In Ps. 102:25–26 it is stated: “Of old Thou didst lay the foundation of the earth, and the heavens are the work of Thy hands. They will perish, but Thou dost endure; they will all wear out like a garment.” Heaven and earth are gradually changing, growing old, and directing their course toward corruption. But later they will put on a new garment. For God will make not only the earth but also heaven itself far more beautiful when it has been stripped of its old garment. These are only workday clothes; afterwards they will put on an Easter coat and a Pentecost garment. Today the brightness and splendor of the light of the sun is not as great as it will be after this life; nor is the strength of the rest of the creatures as great as it was at the beginning of creation. Thus farmers testify that nature is gradually growing old, that 30 or 40 years ago trees, whether they were in forests or in gardens, grew up more quickly than they do now, and that the growth of six or seven years on the trees of these times barely equals a years increase of the earlier age.
Therefore the earth will be adorned with another garment, and heaven and the heavenly bodies will be much more splendid, as is stated in Is. 30:26: “The light of the moon will be as the light of the sun, and the light of the sun will be sevenfold.” An old coat that is torn must be replaced with a new one.
In the same manner God also cleanses us from sins and frees us from death. This is the work of the six days of this world. But when these are past, when we have entered into His rest, then our torn and filthy garment will be changed into the garment of the eternal Sabbath (cf. Heb. 4:3–9).
Luther’s works, vol. 8: Lectures on Genesis: Chapters 45-50