How do we know the age of a
- how do we know the numerical age of a cratered surface
- how do we know the age of a planet
- how do we know the age of a cat
- how do we know the age of a greenland shark
- how do we know the age of a galaxy
- how do we know the age of a rock
- how do we know the age of a star
- how do we know the age of a fossil
- how do we know the age of a tree
