The Hadean is the first eon of Earth's history. It begins with the formation of the planet about 4.54 billion years ago, when the young Earth was bombarded by leftover rock and metal and was largely molten.
A collision with a Mars-sized body early in the eon is thought to have thrown out the material that became the Moon, and the oldest known Earth minerals, zircon crystals from Western Australia, are about 4.4 billion years old.
Explore this era on the timeline
Key events of the Hadean
4 events are on the timeline for this era; these are among the most notable, in date order.
- about 4.54 billion years agoFormation of the Earth
- about 4.51 billion years agoFormation of the Moon
- about 4.4 billion years agoOldest known Earth minerals
- from about 4.1 billion years ago to 3.8 billion years agoLate Heavy Bombardment