Acts 2:20 (NIV)
The sun will be turned to darkness and the moon to blood before the coming of the great and glorious day of the Lord.
Revelation 6:12-13 (NIV)
12I watched as he opened the sixth seal. There was a great earthquake. The sun turned black like sackcloth made of goat hair, the whole moon turned blood red,
13and the stars in the sky fell to earth, as late figs drop from a fig tree when shaken by a strong wind.