My best guess it that it probably did not happen - literally. However that the story and the examples given contain an important cultural element that goes back to the time before recorded history. Some people like Erich von Daniken want to put space aliens into the story here; but I don't think that's needed or warranted. We still have an amazing story that possibly links all human beings on the planet to a common thread.
Anything beyond the commonality of the story seems to end up being myth, legend or speculation. I'm afraid that's all I've got; a great big question - but a question that
does answer a lot of secular arguments against the veracity and importance of the Bible.
More than a grain - but remember, the story can be completely true without being a record of an historical event. Remember that there was a certain man who went down to Jericho? As it turns out, that "certain man" never actually existed nor did the rest of the characters in the story. And no one who heard the story was required to believe it had literally happened - but we are all admonished to accept the truth of the story and to model the behavior of the Good Samaritan.
The same case can be made for the Parable of Rich Man and Lazarus. This was told as a series of parables and clearly identified as such in the Gospel of Luke. Wee don't have to believe that the poor man Lazarus had lain on the street with dogs licking his sores to believe in the truth of the resurrection and judgment to come.
Jude 1:14-15 is clearly a quote from the Bookk of Enoch
:
"And Enoch also, the seventh from Adam, prophesied of these [men], saying,
Behold, the Lord cometh with ten thousands of his saints, To execute judgment upon all, and to convince all that are ungodly among them of all their ungodly deeds which they have ungodly committed, and of all their hard speeches which ungodly sinners have spoken against him."
Enoch 1:9:
"And
behold! He cometh with ten thousands of His holy ones To execute judgement upon all, And to destroy all the ungodly: And to convict all flesh Of all the works of their ungodliness which they have ungodly committed, And of all the hard things which ungodly sinners have spoken against Him."
1 Peter 3:19-20, though not a quote like Jude's is a specific reference that has convince readers of the Bible from the 100's through today that Peter had Enoch's description in mind:
"By which also he went and preached unto the spirits in prison;
Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.
Enoch 21:
1,2 And I proceeded to where things were chaotic. And I saw there something horrible: I saw neither 3 a heaven above nor a firmly founded earth, but a place chaotic and horrible. And there I saw 4 seven stars of the heaven bound together in it, like great mountains and burning with fire. Then 5 I said: 'For what sin are they bound, and on what account have they been cast in hither?' Then said Uriel, one of the holy angels, who was with me, and was chief over them, and said: 'Enoch, why 6 dost thou ask, and why art thou eager for the truth? These are of the number of the stars of heaven, which have transgressed the commandment of the Lord, and are bound here till ten thousand years, 7 the time entailed by their sins, are consummated.' And from thence I went to another place, which was still more horrible than the former, and I saw a horrible thing: a great fire there which burnt and blazed, and the place was cleft as far as the abyss, being full of great descending columns of 8 fire: neither its extent or magnitude could I see, nor could I conjecture. Then I said: 'How 9 fearful is the place and how terrible to look upon!' Then Uriel answered me, one of the holy angels who was with me, and said unto me: 'Enoch, why hast thou such fear and affright?' And 10 I answered: 'Because of this fearful place, and because of the spectacle of the pain.' And he said unto me: 'This place is the prison of the angels, and here they will be imprisoned for ever.'