The Sun Turned into Darkness and the Moon into Blood
Old Testament: Joel 2:31
The sun shall be turned into darkness, and the moon into blood: before the great and dreadful day of the Lord doth come.
Old Testament, also: Joel 2:32
And it shall come to pass, that every one that shall call upon the name of the Lord shall be saved: for in mount Sion, and in Jerusalem shall be salvation, as the Lord hath said, and in the residue whom the Lord shall call.
New Testament: Acts 2:16, 20; Apocalypse 6:12
But this is that which was spoken of by the prophet Joel... The sun shall be turned into darkness, and the moon into blood, before the great and manifest day of the Lord come... And I saw, when he had opened the sixth seal, and behold there was a great earthquake, and the sun became black as sackcloth of hair: and the whole moon became as blood:
The connection
This is one of the few places where Scripture shows its own method plainly. Peter, standing up at Pentecost with the noise of the wind still in the room, does not say that Joel is about to be fulfilled. Peter says this is that which was spoken of by the prophet Joel, and then quotes the oracle at length, sun and moon and the great day included, though no one in Jerusalem that morning saw the moon turn to blood. Peter is claiming the prophecy for an event that does not look like its own literal terms, and he is right to, because the thing Joel promised had happened: the Spirit was poured out, and the very next line of the oracle, which Peter goes on to quote, is that everyone who calls on the name of the Lord shall be saved. Yet John, writing decades after Pentecost, takes the same images and puts them at the opening of the sixth seal, still ahead. Neither is a misuse. The oracle is not a dated forecast that gets spent once; it is a description of what it is like when God draws near to judge and to save, and that nearness has more than one moment. It reached one at Calvary when darkness covered the whole earth, another at Pentecost, and it reaches its last at the end. Joel himself joins the two halves in a single breath, terror in verse thirty one and salvation in verse thirty two, so that the darkening sky and the open door are never two separate announcements.
Moral sense
The same day is dreadful and saving depending on nothing but whether a man calls on the name of the Lord, and Joel puts the invitation in the sentence immediately after the terror rather than as a separate offer.
Anagogical sense
The language stretches from Calvary to Pentecost to the sixth seal because one and the same coming is being described at three depths, and only the last of them exhausts it.
The Fathers
Victorinus of Pettau, Commentary on the Apocalypse, on ch. 6, reads the sixth seal ecclesially rather than astronomically: "The sun becomes as sackcloth; that is, the brightness of doctrine will be obscured by unbelievers," and "By the moon of blood is set forth the Church of the saints as pouring out her blood for Christ." St Bede, Explanation of the Apocalypse, Book I, on 6:12, reads the moon of blood as Victorinus does: "The Church, more than is wont, will shed her blood for Christ." He also likens the darkened sky to Calvary: "By the opening of the sixth seal the last persecution is announced, and that the world is shaken with darkness and fear, as when the Lord was crucified on the sixth day of the week."
Warrant
The identification is the New Testament's own: Acts 2:16 names the prophet Joel outright and then quotes the oracle at length, sun and moon and the great day included. Apocalypse 6:12 reaches for the same paired images of a darkened sun and a blood-red moon at the opening of the sixth seal, drawing on the same oracle at a later point in the book and without attribution there. That one prophecy is claimed as already fulfilled at Pentecost and still awaited at the sixth seal is the point of this entry rather than a difficulty in it. Checked in the Greek, and Acts is quoting the Septuagint closely: helios, selene, haima, skotos, prin, megas and epiphanes all stand at Joel 2:31 in the Septuagint and again at Acts 2:20, with helios, selene and haima carried on into Apocalypse 6:12. Douay follows the Vulgate's three chapter Joel where the Greek divides it into four, so this verse is Joel 3:4 in the Septuagint.
Catechism of the Catholic Church, paragraph 1040.
The verses
Joel 2:31 · Joel 2:32 · Acts 2:16 · Acts 2:20 · Apocalypse 6:12
