Earth History

planetary accretion

4600 BCE

1 year = 1 million years.
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, in an accretion disk. Most astronomical objects, such as galaxies, stars, and planets, are formed by accretion processes.

Earth core formation

4540 BCE

1 year = 1 million years.
The first rocky bits of Earth coalesced around 4.54 billion years ago, less than 100 million years after the solar system formed. For much of those early years, Earth was a blob of molten rock, but over time, the surface cooled and formed a crust that floated on the Earth's liquid core.

planetary cooling

4500 BCE

1 year = 1 million years. 4500 million years = 4.5 billion years.
A planetary body, whether the body is a planet or a moon, has to cool off. The warmth contained inside a body controls what sort of surface activity, atmospheric activity, and interior activity which the body has. As planetary bodies cool slowly, heat diminishes, and the activities diminish to nothing.

formation of the moon

4500 BCE

1 year = 1 million years.

End of Heavy Bombardment

4000 BCE

1 year = 1 billion years.
About 4 to 3.8 billion years ago a period of intense comet and asteroid bombardment is thought to have peppered all the planets including the Earth. Many of the numerous craters found on the Moon and other bodies in the Solar System record this event.