I was reading a commentary of St. John Chrysostom on this verse : "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 : And then shall appear the sign of the Son of man in heaven : and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory."
He said : "The very creation being then transfigured, for « the sun shall be darkened », not destroyed, but overcome by the light of His presence ; and the stars shall fall, for what shall be the need of them thenceforth, there being no night ? And « the powers of Heaven shall be shaken », and in all likelihood, seeing so great a change come to pass. For if when the stars were made, they trembled and marvelled ( « for when the stars were made, all angels », it is said, « praised Me with a loud voice » ) ; much more seeing all things in course of change, and their fellow servants giving account, and the whole world standing by that awful judgment-seat, and those who have lived from Adam unto His coming, having an account demanded of them of all that they did, how shall they but tremble, and be shaken ?"
I don't know why, but he did not mention the moon which stops to give its light, but he commented only on the sun and the other things. Maybe he forgot. Anyway he says : "and the stars shall fall, for what shall be the need of them thenceforth, there being no night ?" ; but following this reasoning the moon should also disappear since there will be not anymore night, How could we see it ? What would be its purpose ? Same for the sun, if Christ is our light and we enter in an everlasting day, What is the purpose of the sun ? But St. John Chrysostom says : "for « the sun shall be darkened », not destroyed, but overcome by the light of His presence." Maybe in a first time the sun shall be darkened, but after that, the sun as well as the moon shall fall too, as the other stars.. I don't know, just supposing.. This leads me to ask : Are the sun and the moon everlasting ? Indeed, in the Psalm 89 ( Septuagint ), it says : "Once for all I swore in my Holy Place, that I would not lie to David, his seed shall remain forever, and his throne as the sun before Me, and as the moon that is established forever and is a faithful witness in heaven." Can this verse be interpreted as meaning that the sun and the moon are everlasting ?