Celestial object last seen in 1986 (7,5)
I believe the answer is:
halleys comet
(Other definitions for halleys comet that I've seen before include "Visitor from outer space every 76 years" , "Visitor last seen 15 years ago" , "It appears every 76 years" , "Body last seen in 1986" , "Periodic visitor to Earth's skies" .)