Antartic radioactive dating of meteorites dcdatingresourceguide com
Meteorites are among the oldest objects we know about - formed about 4.5 billion years ago. This article describes the principles and methods used to make that determination.
There are well-known methods of finding the ages of some natural objects.
The terrestrial ages of Antarctic meteorites were estimated from the thermoluminescence (TL) intensity of the fusion crest.
It was found that there is a good correlation between the TL intensities and terrestrial ages which were previously measured by cosmogenic-radionuclide abundance.
Obviously there are complexities, but there are not critical for this answer.
Short answer: because the meteorites formed together with the Earth and the rest of the Solar System.
It was also noticed that the LT/HT value gives false terrestrial ages.
"The idea that Rb-Sr is the most used chronometer for meteorites is largely based on work done 10-30 years ago.Trees undergo spurts in growth in the spring and summer months while becoming somewhat dormant in the fall and winter months.When a tree is cut down, these periods are exhibited in a cross section of the trunk in the form of rings.Simply counting the number of rings will give one a fairly good idea of the age of the tree.Periods of heavy rain and lots of sunshine will make larger gaps of growth in the rings, while periods of drought might make it difficult to count individual rings. When a given quantity of an isotope is created (in a supernovae, for example), after the half-life has expired, 50% of the parent isotope will have decomposed into daughter isotopes.