Rev. 6:12 When he opened the sixth seal, I looked, and behold, there was a great earthquake, and the sun became black as sackcloth, the full moon became like blood, 13 and the stars of the sky fell to the earth as the fig tree sheds its winter fruit when shaken by a gale.

In chapter eight, Jesus opens the seventh seal. Seven trumpets are distributed, and when the first four trumpets sound, fire mixed with blood falls, more stars fall from the sky, and the moon and sun lose a third of their light. The heavens are shaken.

Rev. 9:1  And the fifth angel blew his trumpet, and I saw a star fallen from heaven to earth, and he was given the key to the shaft of the bottomless pit. 2 He opened the shaft of the bottomless pit, and from the shaft rose smoke like the smoke of a great furnace, and the sun and the air were darkened with the smoke from the shaft. 3 Then from the smoke came locusts on the earth, and they were given power like the power of scorpions of the earth.

Here it becomes clear that the stars are not literal stars. They are Satan and the unfaithful angels who have joined Satan.
The star of the fifth trumpet is Satan himself, who opens the bottomless pit. The bottomless pit is the prison of the fallen angels who united with human women before the Flood. From this union came the Nephilim, hybrid beings of angels and humans. (Genesis chapter 6)
These angels were imprisoned with the Flood.

Jud 1:6 And the angels who did not stay within their own position of authority, but left their proper dwelling, he has kept in eternal chains under gloomy darkness until the judgment of the great day—
2.Pe 2:4 For if God did not spare angels when they sinned, but cast them into hell[1] and committed them to chains[2] of gloomy darkness to be kept until the judgment;

These demons will be released in the last days and will torment people for five months.

Rev.12:7 Now war arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back, 8 but he was defeated, and there was no longer any place for them in heaven. 9 And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole world—he was thrown down to the earth, and his angels were thrown down with him. 

After that, the Horsemen of the Apocalypse are unleashed.
See the website “The Horsemen of the Apocalypse.”

The sounding of the fifth trumpet brings forth something special.