'Day of the Lord' in the Bible

Alas, alas for this day. And why? the day of the LORD is at hand, and cometh as a destroyer from the Almighty.

Blow out the trumpet in Zion, and cry upon my holy hill: that all such as dwell in the land, may tremble at it. For the day of the LORD cometh, and is hard at hand:

The LORD shall show his voice before his host, for his host is great, strong and mighty to fulfill his commandment. This is that great and marvelous fearful day of the LORD: And who is able to abide it?

The sun shall be turned into darkness, and the moon into blood, before that great and notable day of the LORD come.

In the valley appointed, there shall be many, many people: for the day of the LORD is nigh in the valley appointed.