Sun-faced Buddha and Moon-faced Buddha are metaphors used in Buddhism. The Sun-faced Buddha lives in the world for a long period – 1800 years or for eternity, the Moon- faced just for one day. 

When we think about our human lives:

There are, as you know, people who live long, like those Sun-faced Buddhas, and there are people whose lives are short, like those Moon-faced Buddhas.

It’s useless to worry.

Baso Dōitsu 709 – 788 recorded in The Blue Cliff Record, a collection of Chan Buddhist koans compiled in 1125