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Comment by beckman466 | Hacker News Reader

> The Peekskill meteorite is estimated to be 4.4 billion years old.

If everything in the universe is the same age (emerging from the big bang), is 4.4 billion years the last time the meteorite had a serious physical transformation (to it’s current form)? If not, what is meant with 4.4 billion years old?

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A meteorite is "formed" when disparate elements in gaseous form coalesce into solid masses, which then accrue into a larger solid mass. Larger objects will undergo further processes, such as gravitational differentiation (forming layers of denser materials nearer the core) and become more spherical (again, due to gravity).

The actual process from gas to final rock takes a much shorter time of span than has passed since it occurred. Thus, we can say that the whole process happened 4.4 billion years ago without there being much importance to e.g. the gas coalescing into microscopic grains 4.4832 billion years ago and the near-final shape of the object being established 4.3681 billion years ago.

Its was flung out of a exploding sun.. so the radioactive decay of the supernova material started 4.4 billion years ago?

Thats 19,130434783 galactic years.. so in theory that sort of debris once caught could come from anywhere in the galaxy we tumbled through

The meteor was not flung out of an exploding sun. The elements that would later form the metor - iron for instance - were flung out of an exploding sun. This likely happened far earlier than the 4.4 billion year age of the rock. Considering _that sun_ was itself a second population sun, that event probably happened closer to 6 to 8 billion years ago (personal estimate based on the lifetime of third- and second- population stars and the estimated age of the universe).

And it wasn't solid iron at that point, rather disperse iron atoms.

The same way it makes more sense to celebrate when a person was born[1] than to celebrate when the atoms of their body was formed.

[1] Regardless of https://youtu.be/T5f8WoV0zbQ

I wonder if there is any culture out there that celebrates "conception day" as opposed to birthday.

Interesting thought.

I'm not at all into the proper side of science, but one thing that strikes me is that since conception doesn't have to lead to a child being born [1], celebrating the final more obvious "success case" makes more sense to me.

[1] https://en.wikipedia.org/wiki/Miscarriage

I previously thought Korea worked this way bit it seems it's a lot more puzzling than I thought.

https://overseas.mofa.go.kr/no-en/brd/m_21237/view.do?seq=33....

It sure would make some things more convenient.

My daughter arrived 10 weeks premature and with her being only 16 months old now since birth, whenever we’re asked her age it’s normally for people to compare her progress developmentally and we have to do a quick calculation in our heads.

It made me realise that date of birth is not especially significant compared to date of conception.

Fortune as time goes on it will matter less.

Those 10 weeks don’t mean much later in life though. One is really only occupied by ones child’s development on a weekly basis for a year or so. Enjoy it, even if you have to do more math than usual.

Who wants to think about their conception?

*shudders*

See if I invite you to my 4.4 billionth birthday party

It means it was formed right along with the rest of the planets. The sun is not a first generation star, that's why we have all those heavy elements here out of which more complex constructs are made. So not everything is 'the same age'.

To make this more precise, it refers to the nuclear transformation of elements.

Yes, in the same way your car might be 5 years old the age refers to the time the object was formed not the age of the matter/energy in it.

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