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?

​

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

In: 180

Answer 1

When radioactive elements decay, they change into a different element. If the material is already formed, then they just stay there. But if chemical reactions take place, then they’ll react differently, and so move away. If you find a bunch of radium and lead in a sample that, chemically, should just be uranium, then you know that sample crystallized a really long time ago.