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Astronomers Investigating Unknown Object That Hit the Earth In 773 AD 84

Posted by samzenpus
from the what-could-it-be dept.
KentuckyFC writes "In November 2012, a group of Japanese scientists discovered that the concentration of carbon-14 in Japanese cedar trees suddenly rose between 774 AD and 775 AD. Others have since found similar evidence and narrowed the date to 773 AD. Astronomers think this stuff must have come from space so now the quest is on to find the extraterrestrial culprit. Carbon-14 is continually generated in the atmosphere by cosmic rays hitting nitrogen atoms. But because carbon-14 is radioactive, it naturally decays back into nitrogen with a half-life of about 5700 years. This constant process of production and decay leaves the amount of carbon-14 in the atmosphere relatively constant at about one part in a trillion will be carbon-14. One possible reason for the increase is that the Sun belched a superflare our way, engulfing the planet in huge cloud of high energy protons. Recent calculations suggest this could happen once every 3000 years and so seems unlikely. Another possibility is a nearby supernova, which bathed the entire Solar System in additional cosmic rays. However, astronomers cannot see any likely candidates nearby and there are no historical observations of a supernova from that time. Yet another possibility is that a comet may have hit the Earth, dumping the extra carbon-14 in the atmosphere. But astronomers have ruled that out on the basis that a comet carrying enough carbon-14 must have been over 100 km in diameter and would surely have left other evidence such as an impact crater. So for the moment, astronomers are stumped."
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Astronomers Investigating Unknown Object That Hit the Earth In 773 AD

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  • Some Background (Score:4, Interesting)

    by Anonymous Coward on Sunday February 02, 2014 @10:33AM (#46133761)
  • Re:Why unlikely? (Score:5, Interesting)

    by ShanghaiBill (739463) on Sunday February 02, 2014 @12:24PM (#46134347)

    If it is as frequent as every 1/3000 years, there definitely be some evidence of it.

    But there is evidence: The elevated C14 in the tree rings from 773AD. What other evidence would there be? A lack of historical records is not strong evidence again the solar flare theory, since Europe was in the dark ages and there were few literate people and few records survive from that period. China was thriving and prosperous under the Tang Dynasty, but it may have happened during the night in China, or even on a cloudy, overcast day, which is common in eastern China.

  • Re:Why unlikely? (Score:5, Interesting)

    by Deadstick (535032) on Sunday February 02, 2014 @12:40PM (#46134409)

    A lack of historical records is not strong evidence again the solar flare theory, since Europe was in the dark ages and there were few literate people and few records survive from that period. China was thriving and prosperous under the Tang Dynasty, but it may have happened during the night in China, or even on a cloudy, overcast day, which is common in eastern China.

    Indeed. The Chinese, and possibly Arabs, Japanese and Anasazi Indians, noted the supernova of 1054 CE that made the Crab Nebula; Europe missed it altogether. Time of day was not an issue for that event, because it lasted a couple of years.

    But anyway, it's only TFP that alludes to a lack of historical records: TFA cites two.

  • Yeah? Well... (Score:4, Interesting)

    by Jawnn (445279) on Sunday February 02, 2014 @02:26PM (#46134943)
    FTFA...

    One possible reason for the increase is that the Sun belched a superflare our way, engulfing the planet in huge cloud of high energy protons.

    ...and it could just be God, testing our faith. We learn from presentations at The Creation Museum that God does this all the time, putting riddles into nature to show us that we aren't all smart and sciency like we think we are. He could totally make a giant space gun that shoots high-energy protons at certain places in the earth to make it look like something happened a long time ago, just like he made it look like the dinosaurs lived way before Adam and Eve.

  • Re:Why unlikely? (Score:5, Interesting)

    by Troed (102527) on Sunday February 02, 2014 @03:22PM (#46135231) Homepage Journal

    2000 years of global extreme climate events from historical records: http://www.breadandbutterscien... [breadandbu...cience.com]

    773 A.D. In 773 A.D., a severe drought struck Shensi (now Shaanxi province) in central China at Sian.

    In 773 A.D., there was a great drought in Shensi province in China.

    774 A.D. In Scotland, there was a severe famine with a plague.

    Winter of 774 / 775 A.D. In the year 675, there was the greatest frost in England.
    [This entry was out of chronological order and I believe Short was referencing the year 775 A.D.]

    775 A.D. In England, there was a drought with excessive heat, after a great frost.

    The winter was so hard that the Euxine Sea (Black Sea) was quite frozen over. The ice was 30 foot or
    cubits thick. People could walk 50 or 100 leagues (150 to 300 miles, 240 to 480 kilometers) on the ice
    from the Danube River to the Euphrates River. On the ice fell 30 cubits deep of snow. When the ice
    broke, it appeared like great mountains on the sea, which demolished and carried down whole villages
    standing on the shore. This winter was succeeded by so excessive heat during the summer that all springs
    dried up.72 [The Danube River probably refers to the Danube Delta in Europe, eastern Romania and south
    western Ukraine. The Euphrates River rises in Turkey, passes through Syria, and joins with the Tigris
    River in southeastern Iraq to form the Shatt al Arab, which empties into the Persian Gulf.]

    In the year 775, “Snow fell, and lay 30 Cubits on a Level.”

    [In Byzantium], the summer was hot and all the wells dried up.62 [Byzantium at this time included
    Turkey, and the western part of the Balkan peninsula.]

    In 775 A.D. during the period 1-30 August, floods struck Chekiang (now Zhejiang province) on the east
    coast of China at Hangchow.

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