Stars

Stars were a new feature added in Update 0.7.3, along with the Sun and Moon. Together with the moon, the night sky also consists of stars. In current versions, the stars appear as bright points, and the starfield rotates as the night progresses.

Purpose
They are meant to represent the stars one would normally see at night in real life.

Trivia

 * Night time lasts 7 minutes, plus 1.5 minutes each of sunrising and sunsetting.