Gumi

Gumi (구미) is a natural satellite orbiting Maijo (마이조). It is the largest, and densest satellite in the Maijo system, as well as one of the two bodies capable of supporting life.

According to radiometric dating, Gumi formed some 3.3 billion years ago, and within its first billion years, simple life appeared in its oceans (in the form of colonial algae and unicellular bacteria) and began to affect its atmosphere, causing the formation of an ozone layer and the rise of its atmospheric oxygen content. Since then, the combination of certain properties has allowed complex life to thrive and evolve.

Gumi's lithosphere is divided into several rigid plates that move across its surface over a period of millions of years. Due to tidal heating, Gumi has a relatively high geologic activity, and its tectonic plates are broken up into more pieces compared to Earth. Gumi's atmosphere is relatively thick compared to bodies of the same size. This is due to the high percentage of heavy gasses (such as xenon and krypton), and tidal heating. Gumi's interior remains active with a solid iron inner core, a liquid outer core that generates the magnetic field, and a convecting mantle that drives plate tectonics.