"May 19, 1780, stands in history as “The Dark Day.” Since the time of Moses no period of darkness of equal density, extent, and duration, has ever been recorded. The description of this event, as given by eyewitnesses, is but an echo of the words of the Lord, recorded by the prophet Joel, twenty-five hundred years previous to their fulfillment: “The sun shall be turned into darkness, and the moon into blood, before the great and terrible day of the Lord come.” Joel 2:31 . GC 308.1"
"The sun shall be turned into darkness, and the moon into blood, before the great and the terrible day of the Lord come."
Ellen White directly references Joel 2:31 in this passage.