Researchers Stumble Upon a Meteorite in Antarctica That Holds a 4.5 Billion-Year-Old Secret

Celestial bodies such as meteorites have covered a distance of lightyears across the universe before crashing into Earth. This means that they also carry secrets of the cosmos dating back millennia. When scientists found one such meteorite embedded in the thick ice of Antarctica, they unlocked a time capsule carrying insights about the universe.

In a 2019 study published in Nature Astronomy, researchers documented the discovery of this celestial relic, which is probably older than the Sun. It carried a tiny blue-and-red grain, which is the speck of a star that once exploded. Researchers noted that the grain measured “only 1/25,000 of an inch” and was shaped like a croissant. They proposed that the mix of materials contained in the grain was the same as the one behind the formation of the Sun and some of the planets.

"As actual dust from stars, such presolar grains give us insight into the building blocks from which our solar system formed. They also provide us with a direct snapshot of the conditions in a star at the time when this grain was formed," Pierre Haenecour, lead author of the paper, said in a press release. They estimated that before hurtling towards Earth’s solar system, the grain, then a full-fledged star, survived 4.5 billion years as it traveled through space. Using different types of microscopes, the team analyzed the grain and found that it was made of graphite, a form of carbon, and silicate, a salt made of silicon and oxygen. This composition indicated that the grain likely came from a star explosion called a “nova.”

A nova explosion is an interaction between a red giant star and a white dwarf star. A white dwarf is a star that has used up most of its nuclear fuel. So it feeds off other stars, siphoning off material from their bloated bodies. Slowly, the material from the red giant stars starts disintegrating and falling on the surface of the white dwarf. This bulk of material accumulates at the white dwarf’s surface, building a layer of hydrogen at its rim. As this layer becomes denser and hotter, the white dwarf reignites itself, spewing the starry material into its celestial neighborhood.

LAP-149, the ancient grain discovered in Antarctica, was probably formed in the same way before making its way to Earth’s solar system. Its chemical composition could offer hints about the evolution of the universe itself, which is fascinating. “Although their parent stars no longer exist, the isotopic and chemical compositions and microstructure of individual stardust grains identified in meteorites provide unique constraints on dust formation and thermodynamic conditions in stellar outflows,” the researchers explained.

Haenecour said that this tiny grain offered glimpses “into a process we could never witness on Earth.” Another remarkable thing about this grain is that it survived. It made its way to Earth after getting embedded into a meteorite lying in Antarctic ice. Given the violent nature of space, the grain could have easily been destroyed. It could have been blasted by an exploding star or caught in a collapsing nebula, or baked into an asteroid. But instead, it survived and reached Earth.