Step still to come (one reading among others)

Luke — signs in the heavenly bodies and distress of nations

**Artist’s impression** The Opening of the Sixth Seal, artist’s impression by Francis Danby (c. 1825): people’s terror, a motif parallel to Luke 21:25-26. A scene that has not happened. — Francis Danby (Victoria Art Gallery, Bath), Wikimedia Commons · Domaine public

? Not yet happened, no date

See the full entry: sources, objections, answers

In short

The announcement. Jesus, in the Gospel of Luke, announces signs in the sun, the moon and the stars, the anguish of nations at the roaring of the sea, people fainting with fear, then the coming of the Son of Man in a cloud.

What happened. This has not happened yet. In Luke, these signs come after “the times of the Gentiles” and just before the coming of the Son of Man.

What is still debated. Luke shows a longer transition than Matthew's compressed account, and the length of this transition is not specified.

The text (World English Bible)

“There will be signs in the sun, moon, and stars; and on the earth anxiety of nations, in perplexity for the roaring of the sea and the waves; men fainting for fear and for expectation of the things which are coming on the world, for the powers of the heavens will be shaken. Then they will see the Son of Man coming in a cloud with power and great glory. But when these things begin to happen, look up and lift up your heads, because your redemption is near.”
Luke 21:25-28