The sun will turn to darkness and the moon to blood before the day of the Lord comes, that great and shining day.
In context
18Yes, even on my servants, men and women alike, I will pour out my Spirit in those days, and they will prophesy. 19I will set wonders in the sky above and signs on the earth below: blood and fire and a haze of smoke. 20The sun will turn to darkness and the moon to blood before the day of the Lord comes, that great and shining day. 21And everyone who calls on the name of the Lord will be saved.’ 22Men of Israel, hear these words. Jesus the Nazarene was a man marked out for you by God through the mighty deeds, wonders and signs that God did among you through him, as you yourselves know.