Astronomical event
'astronomical event' is the definition.
(eclipse is a type of astronomical event)
This is all the clue.
(Other definitions for eclipse that I've seen before include "Total - - of the sun" , "Decline" , "Heavenly phenomenon" , "When light's dropped" , "Throw into obscurity, perhaps the sun" .)
'astronomical event' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nova that I've seen before include "Star showing a sudden temporary increase in brightness" , "Kind of star" , "Faint star that suddenly flares into brightness and then fades again" , "Star briefly brightening" , "Star that suddenly increases in brightness" .)