Hadean and Earth's formation

When did Earth first form

~4.56 billion years ago

How was the Earth formed

Formed from a cloud of gas and dust. Accretion of particles within the solar system crashed into each other and stuck together forming larger and larger bodies. Gravitational collapse caused matter to clump together, forming a proto-Earth. Early Earth was hot, with frequent collisions, volcanic activity, and molten surface.

How was the moon formed

Likely formed with debris from a collision of Earth with a Mars-sized body (protoplanet)

How were oceans formed

Earth's early atmosphere was composed of hydrogen and helium. As the the crust began to form, volcanic eruptions occurred frequently, pumping water vapor, ammonia, and carbon dioxide into the atmosphere around Earth. Slowly, the oceans began to take shape, and eventually, early life evolved in those oceans

What was the sun like ~4bn years ago

Sun was ~30% dimmer