"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. And I beheld, and heard an angel flying through the midst of heaven, saying with a loud voice, Woe, woe, woe, to the inhabiters of the earth by reason of the other voices of the trumpet of the three angels, which are yet to sound!"
The fourth trumpet brings about a series of bizarre eclipses and astronomical events which are difficult to explain this side of the Tribulation. Man has long been fascinated by the lights of the heavens. Throughout the ages, the heavenly bodies have been the objects of man's worship. However, in the end, they will be used by the God Who made them for the purposes of His glory.
No part of the earth is unaffected by night and day. The Psalmist said, "Day unto day uttereth speech, and night unto night sheweth knowledge. There is no speech nor language, where their voice is not heard (Psalm 19:2-3)." In every corner of the globe, these astronomical wonders will be witnesses of God's wrath and power.
God's grace is displayed in the angel's message as he pleads with the inhabitants of the world to heed the imminent judgments. The Lord makes a distinction between the children of darkness and the children of light by using the term inhabiters of the earth. In Revelation, this title is used exclusively to identify the devil's children versus the children of God. One does not have to worship Satan openly in order to have this title. He simply has to be alienated from Christ through unbelief.