Pandora The New Earth?

Pandora is a moon of the gas giant Polyphemus, (both are figures in Greek mythology) which orbits Alpha Centauri A.

Discovered by the first interstellar expedition twenty-five years ago in 2129, Pandora has been the single most interesting thing to happen to the human race in hundreds of years. The news services love to run clips of the wild scenery on Pandora, and its bizarre flora and fauna.

To the cultures of Earth, which has lost all contact with the natural world, Pandora is mysterious, primal and terrifying. Pandora's atmosphere is a poisonous (to humans) brew of nitrogen, oxygen, carbon dioxide, xenon, ammonia, methane, and hydrogen cyanide. Even from orbit the scope of florae present on the surface indicates a planet brimming with life. One of the creatures on Pandora is the Direhorse, a grey-skinned, hexapodal horse-like animal with bioluminescent qualities that the Na'vi use to hunt with. 

The Na'vi also use the Mountain Banshee to hunt from the air, but a hunter can become prey in the presence of the Great Leonopteryx. In the canopy below, other deadly yet exotic animals roam. Vicious packs of Viperwolves, thick skinned Hammerhead Titanotheres, and the Thanator, the most fearsome of all. Other than the color, the trees resemble those of Earth. They have the familiar trunks and branches and leaves, though, due to the difference in planetary gravity, many of the shapes are strange and the proportions are greater due to the lower gravity. The trees and all plant life of Pandora have formed electrochemical connections between the roots and effectively act as neurons, creating a planet-wide "brain" that has achieved sentience.

Pandora, despite being almost the same size as Earth, is only a moon of the gas giant Polyphemus, which has thirteen other moons. However, due to its smaller size, its gravity is lower than Earth's. Due to Pandora's low gravity, most creatures on Pandora are hexapods, six-legged. Creatures roam the air and forest canopy below, similar to Earth's animals, but on the scale several times larger. Pandora's wildlife also have bioluminescent qualities. Depending on the position of the various moons, Pandora can have two or even three moons in its sky at once. Pandora and the other moons cast large black shadows on Polyphemus.