a comet with a period averaging 76 years. In this century it was visible to terrestrial observers just before and after reaching perihelion in 1910 and again in 1986.
Origin: named after Edmund Halley, who first predicted its return
Pronunciation note: The common pronunciation for both the comet and the astronomer after whom it is named is/ˈhæli/Show Spelled Pronunciation[hal-ee]Show IPA. This is the pronunciation usually recommended by astronomers. However, several variant spellings of the name, including Hailey, Haley, and Hawley, were used interchangeably during the astronomer's own time, a period when spellings even of proper names were not yet fixed, and corresponding pronunciations have survived. The pronunciation/ˈheɪli/[hey-lee]in particular remains associated with Halley's comet; it is less likely to be heard as a pronunciation of Edmund Halley.
[hal-eez or, sometimes, hey-leez] 
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