How do you calibrate a tool to measures a 4.6 BILLION-year-old rock?
Just because you and your buddies down at the feedstore, swigging 'shine, "can't imagine" something...
Seriously: Literally thousands of man-years have been expended in researching this.
Regards,
A lot of assumptions. The radioactive isotope uranium-238 has a half-life of 4.47 billion years. That is one of the tools. Lets say they find a piece uranium-238 is near its first half life. The assumptions are it didn't arrive as a comet. Or a sun flare and deposit it. There are methods that we use to speed up the decay which means in nature this could take place.
Analysis of radioactive isotope ratios. Since radioactive elements decay at known rates, determining the ratios is like gauging the age of a campfire by evaluating the heat and ratio of ash to wood.
If you had watched the movie My Cousin Vinny, you would have an idea as to how..