The beacons referred to in the title of the piece are pulsars. Pulsars are incredibly dense stars whose spinning motion emits a pulsing radiation that can be detected over great distances. These extraordinary objects can serve as reference points should one find himself wandering through the universe. Pulsars were indicated on a map sent with the Pioneer 10, the first interstellar spacecraft. This map is intended to explain, to whomever the spacecraft might come in contact with, how to find the planet Earth. The beacons are represented musically in the piece by various types of pulsation.
The text to Beacons of the Sky was written by the composer:
From dawn to eternity,
traveler's advisory,
measuring all history,
beacons of the sky.