Aryabhata's day of Brahman — one kalpa — works out to about 4.35 billion years. Modern radiometric dating puts Earth at 4.54 billion years old. A 6th-century Sanskrit astronomy text and a 20th-century radioactive-decay measurement agree to within 5%. Coincidence — Aryabhata was doing planetary period calculation, not geology. But the order-of-magnitude match is real.