When Lexell's Comet passed by the earth, it was -- and remains -- the closest approach by a comet in recorded history.
Call the average distance between Earth and the Moon (about 240,000 miles) 1 LD. Within how many LDs did Lexell's Comet pass? Answers within 15% in either direction accepted.
5.65 LDs (1.36 million miles) - accept anything from 4.8 to 6.5 LDs (July 1, 1770)