What type of 'clock' dictates the aging process for a planet like Earth, contrasting with stellar dating?

Answer

The predictable decay of radioactive isotopes (a chemical clock)

Planets like Earth can be dated using the precise, known half-lives of radioactive elements, which acts as a chemical clock, whereas stellar dating relies on physics related to mass conversion to energy.

What type of 'clock' dictates the aging process for a planet like Earth, contrasting with stellar dating?
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