冥めい王おう代だい

noun

Hadean; Hadean eon

Geological term for the earliest eon of Earth's history, before the Archean. Used in academic and scientific contexts.

• 冥めい王おう代だいは地ち球きゅうが形けい成せいされた約やく46よんじゅうろく億おく年ねん前まえから40よんじゅう億おく年ねん前まえまでの期き間かんを指さす。

  The Hadean eon refers to the period from about 4.6 billion to 4 billion years ago when the Earth was formed.