Raijin

Raijin is a planet orbiting the star Gliese 570 A.

Characteristics
Raijin is often considered to be an "Ammonia Earth" due to its vast oceans made of a varying mixture of ammonia and water. It is a massive planet, being over 5 times more massive than Earth, and orbits 2.25 times more distant from Gliese 570 A than Earth does from its Sun. It is the largest and most distant of Gliese 570 A's three planets.

Raijin's thick atmosphere is tinted by various biological and non-biological processes, rendering it in a moderate shade of green, and its density mostly obscures the barren continents and ammonia oceans below. The planet enjoys mostly uniform energy distribution thanks to a low degree of axial tilt and volcanic activity fueled by its high mass. Raijin's surface is 78% liquid ammonia, with the other portion belonging the two barren, brown continents of Jurōiin and Ebisu.

Life on Raijin exists mostly in the oceans, and has achieved complex multicellular forms in its warmer depths. The ecosystem is quite different from Earth's, as ammonia serves as a solvent instead of water in Raijin's alien biochemistry.

Raijin has three major moons: Kaminari, Raiden, and Narukami. All named after alternate names of Raijin itself.

Etymology
Raijin is named for the Japanese god of thunder, as it was initially believed to be a gas dwarf before it was further observed.

Discovery
Raijin was discovered in 2040 by the JEEPS (Japanese Extrasolar Earthlike Planet Survey) satellite, when the craft directly observed the planet, along with the other two worlds in the system. The planet's mostly ammonia-based makeup and location in the outer system led scientists to first believe it was a tiny gas giant (a "gas dwarf" with no solid surface), but when its mass and radius were verified it was strikingly found to be a terrestrial world with an atmosphere and surface laced with liquid ammonia and ammonia vapors. Raijin was the first "Amunian" (that is, an Earth-twin with ammonia instead of water as its primary solvent) world with such qualities to be confirmed.

Exploration & Colonization
Raijin was never cited as a worthy location for colonizing at its discovery (due to extremely cold temperatures, high gravity and high atmospheric pressure), but still held great scientific significance.