Scientists have discovered that a meteorite that fell in Australia in 1969 contains grains of stardust that formed before our Solar System existed. These grains are the oldest solid material ever found on Earth, and they reveal secrets about the origins of the universe.

The meteorite in question is called Murchison, and is around 4.6 billion years old. It is a type of space rock known as carbonaceous chondrite, which contains organic compounds and water. These meteorites are considered the building blocks of planets, and may have brought life to Earth.

But what's most impressive about Murchison are the grains of stardust it carries. These grains are called pre-solar grains because they formed in stars that existed long before the Sun was born. They are composed of heavy elements, such as silicon, carbon and aluminum, which were produced in reactions that occur inside stars.

When stars die, they launch these grains into space, where they can be incorporated into new stars, planets, moons and meteorites. Pre-solar grains are very rare, and represent only a small fraction of the mass of meteorites. Therefore, they are difficult to identify and analyze.

A team of researchers from the United States and Switzerland managed to isolate 40 pre-solar grains from the Murchison meteorite, using a technique that involves dissolving the rock in acid. They then measured the age of the grains, using a method that relies on exposure to cosmic rays in space.

Cosmic rays are high-energy particles that travel throughout the galaxy and interact with matter. The longer the grains are exposed to cosmic rays, the more they accumulate new elements, such as neon-21. By measuring the amount of these elements in grains, researchers can estimate how long they traveled through space before arriving on Earth.

The results were surprising. Murchison's pre-solar grains are between 5 and 7 billion years old, making them much older than the meteorite itself, and the Earth, which is around 4.5 billion years old. Some of the grains are the oldest ever discovered, and date back to a time when our galaxy was still forming.

These grains bear witness to an incredible cosmic story, and can help us better understand how stars form and evolve, and how they produce the elements that make up everything that exists. They can also give us clues about the conditions of interstellar space, and about the origin of the Solar System.

The Murchison meteorite is a scientific treasure, containing stardust that shone long before us. He shows us that we are part of an ancient and wonderful universe, and that our story begins far beyond Earth.

https://m.stacker.news/30982