In Mercury magazine for November-December 1996, page 7 mention is made of the possible detection of Halley's Comet as long ago as 467 BC. With a period of 74-79 years, this means that there may have been at least 32 apparitions of this comet in recorded human history. However, we do not know for certain because there are certainly other comets that can become as bright or brighter than Halley's. There is always new scholarship being done on this comet, and who knows what may be uncovered in old Chinese documents or other sources in the future.
Halley's is classified as a relatively young comet, and since comets loose about 1 percent of their mass each time they enter the inner solar system, Halley's is probably good for about 100 passes. Since it is still going quite strong, it is probably near the beginning of its life, and so probably has not been a 'comet' for much more than the 30 or so apparitions already recorded. According to the Halleys Comet page at Views of the Solar System:
Halley's [HAL-lee] Comet has been know since at least 240 BC and possibly since 1059 BC. Its most famous appearance was in 1066 AD when it was seen right before the Battle of Hastings. It was named after Edmund Halley, who calculated its orbit. He determined that the comets seen in 1531 and 1607 were the same object that followed a 76-year orbit. Unfortunately, Halley died in 1742, never living to see his prediction come true when the comet returned on Christmas Eve 1758.
Copyright 1997 Dr. Sten Odenwald
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