“Then the fifth angel blew his trumpet, and I saw a star that had fallen to earth from the sky, and he was given the key to the shaft of the bottomless pit. When he opened it, smoke poured out as though from a huge furnace, and the sunlight and air turned dark from the smoke.” Revelation 9:1-2
When the fifth angel sounded his trumpet, John saw a star from heaven that had fallen to the earth. In his visions, the apostle had already seen several heavenly bodies plunge to earth unlike them; however, this star was not an inanimate piece of celestial matter, but an angelic being. That he was said to have fallen to the earth suggests that this is a reference to Satan—the leader of all the fallen angels (cf. Isaiah 14:12–15; Ezekiel 28:12–16; Luke 10:18). The fall of Satan described in 9:1 is not his original rebellion. Though he and the angels who fell with him were banished from heaven, Satan retains access to God’s presence, where he constantly accuses believers. During the tribulation he and his demon hosts will unsuccessfully battle Michael and the holy angels. As a result of their defeat, they will be permanently cast down to the earth (12:7–9). Satan will then seek to marshal all of his demonic hosts—those already on earth, those cast to earth with him, and those incarcerated in the bottomless pit (literally “the pit of the abyss”). Abussos (“bottomless”) appears seven times in Revelation, always in reference to the abode of incarcerated demons (9:2, 11; 11:7; 17:8). Satan himself will be held prisoner there during the millennium, chained and locked up with the other demonic prisoners (20:1, 3). After Satan received the key to the abyss from its keeper, Jesus Christ (1:18), he opened the bottomless pit and released its inmates. When the abyss opened, smoke arose like the smoke of a great furnace. “Smoke” in Revelation may refer to holy things (8:4; 15:8), but is usually associated with judgment (9:17–18; 14:11; 18:9, 18; 19:3). Such a vast volume of smoke issued from the abyss that the sun and the air were darkened by it. The smoke polluting the sky symbolizes the corruption of hell belched forth from the abyss to pollute the world.