Mormon makes the statement that by the power of the word of the Lord, "the earth goeth back, and it appeareth unto man that the sun standeth still . . . " (Helaman 12:15). According to Cleon Skousen, if the Lord commands the earth to turn back on its axis so that it lengthens the day many hours, it is done. This is precisely what the Bible says occurred in the days of Joshua:
Then spake Joshua to the Lord in the day when the Lord delivered the Amorites before the children of Israel, and he said in the sight of Israel [and apparently by instruction from the Lord], Sun, stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon. And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies. Is not this written in the book of Jasher? So the sun stood still in the midst of heaven, and hastened not to go down about a whole day (twelve hours)." (Joshua 10:12-13).
The same thing appears to have happened in the days of Isaiah. The good king Hezekiah was about to die around 711 B.C. when Israel was threatened with attack by the Assyrians and the king felt he should be allowed to live. Isaiah was told to tell him that his life would be extended another fifteen years and that his enemies would be overcome. Then the scripture says: "And this shall be a sign unto thee from the Lord, that the Lord will do this thing that he hath spoken: Behold, I will bring again the shadow of the degrees, which is gone down in the sun dial of Ahaz, ten degrees backward. So the sun returned ten degrees, by which degrees it was gone down." (Isaiah 38:7-8; see also 2 Kings 20:8-11) [W. Cleon Skousen, Treasures from the Book of Mormon, Vol. 3, pp. 3305-3306]