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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?

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    $\begingroup$ Welcome. Your questions can be answered (the last one has some uncertainty). Would you choose one ? And I kindly ask to perform a lil' search because much if not all has already been written. Concentrate on most recent information (2016 and later). $\endgroup$ – user20217 Jun 7 at 20:48
  • $\begingroup$ Thank you for your help. I'll do some searching. $\endgroup$ – RandallSmith Jun 8 at 4:03
  • $\begingroup$ 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. The time taken for the terrestrial (rocky) planets to form was less than 100 million years. $\endgroup$ – Fred Jun 8 at 18:46