My husband was so delighted with the new-found term perigee-syzygy that he kept repeating it, until the syllables merged into his regular breathing and he fell asleep in his chair.

The compound word means what the vulgar press call a supermoon. A syzygy is the lining-up of the moon, Earth and sun, producing a full moon (or a new moon, which is invisible because only the far side is illuminated).