Therefore, their ages indicate when they were formed.Because all parts of the solar system are thought to have formed at the same time (based on the solar nebula theory), the Earth must be the same age as the moon and meteorites--that is, about 4.6 billion years old.
Wechat porn girls id - How old is the earth radiometric dating
Once scientists have determined the parent-daughter ratio, they can use this measurement along with half-life of the parent to calculate the age of a rock containing the radioactive isotope.
Radiometric dating has shown that very old rocks--3.5 billion years or older--occur on all the continents.
We know the Earth must be at least as old as any rock on it.
Unfortunately, none of the original rocks still exist, so scientists had to use less direct evidence to determine the age of the Earth.
One line of evidence involves rocks from outside the Earth--meteorites and moon rocks.