Christ hung upon the cross for a period of about six hours, from approximately 9:00 A.M. until 3:00 p.m. It was during the last three hours that darkness covered the land, as apparently the agonies of Gethsemane returned (see Jesus the Christ, p. 661; Mortal Messiah 4:224-26).
Of this period Elder Bruce R. McConkie writes:
“He will continue to suffer the curses of crucifixion for another three hours, until around 3:00 P.M. when he voluntarily gives up the ghost. Of these coming hours, Matthew and Mark say only that it was a period when there was darkness over all the land; Luke extends this turning of day into night over a greater area.
’There was a darkness over all the earth, ’ he says, ’and the sun was darkened.’ The fact of the darkness, for which there is no known scientific explanation, is known to us, but its purpose and what happened during those three seemingly endless hours remain outside the bounds of our understanding. Could it be that this was the period of his greatest trial, or that during it the agonies of Gethsemane recurred and even intensified?”