The disciples asked Jesus, "Look, Master, tell us, when are you coming back and what will be the signs that we may know?"
Christ gave the major signs in Matthew 24:
(1) the destruction of Jerusalem. History shows that in A.D. 70 that sign was passed. Jerusalem was destroyed.
(2) the great tribulation mentioned in verses 21 and 22. Once again we go to history and discover that it is the truth. There was a great period of persecution. The Bible says it would be the worst ever known and if it were not shortened there would be no flesh saved. But for the sake of God's people, His elect, it would be shortened. We go to history and discover that from 530 A.D. to 1798 A.D. there was such a period of persecution.
(3) Darkening of the sun, in verse 29: "Immediately after the tribulation of those days shall the sun be darkened." Once again we go to history and we discover it is a historical fact, the sun was darkened at midday, May 19, 1780. Look it up. This sign was passed May 19, 1780.
(4) Darkening of the moon. "The moon shall not give her light." When did that happen? It was the night of May 19, 1780. The moon was first dark, and when it did appear it was as red as blood.
"The dark day, May 19, 1780 , so-called on account of a remarkable darkness on that day, extended all over New England...The true cause of this remarkable phenomenon is not known." , From Noah Webster's Dictionary, 1869 edition.
(5) Falling of Stars. "The stars will fall from heaven." Once again we have a historical fact. It was November 13, 1833. That sign was passed.
"The morning of November 13, 1833 was rendered memorable by an exhibition of the phenomenon called shooting stars, which was probably more extensive and magnificent than any similar one hitherto recorded....Probably no celestial phenomenon has ever occurred in this country since its settlement, which was viewed with so much admiration and delight by one class of spectators, and so much astonishment and fear by another class." , From the AMERICAN JOURNAL OF SCIENCE AND ARTS, Volume 25 (1834), pp. 363 and 364.
(6) The second coming, "And then shall appear the sign of the Son of man in heaven." Jesus is even at the door.