"The sun will be turned into darkness, and the moon into blood, before the great and terrible day of Yahweh comes." (Joel 2:31)

This data may — and probably does — point to the "Day of Yahweh" in the Scripture (otherwise also known as the "Day of the Lord") in which God dispenses his wrath upon those who have rejected Jesus Christ as their personal Lord and Savior. This is a mostly scientific document (easy-to-read, however, so do not be shy).

Lunar eclipse of May 15, 2003 taken by Loyd Overcash of Houston, Texas (source).