General:

* Ancient (referring to its age)

* Active (referring to its geological processes)

* Aqueous (referring to its abundance of water)

* Amazing (referring to its beauty and complexity)

* Astonishing (referring to its wonders and mysteries)

Specific:

* Arid (referring to dry, desert-like regions)

* Aquatic (referring to its oceans and water bodies)

* Atmospheric (referring to its air and weather)

* Abundant (referring to its rich biodiversity)

* Alluring (referring to its captivating beauty)

Figurative:

* Azure (referring to the color of the sky)

* Alive (referring to its teeming life and ecosystems)

* Aetherial (referring to its vastness and mysteriousness)

* Avian (referring to its diverse bird life)

* Arboreal (referring to its forests and trees)

You can also use adjectives that describe specific features of Earth, such as:

* Arid (desert)

* Alpine (mountains)

* Arctic (polar regions)

* Aquatic (oceans)

* Agricultural (farmlands)

The best adjective will depend on the specific context and what aspect of Earth you want to emphasize.