And I saw a new Heaven and a new Earth: for the first Heaven and the first Earth were passed away; and there was no more sea. And I John saw the holy city, new Jerusalem, coming down from God out of Heaven, prepared as a bride adorned for her husband. (Revelation 21:1-2 AKJV)
The First Heaven is widely accepted as the spirit realm that surrounds the Earth. This is stating that the Earth and the atmosphere and even where it contacts the spirit realm will be gone. When we “pass away” if we are Christians, we enter the Third Heaven where God lives.
The word “coming down” is translated from the Greek word katabainō which can mean “of celestial beings coming down to Earth.” Even though the language says “coming down” could it be possible that Heaven’s atmosphere is enveloping Earth? From Earth’s perspective, it would seem like it was descending, but it may actually be our planet moving into the realm of the Third Heaven where God dwells.