Origin of Earth

Origin of life is linked to origin of earth. Cosmos, the Universe originated 10–20 billion years ago by Big Bang (thermonuclear explosion). Its part, a galaxy, (e.g., our Milky Way) comprises millions of stars, (our Sun is one of those).

Sun, its planets and satellite constitute the solar system. Our earth is the 3rd planet with rocks, water & atmosphere. It began as gaseous clouds of metals and non-metal atoms, later condensed to form surface rocks and boiling fluid core with gaseous atmosphere. Oldest surviving rock is 4.3 billion year old (without trace of life). 3.9 billion year old Rocks had carbonates denoting life processes. The oldest microfossils (of Cyanobacteria) are 3.3–3.5 billion years old.