There's no doubt this is a sign in the Heavens. When the gold firmament was broken, things changed in viewing the Heavens. The word for the Moon in (Akkadian) Babylonian is Su'en (SIN). The blood reference is for what is coming to earth in judgment.

The sun being darkened and the moon turning to blood is the opening of the 6th seal.

From biblegateway.com Revelation 6:12 And I beheld when he had opened the sixth seal, and, lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood;
13 And the stars of heaven fell unto the earth, even as a fig tree casteth her untimely figs, when she is shaken of a mighty wind.
14 And the heaven departed as a scroll when it is rolled together; and every mountain and island were moved out of their places.
15 And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains;
16 And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb:
17 For the great day of his wrath is come; and who shall be able to stand?

I think the whole universe is going to turn inside out and what is at the center of the this hollow earth as the true morning star is going to shine. It says the stars are going to fall from the Heavens and every mountain and island will be moved from its place.

That which is here after the restrainer is removed is polarizing towards true Heaven or towards true hell as the weeds are separated from the wheat. What is left behind has the gates of hell prevail against them and are subject to the 42 month reign of the antichrist.

From biblegateway.com 2Thessalonians2 Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto him,
2 That ye be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand.
3 Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
4 Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
5 Remember ye not, that, when I was yet with you, I told you these things?
6 And now ye know what withholdeth that he might be revealed in his time.

The 42 month reign of the antichrist is the Great Tribulation. After the rapture, what is left behind will endure the Great Tribulation. The two witnesses will start their mission 3.5 days before the antichrist starts his reign. The two witnesses are killed and then resurrected 3.5 days later at the same time as the 7th trumpet which is when the kingdoms the world are changed to the Kingdom of God. That's when the antichrist, the false prophet, and the fallen world lose their power and are cast away. That which is left and most likely secure in Petra is called up into the clouds with those who were raptured out as the Church.