The Lunar Mystery of 1178: A Mini-Essay

     On the evening of June 18, 1178, five monks in Canterbury witnessed a bizarre occurrence. Shortly after sunset, the bright new moon appeared to split open. As flames and sparks jutted outward from the lunar surface, the moon appeared to writhe uncontrollably. The phenomenon was repeated a dozen times before the sky went dark and the men sat in dazed silence.[1] The entire account was later recorded by one of the monks, Gervase from the monastery of Christ Church, in his Chronicles of Gervase and, since then, it has baffled scientists for centuries. What exactly had the men viewed that Sunday evening? 
     In 1976, Jack Hartung, a scientist at the State University of New York, offered a possible explanation. According to Hartnug, the event depicted in Gervase's Chronicle details the formation of the thirteen-mile-wide lunar crater Giordano Bruno. As the scientist attests, the flames and sparks seen by the monks were the product of space debris colliding with the moon's surface, with the turbulent atmosphere encompassing the moon creating the writhing motion and sunlight reflecting through particles in that atmospheric cloud giving the illusion of flames.[2] Hartung's analysis intrigued the scientific community and, within a few months of his paper's publication, it drew criticism from Glenn Huss and H.H. Nininger, researchers at the American Meteorite Laboratory in Denver. For Huss and Nininger, it seemed improbable that the monks would have been able to see a sixty-mile-long cloud on the moon's surface with the naked eye. Furthermore, the scholars questioned Hartung's atmospheric disturbances and reflected lights. To them, Gervase's text was not the description of a lunar impact, but a meteor passing in front of the moon and burning up in the Earth's atmosphere in a spectacular show of flames and sparks.[3] Just as Hartung's theory had prompted debate, so had Huss and Nininger's rebuke. In 1978, Odile Calame and J. Derral Mulholland used data collected by the Apollo astronauts to support Hartung's claims and asserted that, not only had the debris created the Giordano Bruno cater, but the moon is still vibrating from the force of the impact.[4] In 1994, though, images from the spacecraft Clementine revealed reddish, weathered material along the sloping walls of the crater, which prompted some geologists to question whether Giordano Bruno was truly formed in 1178.[5]
     Currently, Hartung's thesis remains controversial and scientists continue to debate whether or not the event witnessed by Gervase and his peers was a lunar impact, the spectacular destruction of a meteor in the Earth's atmosphere, or something entirely different. 

Works Referenced

Calame, Odile and J. Derral Mulholland. "Lunar Crater Giordano Bruno: A.D. 1178 Impact Observations Consistent with Lunar Ranging Results." Science 199 (1978): 875-877.

Hartung, Jack. "Was the Formation of a 20-km-Diameter Impact Crater on the Moon Observed on June 18, 1178?" Meteoritics 11 (1976): 187-194.

Ingram, Jay. The Barmaid's Brain and Other Strange Tales from Science. New York: MJF Books, 1998.

Nininger, HH and Glenn Huss. "Was the Formation of Lunar Crater Giordano Bruno Witnessed in 1178? Look Again." Meteoritics 12 (1977): 21-25.
____________________
[1] Ingram, 174-176.
[2] Hartung, 190.
[3] Nininger and Huss, 21-25.
[4] Calame and Mulholland, 875-877.
[5] Ingram, 182-183.