<p>Does that mean that the Earth gained the classification of a planet that long ago rather than some other celestial body? How did they determine that this happened that long ago? How discrete is the period of non planet to planet?</p>

CC BY-SA 4.0
2020-06-08T04:03:24.020Z
Thank you for your help. I'll do some searching.
RandallSmith
CC BY-SA 4.0
2020-06-08T18:46:39.057Z
The proposed duplicate question, only answers the second question. The answer to the last part can be found in [*Formation and evolution of the Solar System*](https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System). The time taken for the terrestrial (rocky) planets to form was less than 100 million years.
Fred
<geology><earth-history>
What do scientists mean when they say the Earth formed 4.56 billion years ago?
RandallSmith
# What do scientists mean when they say the Earth formed 4.56 billion years ago?

(Asked by: username_0 on 2020-06-07)

Does that mean that the Earth gained the classification of a planet that long ago rather than some other celestial body? How did they determine that this happened that long ago? How discrete is the period of non planet to planet?

**Tags:** geology, earth-history

> **Comments:**
> **username_0**: Thank you for your help. I'll do some searching.  
> **username_1**: The proposed duplicate question, only answers the second question. The answer to the last part can be found in [*Formation and evolution of the Solar System*](https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System). The time taken for the terrestrial (rocky) planets to form was less than 100 million years.  

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