Planetary Society: June 1178 lunar impact?

The Night the Moon Split in Two -
What really happened one night in June, 1178.

by Melanie Melton

April 20, 2001

A graduate student at the University of Arizona claims that a medieval eyewitness account of a lunar impact may not have had anything to do with the moon at all.

Usually, the moon is a familiar sight in our skies. Its mottled gray appearance and reliably changing phases have been a comforting presence to those on Earth throughout the centuries.

However, in the early evening of June 18, 1178, witnesses who observed the young crescent moon were anything but comforted by what they saw.

The following account was recorded by the English monk, Gervase of Canterbury:

[On the evening of June 18, 1178] after sunset when the moon had first become visible a marvelous phenomenon was witnessed by some five or more men...Now there was a bright new moon...its horns were tilted toward the east; and suddenly the upper horn split in two. From the midpoint of the division a flaming torch sprang up, spewing out, over a considerable distance, fire, hot coals, and sparks. Meanwhile the body of the moon which was below writhed, as it were, in anxiety...the moon throbbed like a wounded snake. Afterwards it resumed its proper state. This phenomenon was repeated a dozen times or more, the flame assuming various twisting shapes at random...Then after these transformations the moon from horn to horn...took on a blackish appearance. The present writer was given this report by men who saw it with their own eyes, and are prepared to stake their honour on an oath that they have made no addition or falsification in the above narrative.

This strange account, recently rediscovered in 1972, has been the cause of much interest among astronomers and others studying lunar features as well as Near Earth Objects.

In 1976, James Hartung published a report suggesting that the men of 1178 witnessed a meteor impact on the Moon that created the 22-kilometer (14-mile) crater Giordano Bruno. Others believe that the men witnessed an Earthly event, an exploding meteor that just happened to line up with their view of the Moon.

This week, Paul Withers of the University of Arizona's Lunar and Planetary Laboratory added his support to the Earthly "exploding meteor" theory.

According to Withers, any lunar impact that would have formed a 22-kilometer crater (like the Giordano Bruno crater) would have thrown up as much as ten million tons of rocks, dust and debris. Much of that debris would have escaped the Moon's gravity and ended up falling to Earth.

If the men of 1178 had witnessed the formation of the Giordano Bruno crater on that June night, they should have also witnessed an intense meteor shower the following nights. After such an explosion, Earth would have been inundated with tons of debris, resulted in a blizzard-like meteor storm. Withers calculated that our planet would have been bombarded by up to 50,000 meteors an hour for an entire week.

Yet, no one recorded a spectacular meteor shower that month. Or, even a mildly interesting one for that matter. Withers examined historical accounts of that period from around the world, including European, Chinese, Arabic, Japanese and Korean. He found no mention of a meteor shower during the appropriate time period.

So what did the men see?

"I think they happened to be at the right place at the right time to look up in the sky and see a meteor that was directly in front of the moon, coming straight towards them," Withers said. "And, it was a pretty spectacular meteor that burst into flames in the Earth's atmosphere - fizzling, bubbling, and spluttering. If you were in the right one-to-two kilometer patch on Earth's surface, you'd get the perfect geometry. That would explain why only five people are recorded to have seen it."

Wither's findings also agree with a scientific paper from 1977 which strongly supports the exploding meteor theory.

Whether the mysterious event was a meteor impacting the Moon, or exploding in Earth's atmosphere, there were five men in 1178 England who observed quite a sight.

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04.20.01

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