was easily visible at daytime — was not “an infallible sign of the wrath of heaven,”[1] and the world did not end despite Bernoulli’s prediction.

Comet scare - Jacob Bernouilli

Jacob Bernoulli. Courtesy of Wikipedia.

Bernoulli was not the only person to believe a comet would bring the world to an end. In 1773, Joseph Jérôme Lefrançois de Lalande, a French astronomer and one of the ablest mathematicians of the times, wrote a paper titled “Reflections on those Comets which Can Approach the Earth.” Lalande read his paper at the Academy of Sciences, and word leaked out that he had supposedly predicted the end of the world, as the result of a collision between a comet and the earth.

Lalande had predicted no such thing, and despite it being blatantly untrue, rumors swiftly became unmanageable with people reporting it as “definite news.” Further Parisians assigned a date for the cataclysmic event. Thus, the comet scare of 20 May 1773 was born.

Lalande decided he must do something about the rumor. He hoped that he could put a stop to false rumors by running an advertisement in the Gazette de France that appeared on 7 May 1773. It read:

“[Barely had] M. Lalande … time to read his memoir upon comets which may approach the earth and cause changes in their motions; but he would observe that it is impossible to assign the epochs of such events. The next comet whose return is expected is the one which should return in eighteen years; but it is not one of those which can hurt the earth.”[2]

Lalande’s denial went unheeded. Despite predicting no imminent demise of Paris, concerned Parisians rushed daily to his office with anxious inquiries about their fate worried over the supposed comet scare that was to come. In fact, a number of pious people, of “whom a contemporary journal made the very rude remark that ‘they were as ignorant as they were imbecile,’ begged the Archbishop of Paris to appoint a forty days’ prayer to avert the threatened danger.”[3] The Archbishop was all set to comply but then Academy members learned about it. They were so outraged they notified him that “he would bring ridicule upon himself and upon science if he did so.”[4]

François-Marie Arouet, known by his nom de plume Voltaire, reported he also received many letters from concerned Parisians believing the comet was poised to destroy Paris. He wrote a letter dated 17 May 1773 and noted in it that “Parisians will not desert their city on the 20th of May; they will make songs, and play the comet and the end of the world on the stage of the Opera House.”[5] Unfortunately for Voltaire, some Parisians did desert Paris and fled to nearby countries hoping to find safety and comfort there.

Top to Bottom and Left to Right: Joseph Jérôme Lefrançois de Lalande, Voltaire, Charles Messier, and Dominique François Jean Arago, Public Domain

Top to bottom and left to right: Joseph Jérôme Lefrançois de Lalande, Voltaire, Charles Messier, and Dominique François Jean Arago. Public domain.

It probably did not help that a few months prior, in February, a gentleman claiming to be Avant-Coureur (meaning front runner) appeared. He declared he was born in the heavens and asserted he was a prophet of God. Moreover, he began preaching “repentance and amendment.” He alleged Paris would be destroyed on 15 May and also stated:

“[A comet would appear in April] if it had one tail, an earthquake would be the instrument of its destruction; if it had two, there would be a fire-rain; but if twenty parts of the inhabitants of that city changed their way of living, God would forgive the rest, and keep it safe for thirty years more.”[6]

For the terrified and ignorant who remained in Paris, the fear inspired by the comet scare, resulted in charlatans and speculators taking advantage of them. The credulous were somehow persuaded by them that the clergy had granted them special intercession and that they had “obtained the privilege of dispensing a number of tickets for seats to Paradise.”[7] Of course, these seats were sold for very high prices.

Despite all the conjecture and credulity of Parisians no comet hit the city. In fact, no comet was seen in the sky in May, June, July, August, or September. A comet did appear in October that was later called C/1773 T1. It was first observed on 17 October 1773 by Charles Messier, a French astronomer noted for creating an astronomical catalog, known as “Messier objects”. It consisted of nebulae and star clusters that helped comet hunters distinguish between permanent and transient objects in the sky.

Unfortunately, Parisians did not learn their lesson. A similar comet scare occurred in 1832 when it was announced that the comet of 1826 (a periodic comet named Biela’s Comet) would return in 1832. At the time, a report claimed the comet would nearly intersect with earth. Apparently, no one paid attention to the word nearly, and rumors flew that the comet was going to collide with earth. Authorities worried the same panic that gripped Paris in 1773 would occur if the Academy of Sciences did not immediately apply a “prompt remedy.”

Comet Scare: Biela's Comet in February 1846, After it Split into Two Pieces. Courtesy of Wikipedia

Biela’s Comet in February 1846, after it split into two pieces. Courtesy of Wikipedia.

This time they took immediate action. One member of the Academy, Dominique François Jean Arago, published a treatise on comets in the Annuaire. In this 1832 document Arago showed the path of the comet remarking:

“[It was to] proceed a little within [the earth’s] … orbit, and … that on the 29th October 1832, a portion of the earth’s orbit might be included within the nebulosity of the comet; but that the earth would not arrive at the same point of its orbit till the morning of the 30th of November, or more than month afterwards; and consequently … the earth would be more than twenty million … French leagues (or fifty million … British miles) distant from the comet.” Thus, a second panic was averted.”[8]


  • [1] -, in Bath Chronicle and Weekly Gazette, 08 July 1773, p. 5.
  • [2] The Eclectic Magazine of Foreign Literature, Science, and Art, Vol. 98, 1882, p. 838.
  • [3] Ibid.
  • [4] Ibid.
  • [5] Ibid., p. 839.
  • [6] “Paris, May 20,” in The Maryland Gazette, 19 August 1773, p. 1.
  • [7] The Eclectic Magazine of Foreign Literature, Science, and Art, p. 839.
  • [8] Dick, Thomas, The Christian Philosopher, 1850, p. 156.

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