抄録
The Earth is a planet of the Solar system. The Solar system is located in an arm of the spiral galaxy. The galaxy is a small member of the universe. Therefore, the formative field of the Earth should be discussed from a viewpoint of a part of the universal open system. The universe is composed of many levels of the hierarchy. They are atoms, minerals, rocks, planets, stars, galaxies and their groups from small to large. We examine whether the Sun and the Earth are unique existences or general ones in each level of the universal hierarchy. This examination should be the constraint of the prehistory of the Earth.
