“But in those days,
After that suffering,
Will be darkened.
Will not give its light.”
Ἀλλὰ ἐν ἐκείναις ταῖς ἡμέραις μετὰ τὴν θλῖψιν ἐκείνην ὁ ἥλιος σκοτισθήσεται, καὶ ἡ σελήνη οὐ δώσει τὸ φέγγος αὐτῆς,
This is almost word for word in Matthew, chapter 24:29, with a vague reference to this in Luke, chapter 21:25. Mark indicated that in those days (Ἀλλὰ ἐν ἐκείναις ταῖς ἡμέραις), after the sufferings (μετὰ τὴν θλῖψιν), there would be a cosmic upheaval. The sun would be darkened (ὁ ἥλιος σκοτισθήσεται). The moon would not give its light (καὶ ἡ σελήνη οὐ δώσει τὸ φέγγος αὐτῆς). The assumption was that the moon had its own source of light, not merely a reflection of the sun. This was fully in line with the great Israelite prophetic tradition of the Day of Yahweh, as in Ezekiel, chapter 32:7, Joel, chapter 2:10, Amos, chapter 8:9, and Zephaniah, chapter 1:15.