Related Clues:

• See 54-Across
• Interminable time
• Junior, for one
• 2001, e.g.
• A long time
• Birthday-to-birthday span
• A billion years
• Many ages
• 3.26 light-years
• 2000, for one
• With 28-Across, late December
• Time period
• Sentence unit
• Forever, seemingly
• Many a millennia