The Holy Bible, Matthew 24:29-30
29 Immediately after the tribulation of those days shall 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:
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.
The Doctrine and Covenants, Section 88:92-93
92 And angels shall fly through the midst of heaven, crying with a loud voice, sounding the trump of God, saying: Prepare ye, prepare ye, O inhabitants of the earth; for the judgment of our God is come. Behold, and lo, the Bridegroom cometh; go ye out to meet him.
93 And immediately there shall appear a great sign in heaven, and all people shall see it together.
The Pearl of Great Price, Joseph Smith—Matthew 1:36
36 And, as I said before, after the tribulation of those days, and the powers of the heavens shall be shaken, 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;
History of the Church, Joseph Smith 5:337
Judah must return, Jerusalem must be rebuilt, and the temple, and water come out from under the temple, and the waters of the Dead Sea be healed. It will take some time to rebuild the walls of the city and the temple, &c.; and all this must be done before the Son of Man will make His appearance. There will be wars and rumors of wars, signs in the heavens above and on the earth beneath, the sun turned into darkness and the moon to blood, earthquakes in divers places, the seas heaving beyond their bounds; then will appear one grand sign of the Son of Man in heaven. But what will the world do? They will say it is a planet, a comet, &c. But the Son of Man will come as the sign of the coming of the Son of Man, which will be as the light of the morning cometh out of the east.
Scriptural Teachings of the Prophet Joseph Smith :280
The editor, as well as some others, “thinks that Joe Smith has his match at last,” because Mr. Redding thinks that he has seen the sign of the Son of Man. But I shall use my right, and declare that, notwithstanding Mr. Redding may have seen a wonderful appearance in the clouds one morning about sunrise (which is nothing very uncommon in the winter season) he has not seen the sign of the Son of Man, as foretold by Jesus; neither has any man, nor will any man, until after the sun shall have been darkened and the moon bathed in blood; for the Lord hath not shown me any such sign; and as the prophet saith, so it must be–”Surely the Lord God will do nothing, but He revealeth His secret unto His servants the prophets.” (see Amos 3:7.) Therefore, hear this, O earth: The Lord will not come to reign over the righteous, in this world, in 1843, nor until everything for the Bridegroom is ready.