Approximately how often does a spectacularly active, visible comet appear?
A) once a year
B) once every 5 years
C) once every 10 years
D) once every 50 years
E) once every 1,000 years

Question

Quizplus · Accepted Answer

Spectacularly active and visible comets are rare occurrences, but they tend to appear more frequently than once every 50 or 1,000 years. The most recent examples include comet Hale-Bopp (1997) and comet McNaught (2007), which were both visible to the naked eye from Earth. Generally, comets with a visible tail or great brightness appear once every 5-10 years or so.

Approximately How Often Does a Spectacularly Active, Visible Comet Appear