Ancient Meteorite Reveals a Forgotten Planet That Existed 4.5 Billion Years Ago
A rare angrite meteorite, Northwest Africa (NWA) 12774, recovered from the Sahara Desert, provides direct evidence of a lost protoplanet at least 1,000 km in radius that existed 4.5 billion years ago. Researchers found high-pressure minerals in the meteorite that could only form deep inside a planetary body, suggesting it rivaled the size of the Moon or Mars before likely being destroyed in a catastrophic collision.
A meteorite discovered in the Sahara Desert has offered the first direct proof of a long-lost planetary body that formed during the solar system’s infancy. The meteorite, Northwest Africa (NWA) 12774, is an angrite—a rare type of volcanic rock formed just 2–3 million years after the solar system’s creation 4.56 billion years ago. Of over 80,000 known meteorites, only 68 are classified as angrites, and their unusual chemistry, including low silica content, has long puzzled scientists. Researchers led by Aaron Bell of the University of Colorado Boulder analyzed NWA 12774 and identified clinopyroxene, a mineral with abnormally high aluminum levels. Modeling showed this mineral could only form under extreme pressures—at least 17.5 kilobars—far exceeding pressures found in small asteroids. The Mariana Trench, Earth’s deepest point, reaches only about 1 kilobar, meaning the angrite’s parent body must have had a radius of at least 1,000 kilometers (621 miles). Further evidence suggests the protoplanet may have been even larger. Crystals within the meteorite retained sharp edges and chemical patterns that likely formed at shallow depths, implying the body had a substantial interior to generate such pressures. If correct, the parent body could have exceeded 1,800 kilometers (1,118 miles) in radius, comparable to the Moon or approaching Mars’ size. The discovery challenges previous assumptions that angrites originated from small asteroids. Instead, the meteorite’s composition points to a distinct evolutionary path for early planetary bodies, separate from Earth and Mars. Researchers speculate the protoplanet may have been shattered in a collision early in solar system history, with its fragments later incorporated into other rocky planets, including Earth. Bell noted that many unstudied meteorites could hold clues to additional lost worlds. The findings, published in *Earth and Planetary Science Letters*, highlight how rare meteorites preserve evidence of the solar system’s violent and dynamic early history.
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