TNRTB Archive – Retained for reference information
Detection of a short-lived radioactive isotope provides new evidence for an old Earth. One of the most compelling evidences for an ancient Earth is the absence today of short-lived radioactive isotopes in the earth’s crust and in primitive meteorites left over from the time of the solar system’s formation. From a young-earth perspective, if Earth is only 6,000 -10,000 years old, then these short-lived radioactive isotopes should still be present on Earth and in meteorites, but because of their short half-lives (of perhaps hundreds or thousands of years) they have completely decayed. This new report provides evidence that short-lived radioactive isotopes were indeed present in primitive meteorites. Researchers detected the sulfur-36 isotope produced by chlorine-36 decay in the Ningqiang carbonaceous chondrite meteorite that dates to 4.560 billion years in age, close to the time that the solar system formed. Chlorine-36 (which has a half-life of 0.3 million years) would have become extinct within 6 million years after the solar system’s formation. Thus, Earth must be at least 6 million years old. This direct evidence for a short-lived radioactive isotope, and its absence in primitive meteorites today, compels the conclusion that the solar system, and hence the earth, is indeed old.
- Yangting Lin et al., “Short-Lived Chlorine-36 in a Ca- and Al-Rich Inclusion from the Ningqiang Carbonaceous Chondrite”, Proceedings of the National Academy of Sciences, USA 102 (2005): 1306-11
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