Accoring to Jesus, what will happen just before the sign of the Son of man appears in heaven?

The sun will darken, the moon won't give her light, and the stars will fall from heaven.

The sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken:

And then shall appear the sign of the Son of man in heaven. Matthew 24:29-30