Related Clues:

• Geologic time unit
• Lunar or leap, e.g.
• Part of a century
• Oenophile's concern
• A very long period of time
• Time division
• Car registration datum
• Trip around the sun
• It ends with 42-Across
• Reunion number
• Oenologist's concern
• Calendar period
• Astronomical distance
• Wine bottle number
• Almanac span