<Tr> <Th> Albedo </Th> <Td> 0.04 </Td> </Tr> <Tr> <Th> Apparent magnitude </Th> <Td> 28.2 (in 2003) </Td> </Tr> <P> Halley's Comet or Comet Halley, officially designated 1P / Halley, is a short - period comet visible from Earth every 74--79 years . Halley is the only known short - period comet that is regularly visible to the naked eye from Earth, and the only naked - eye comet that might appear twice in a human lifetime . Halley last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061 . </P> <P> Halley's returns to the inner Solar System have been observed and recorded by astronomers since at least 240 BC . Clear records of the comet's appearances were made by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object at the time . The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named . </P>

When was the last time halley's comet passed earth