Title: The Mysterious Origins of a Long-Gone World’s Meteorite
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The planets and dwarf planets we see today in our solar system were born from a disk of material surrounding the Sun around 4.6 billion years ago. Not all of these celestial bodies endured, and a recent study of the meteorite NWA 15915 suggests it came from a planet similar to Mercury in composition, yet distinct from Mercury itself.
These rare meteorites, accounting for only 0.2 percent of all meteorites, offer a unique glimpse into the tumultuous early days of the Solar System. While we now observe a well-organized system of planets circling the Sun, over four billion years ago, chaos reigned as these planets took shape from the Sun’s disk. Earth itself experienced a catastrophic collision with another protoplanet, leaving remnants buried deep in the Earth’s mantle.
Meteorites scattered across our planet hold clues to this chaotic period. An analysis of NWA 15915, a 2.84-kilogram rock discovered in Algeria in 2023, reveals it might be a fragment of a long-lost world that formed in an environment akin to that of Mercury. This new study, led by Jennifer Mitchell from the University of Minnesota, found that the rock did not align with known meteorite groups or planetary bodies.
While the majority of meteorites can be linked to specific parent bodies like the Moon or Mars, outliers like NWA 15915 are rare, making up only 0.2 percent. Mitchell’s team used advanced tools to study the meteorite’s composition, discovering it differed from Mercury’s but had formed in a similarly low-oxygen setting. The team presented these findings at the Lunar and Planetary Sciences Conference in Texas, suggesting a large differentiated body in the inner Solar System.
NWA 15915’s unique mix of magnetic metal-rich minerals and slow cooling rate point to a Mercury-like origin. While finding remnants of ancient worlds on Earth is unusual, it remains possible due to the existence of protoplanets in the early Solar System. Some models speculate on at least 50 to 100 Moon-to-Mars-sized protoplanets, with some merging to form present-day planets while others, like Ceres, Pallas, and Vesta, surviving relatively intact. Pieces of these lost worlds may still exist today, offering insights into our cosmic past.
Mitchell emphasizes that this discovery, found either in clusters or dispersed across the Main Asteroid and Kuiper belts, is a preliminary one. However, it presents a remarkable chance to gain further insights into the ancient worlds of our early Solar System.
