And the fourth angel sounded, and the third part of the sun was smitten, and the third part of the moon, and the third part of the stars; so as the third part of them was darkened, and the day shone not for a third part of it, and the night likewise. (Revelation 8:12)
The sun, moon, and stars have been interpreted to represent the great luminaries of the Western Roman government—its emperors, senators, and consuls. With the removal of its last emperor, in 476, the extinction of Western Rome began (see pp. 21, 22; cf. p. 111). Later, its senate and consulship came to an end.
Shone not for a third part.
The thought seems to be that these bodies would be smitten during one third of the time of their shining, not that one third of the bodies themselves would be smitten so that they would shine with two-thirds brilliance. Thus one third of the day and one third of the night would be dark. Applied to the divisions of the Roman government, the figure may describe the successive extinction of the emperors, senators, and consuls.