The “end of the world” is not the end of the earth but the destruction of the wicked.
3 And as he sat upon the mount of Olives, the disciples came unto him privately, saying, Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world?
The Prophet Joseph Smith said:
“According to [the Savior’s] language, the end of the world is the destruction of the wicked; the harvest and the end of the world have an allusion directly to the human family in the last days, instead of the earth, as many have imagined.”
(Teachings of Presidents of the Church: Joseph Smith , 300.)