Brethren, these few years many pastors, Christian leaders, etc. are crediting every unusual heavenly happening (e.g 4 blood moons by John Hagee, solar eclipse during Jewish feasts, stars positions, asteroids near earth, etc.) to Luke 21:11b "and there will be fearful sights and great signs from heaven." and with all their false prophecies down the drain. These false teachers are destroying Christian's faith in the Bible, His words and in end time prophecies.
We must interpret bible verses, parables, teachings, etc. from the complete council of God otherwise we may fall into heresies. With end time prophecies, all events up to Rapture must be synchronized with Mat 24 (or Mark 13) and the 7 Seals, which are in chronological order.
1st Seal - False christs
Luke 21:8-11a And He said: "Take heed that you not be deceived. For many will come in My name, saying, 'I am He,' and, 'The time has drawn near.' Therefore do not go after them.
This event of deceptions by false christs is the same as Mat 24:4-5 and Mark 13:5-6 and the first Seal in Rev 6:1-2 (Note:- 2nd and 3rd seals were also opened during this period.)
4th Seal - World War 3
But when you hear of wars and commotions, do not be terrified; for these things must come to pass first, but the end will not come immediately." Then He said to them, "Nation will rise against nation, and kingdom against kingdom. And there will be great earthquakes in various places, and famines and pestilences;"
The above Scriptures are the same World War 3 in the Period of Sorrows in Mat 24:7-8 and Mark 13:7-8 and the 4th Seal in Rev 6:7-8.
5th Seal - Period of Tribulation
The fearful sights and great signs can only occur after Luke 21:12-19, the period of Sorrows/Tribulations where Christians will be persecuted, imprisoned, tortured, killed and martyred. This period corresponds to Mat 24:9-28, Mark 13:9-23 and 5th Seal in Rev 6:9-11.
(Note:- in Luke 21:20-24, our Lord revealed that Jerusalem will be conquered by Gentiles during WW3)
Fearful sights and Great signs
Luke 21:11b "and there will be fearful sights and great signs from heaven."
Luke 21:12 "But before all these things, they will lay their hands on you and persecute you, delivering you up to the synagogues and prisons. You will be brought before kings and rulers for My name's sake."
Since the persecution of Christians in Luke 21:12-19 (5th Seal) will be before the fearful sights and great signs, then these fearful sights must be in the 6th Seal.
6th Seal - Heaven blackened
Luke 21:25-27 "And there will be signs in the sun, in the moon, and in the stars; and on the earth distress of nations, with perplexity, the sea and the waves roaring; men's hearts failing them from fear and the expectation of those things which are coming on the earth, for the powers of heaven will be shaken. Then they will see the Son of Man coming in a cloud with power and great glory."
Brethren, the fearful sights will be the great heavenly blackout, and the great signs will be the coming of our Lord Jesus with His heavenly hosts.
Luke 21:11b "and there will be fearful sights (great heavenly blackout) and great signs from heaven (Jesus coming with His heavenly hosts)."
2Pet 2:1 But there were also false prophets among the people, even as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Lord who bought them, [and] bring on themselves swift destruction.