Seven-Billion-Year-Old Stardust Grain Sheds Light on Galactic History
A silicon carbide grain embedded in the 1969 Murchison meteorite fell in Victoria and has been dated to about seven billion years old, indicating it condensed in the outflow of a dying star before the Sun formed. The age is an exposure-based neon-21 clock, not the meteorite’s age, and represents one of the oldest solid materials on Earth, pointing to a burst of star formation in the Milky Way around seven billion years ago. Recent Bennu samples also contain presolar grains, confirming interstellar stardust survives to become part of solar system bodies. The method carries uncertainties and is not yet a galaxy‑wide consensus.
