Most scientists and many Christians believe that the radiometric dating methods prove that the earth is 4.5 billion years old.
The textbooks speak of the radiometric dating techniques, and the dates themselves, as factual information.
There are at least 67 different uniformitarian (the present is the key to the past) methods of dating the earth other than long-age radiometric dating: each of which yield ages of less than 500 million years.
The commonly accepted 4.5 billion year age of the earth is derived from radiometric dating of lunar rocks and meteorites in addition to dating methods based on the Gerling-Holmes-Houtermans model. Those who developed the method utilized Pb, lead isotopes that are the product of radioactive decay, normalized to 204Pb.
Dalrymple (2004) cites examples of lead isotope dating that give an age for the earth of about 4.5 billion years.
Lead isotopes are important because two different lead isotopes (U).
What is less commonly known are any of the details of how the issue was settled: such as that the 4.5 billion year 'date' came from a single meteorite that was assumed to be the same age as the earth's core.
And since this favored 'date' is the only one that's trumpeted by the media it is the only date that many assume to be correct.