A person who studies, observes, or writes about comets; a specialist in cometology.
Constructed from 'comet' plus '-grapher' (one who writes or records), following the pattern of 'biographer' and 'photographer'. A modern technical term for comet specialists.
Creating agent nouns with '-grapher' is how we name specialists—a cometographer is to comets what a biographer is to lives, though you'd more likely hear the term 'cometologist' in actual practice.
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