Hadean Eon – The Newborn Earth

Key Events

  • The Earth forms through accretion (rubble from the Solar System clumping together).
  • Initially, its surface is molten.
  • As Earth cools, minerals separate based on density to create the crust, mantle and core.
  • The Moon forms, most likely through a collision betweenEarth and a body the size of Mars, 4,500 million years ago.
  • Earth becomes covered in water.
Illustration of the Hadean Eon. Copyright: Vix Southgate

Facts, Debates & Trivia

  • The eon is named after Hades, god of the Underworld, because of the hellish conditions.
  • We don’t know how or when Earth acquires its water. It might come from impacts by icy comets or be ‘outgassed’ from water held internally.
  • Just like Earth, Mars also acquires water during this time.


  • The newborn Earth is a hostile environment!
  • Temperatures are scorching hot from the accretion process and heating from radioactive elements.
  • There are high radiation levels.
  • Earth has  frequent collisions with other bodies in the Solar System.
Artist’s impression of the Hadean Earth. Credit: S Marchi.


4,600-4,000 million years ago (600 million years)

1 metre = 
20 million years

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