Then shall appear the sign of the Son of man in heaven — It seems a little before he himself descends. The sun, moon, and stars being extinguished, (probably not those of our system only,) the sign of the Son of man (perhaps the cross) will appear in the glory of the Lord.
Related Commentaries of Matthew 24:30
Matthew 24:30
30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.