KJV: "Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken"
RSV: "Immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light, and the stars will fall from heaven, and the powers of the heavens will be shaken".
Point 1: There's no indication that the darkening of the Sun is the
cause of the darkening of the moon.
Point 2: In both translations, the light is specifically attributed to the moon itself ("her light", "its light").
Point 3: In the very next phrase of the verse, a scientific impossibility is asserted - that the stars will "fall from heaven".