'In that Day' in the Bible

[In that day] the sun will become dark and the moon will [appear] as blood. [This will all happen] before the great and wonderful day when the Lord comes. [Note: Some view these last two verses as a reference to events occurring at the end of time. See Matt. 24:29-30].

They then that received his word were baptized: and there were added unto them in that day about three thousand souls.

And Saul was assenting to his death, and there came in that day a great persecution upon the assembly in Jerusalem, all also were scattered abroad in the regions of Judea and Samaria, except the apostles;