'Darkness' in the Bible

A day of darkness and gloom,A day of clouds and of thick [dark] mist,Like the dawn spread over the mountains;There is a [pagan, hostile] people numerous and mighty,The like of which has never been beforeNor will be again afterwardEven for years of many generations.

“The sun will be turned into darknessAnd the moon into bloodBefore the great and terrible day of the Lord comes.