The oldest of 40 tiny dust grains trapped inside the meteorite fragments retrieved around the town of Murchison in Victoria state dated from about 7 billion years ago, about 2.5 billion years before the sun, Earth and rest of our solar system formed, the researchers said. "Despite having worked on the Murchison meteorite and presolar grains for almost 20 years, I still am fascinated that we can study the history of our galaxy with a rock," Heck added. Dust grains floating through space get bombarded by high-energy particles called cosmic rays. Scientists previously had found a presolar grain in the Murchison meteorite that was about 5.5 billion years old, until now the oldest-known solid material on Earth. The oldest-known minerals that formed on Earth are found in rock from Australia's Jack Hills that formed 4.4 billion years ago, 100 million years after the planet formed.

Source: Dhaka Tribune January 14, 2020 06:56 UTC