After the Last Day, there are no more days, we are into the eternal state. The sun and moon no longer mark the progression of time.
God gave us them to mark the times and seasons at the creation of this world.
The sun, moon, stars are all passing away at the return of Christ
You see then there can be no earthly millennial reign of a 1000 years, with the sun and moon and stars marking out the days, months, seasons after Christ's return.
As the former things have passed away.
Christ's own word show that the sun and moon turn dark, the stars are gone from the sky, they are no more, their usefulness is at an end.
The see Him at His returning because He returns in flaming fire, Christ is the Light.
Mark 13
21 “Then if anyone says to you, ‘Look, here
is the Christ!’ or, ‘Look,
He is there!’ do not believe it. 22 For false christs and false prophets will rise and show signs and wonders to deceive, if possible, even the [
g]elect. 23 But take heed; see, I have told you all things beforehand.
The Coming of the Son of Man
24 “But in those days, after that tribulation, the sun will be darkened, and the moon will not give its light;
25 the stars of heaven will fall, and the powers in the heavens will be shaken.
26 Then they will see the Son of Man coming in the clouds with great power and glory. 27 And then He will send His angels, and gather together His [
h]elect from the four winds, from the farthest part of earth to the farthest part of heaven.
Rev 21
The Glory of the New Jerusalem
22 But I saw no temple in it, for the Lord God Almighty and the Lamb are its temple. 23 The city had no need of the sun or of the moon to shine [
a]in it, for the [
b]glory of God illuminated it.
The Lamb is its light. 24 And the nations [
c]of those who are saved shall walk in its light, and the kings of the earth bring their glory and honor [
d]into it.
Revelation 22:5
There shall be no night there: They need no lamp nor light of the
sun, for the Lord God gives them light. And they shall reign forever and ever.