Albert Barnes Commentary Acts 2:20

"The sun shall be turned into darkness, And the moon into blood, Before the day of the Lord come, That great and notable [day]." — Acts 2:20 (ASV)

The sun shall be turned into darkness. .

The same images used here with reference to the sun and moon are also used there. They occur frequently (Mark 13:24; 2 Peter 3:7, 10).

The shining of the sun is an emblem of prosperity; the withdrawing, eclipse, or setting of the sun is an emblem of calamity, and is often used in this way in the Scriptures (Isaiah 60:20; Jeremiah 15:9; Ezekiel 32:7; Amos 8:9; Revelation 6:12; Revelation 8:12; Revelation 9:2; Revelation 16:8).

To say that the sun is darkened, or turned into darkness, is an image of calamity, and especially of the calamities of war, when the smoke of burning cities rises to heaven and obscures its light. This is not, therefore, to be taken literally, nor does it provide any indication of what will happen to the sun at the end of the world.

The moon into blood. The word blood here means that obscure, blood-red color which the moon has when the atmosphere is filled with smoke and vapor. It especially refers to the lurid and alarming appearance it assumes when smoke and flames are thrown up by earthquakes and fiery eruptions. Revelation 6:12 states, And I beheld when he had opened the sixth seal, and lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood. .

In this passage, "the moon into blood" denotes great calamities. The figures used are indicative of wars, conflagrations, and extraordinary events such as earthquakes. These things are applied to the destruction of Jerusalem (Matthew 24), and they actually occurred before that event (compare Matthew 24:1 and following for related events).

It may be supposed that Joel's prophecy had an immediate reference to that. Therefore, the meaning of Peter's quotation in this passage is that what occurred on the day of Pentecost was the beginning of the series of wonders that were to take place during the times of the Messiah. It is not implied that those scenes were to end or be exhausted in that age. They may precede that great day of the Lord which is yet to come before the whole earth.

That great and notable day of the Lord. This is called the great day of the Lord because on that day He will be strikingly manifested, more impressively and strikingly than at other times. The word notable (Greek: epiphanē) means signal, illustrious, or distinguished.

In Joel, the word used is terrible or fearful, a word applicable to days of calamity, trial, and judgment. The Greek word rendered notable here is also frequently used in the Septuagint to denote calamity or times of judgment (Deuteronomy 10:21; 2 Samuel 7:23).

This description will apply to any day in which God strikingly manifests Himself, but particularly to a day when He will come forth to punish people, such as at the destruction of Jerusalem or at the Day of Judgment. The meaning is that these wonders should take place before that distinguished day arrives when God will come forth in judgment.