Mark 15:33

And when the sixth hour was come, there was darkness over the whole land until the ninth hour.

The supernatural darkness that enveloped the whole earth at that time was foretold by the prophet Amos (Amos 8:9); since it was the full moon, no eclipse of the sun was possible, the darkness here having been caused by "the sun's light failing" (Luke 23:45). It signified, among many things, the summary end of the sabbath day, the presence of God himself in the events of that day, and the mantle of loving privacy that God cast over the shameful business of that awful day. For more extensive comments on the nature and meaning of this darkness, see my Commentary on Matthew, Matthew 27:1.