Blue is the fourth of ten planets, orbiting an orange dwarf star at a distance of about 120 million kilometers. It is an earthlike planet, with twin moons and a vast ocean of deep indigo seawater. There are polar icecaps, and a plethora of islands with purple vegetation dot the seascape. Living on the planet are Bluwans, subaquatic humanoids with light blue skin. Their physiology and gender dimorphism is mostly identical to that of humans. The six-chambered heart, on the right side of the chest, pumps copper-based, teal blue blood throughout the body. The hands and feet are webbed.