Related Clues:

• Rare astronomical event
• Once in a lifetime phenomenon?
• Once in it is hardly ever
• Very rarely, if once in one of these
• In which once is very seldom
• Blessing covering misguided mule is a rare occurrence
• If something happens once in it, it's not very often
• Song title words before "You saw me standing alone"
• Very rare occurrence
• Sad and low before noon, a rare occurrence
• Very rare event
• X certificate show one's behind is rare event
• Classic song performed by Sha Na Na on the 'Grease' soundtrack
• Astronomical rarity
• Once in one is a rare event