Halley's Comet, or Comet Halley as it is sometimes referred to, has been flying around the solar system every 76 years ever since astronomers could be bothered looking, but now a heated debate has sprung up in my own mind about the future of the comet - or rather, its pronunciation!
Comet Halley - named after English astronomer Edmund Halley, who fathomed its trajectory in 1705 - is regularly pronounced /ˈheɪli/, rhyming with daily, or /ˈhæli/, rhyming with valley. One of Edmond Halley's biographers, a Mr. Colin Ronan, preferred /ˈhɔːli/ (HAW-lee, similar to holly). Spellings of Halley's name during the man's own lifetime included Hailey, Haley, Hayley, Halley, Hawley, and Hawly, so its pronunciation is uncertain, but present-day people with the same surname seem to prefer the one that rhymes with "valley".
Sir Isaac Newton, who was a friend of Halley's, could have done us all a favor if he had realized the two objects he observed in 1680 and 1681 were one and the same, because then the comet would then have been known as Newton's Comet, with no such pronunciation problems.
As it was, he just wasn't quite clever enough.