Revelation 6:12-14 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.
Hi all
Christ comes with the "clouds of heaven" which I believe means he brings with him heavenly matter (space debris). This falls to earth (meteorites and meteors) in verse 13. This leads to a darkening of the earth's sky as in a nuclear winter or after a volcanic eruption making the moonlight red and the sunlight granular.
Then, the sky seems to rip and tear which seems to be what the Greek for "departed" is. Maybe the sky clears and the darkness rolls together like a scroll being closed, to reveal Christ in the celestial heavens.
Revelation 6:16 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:
When the darkened sky rolls together, it reveals the frightening sight of Christ in his glory. That is when the wicked people run to caves to hide from Christ's face or parousia or appearing.