If uranium-238 is formed in a star (supernova), how can it be used to date the age of the earth? Aren’t you dating the age of the supernova? What about earth’s formation creates a marker that can be dated with isotopes?

Question

So how do you get 4.5 billion years by dating isotopes that existed long before the formation of the earth?

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Edit: I’m not creationist trolling. I believe the #, just trying to learn about the sicence.

In: 180

Answer 1

Dating involves measuring parent and daughter isotopes in most situations (14C is the unusual exception). If you want to date using a decay series, there are two main methods: find a mineral that does not include any daughter isotope at time of formation (so any and all daughter isotope in that sample must have formed by decay of the parent), or measure many minerals and correlate the contents of parent and daughter (making a linear relationship) to establish the parent content via y intercept (the parent content for all minerals formed at that time if they had formed without the daughter).

There are loads of other ways to play with the data to define ages, too.