The most intense supernova in recorded history occurred in the year 1006 A.D., when a massive supernova occurred on April 30 and was bright enough to be recorded over a period of several months as it gradually dimmed. Today astronomers have been able to pinpoint the site of the supernova, formally designated SN 1006, in the Wolf (Lupus) constellation, over 7000 light-years away.
- Observations at the Time -
Most civilizations in the northern hemisphere which left written records during the 11th century made at least some reference to the supernova in those records, including Egypt, the Middle East, Europe, and China. However, it is the Chinese and Arabic astronomical records which are the most complete for this time period, and they are the ones with the most specific information.
In Egypt, Ali ibn Ridwan compared the supernova with the size of Venus on the horizon, but noted that it was far brighter, somewhere between the average star and the Earth's own Moon. Benedictine monks in Switzerland collaborate Ridwan's account that the light appeared to the south and was bright for a period of about three months. Exactly how bright is uncertain, but the accounts indicate that it could be spotted in the sky even in daylight.
Chinese records also noted the appearance of the star. Astrologers there were initially perplexed as to what it might mean; not realizing (nor did anyone else, for that matter) what a supernova actually was, the emperor's astrologers suggested that perhaps it was an indication of coming economic good fortune.
After about three months, the records indicate that the supernova diminished, but was still visible at night for over a year.
- What Really Happened (We Think) -
In the 1960s, astronomers identified a radio source in the Wolf constellation, near a star called Beta Lupi. This radio source was previously designated by the bland descriptor PKS 1459-41. The source was identified as a supernova remnant, the debris ejected from a massive explosion. Cross-referencing the old astrological records, they confirmed that this source was connected to a thousand-year-old supernova, and gave it a new designation to reflect that: SN 1006, after the year it was noticed on Earth.
SN 1006, or PKS 1459-41 as it was previously known, is over 7000 light-years away from the Earth. This means, as hard as it may be to wrap one's head around it, that the supernova actually occurred not one thousand years ago but eight thousand years ago; the light from the supernova then spent 7000 years travelling to Earth before it was finally noticed by the astrologers in 1006. At such a distance, while the light show would have been spectacular, Earth was not in substantial danger of exposure to radiation. Supernovae much closer to Earth, and of similar intensity, could put us at risk if they were to occur today, especially if we were in the path of a gamma ray burst.