Shortly before his arrest in Jerusalem, as Mark tells the story, Jesus made a prediction: after a period of severe tribulation the sun and moon would be darkened, the stars would fall from heaven, the powers of heaven would be shaken, people would see “the Son of Man coming in clouds with great power and glory”, and the Son of Man would send out his angels to “gather his elect from the four winds, from the ends of the earth to the ends of heaven” (Mk. 13:24-27).
The “tribulation” is a reference to the sequence of events described in Mark 13:3-23, which can reasonably be understood as a prediction of war against Israel and the destruction of Jerusalem and the temple. Jesus is telling his disciples what they should expect and how they should behave as the crisis unfolds, culminating in a warning about false Christs and false prophets.
But at verse 24 the language shifts gear; we enter a vividly apocalyptic mode of discourse, and the question arises whether we have moved beyond the stuff of ordinary history. It sounds as though Jesus is now talking about disruption on a cosmic scale.