Jun II, the terrestrial world, is composed of 40.0% iron, 29.5% oxygen, 17.2% silicon, 6.2% titanium, 5.5% calcium, 1.3% other metals, and 0.3% other elements. Its atmosphere is 82.4% nitrogen, 17.6% oxygen, with other trace gases, and is 18% the pressure of Earth's. Temperatures on the surface run from -86 °C to 40 °C. The average is 21 °C.
The Yamatai Star Empire placed a global communications networks of Emrys Satellites into orbit in YE 36. Since YE 38, Trinary Star Shipping has maintained parcel shipping centers in all of Jun's major cities.
The Jun system is named after Doshii Jun.