Revelation 8:12 The fourth angel sounded his trumpet, and a third of the sun was struck, a third of the moon, and a third of the stars, so that a third of them turned dark. A third of the day was without light, and also a third of the night.
The fourth trumpet effects the sun, moon, and stars, reducing their light by one third. Darkness is a common symbol of terror and the end of the world, the reduction of light will increase terror, and make food production less effective. Like the other trumpets, this unnatural darkness recalls the plague of darkness in Exodus 10:21-23.
Darkness is often associated with God’s judgment in the Old Testament. Amos 5:18 describes the Day of the Lord as “darkness, not light” and Joel 2:2 calls is a day of “darkness and gloom, a day of clouds and blackness.” Isaiah 13:10 describes the Day of the Lord for Babylon as a time when “the stars of heaven and their constellations will not show their light. The rising sun will be darkened and the moon will not give its light.” Similarly, tn the Olivet Discourse Jesus says just prior to the coming of the Son of Man, “the sun will be darkened, and the moon will not give its light, and the stars will be falling from heaven, and the powers in the heavens will be shaken.” (Mark 13:24-25).
This darkness is unnatural, listed among the “evil signs” in the ancient world. For example, Lucan describes the moon growing dim and the sun turning dark, “forcing mankind to despair of daylight” (1.536-43). David Aune suggests the unnatural darkness in Revelation 8:12 is an allusion to the eruption of Mount Vesuvius, citing the eyewitness report of Pliny the Younger (Ep. 6.16.17; 6.20.15; Aune 2:522).
Unnatural darkness also appears in Second Temple period apocalyptic texts. In the Animal Apocalypse, when the Lord of the sheep came upon enemies of the sheep in wrath, “all who saw him fled and fell all into darkness, from before his face” (1 Enoch 90.15).
1 Enoch 62.9–10 On that day, all the kings, the governors, the high officials, and those who rule the earth shall fall down before him on their faces, and worship and raise their hopes in that Son of Man; they shall beg and plead for mercy at his feet. But the Lord of the Spirits himself will cause them to be frantic, so that they shall rush and depart from his presence. Their faces shall be filled with shame, and their countenances shall be crowned with darkness.
Ezekiel the Tragedian 1.141–146 And I shall make the heavens bitter; hail and fire shall fall and slay all mortal men, and cause to perish every crop and beast. Darkness I’ll decree for three whole days, and locusts send, who shall the residue of food consume and every blade of grass.
Both these texts are remarkable parallels to the to the unnatural darkness in both the sixth seal (Rev 6:12-17 as well as the fourth trumpet. Ezekiel the Tragedian is retelling the story of the plagues, but notice he has reverse the order of the locust and darkness so that the locust follow the plague of darkness, as in the fourth and fifth trumpets.
In contrast, the absence of darkness is often a sign of salvation. Revelation 21:24-25, the New Jerusalem is described as a place filled with light, “there will be no night there.” In the conclusion to the Animal Apocalypse, “Sin and darkness shall perish forever, and shall no more be seen from that day forevermore” (1 Enoch 92:5). In the Testament of Levi, the messianic figure described as a “new priest” will drive out all darkness.
Testament of Levi 18:4-5 This one will shine forth like the sun in the earth; he shall take away all darkness from under heaven, and there shall be peace in all the earth. The heavens shall greatly rejoice in his days and the earth shall be glad; the clouds will be filled with joy and the knowledge of the Lord will be poured out on the earth like the water of the seas.
What is it that reduces the light? It is possible that this is the combined effect of all the fire that has been started in the first three trumpets, all of the smoke and pollution have created a cloud cover that reduces light by one third. But the New Testament associates darkness with demonic activity. The fourth trumpet anticipate demonic activity which increases in intensity in the fifth and sixth trumpets. Greg Beale suggest this darkness is a transition to more demonic in the fifth and sixth seal (Beale, 483).