This meteorite could be a relic from a ‘lost world’
Researchers analyzing the 4.56-billion-year-old angrite meteorite NWA 12774, found in the Sahara Desert in 2019, determined it likely originated from a massive, moon-sized protoplanet that formed within four million years of the solar system’s creation. The meteorite’s high-pressure clinopyroxene crystals suggest it formed under extreme conditions, challenging previous assumptions that angrites came from smaller asteroidal bodies.
A team of researchers has identified that the meteorite NWA 12774, recovered from the Sahara Desert in 2019, likely originated from a long-lost protoplanet during the solar system’s earliest epochs. The meteorite, an angrite—a rare class of volcanic rock—dates back to just a few million years after the solar system formed 4.56 billion years ago. Of the approximately 80,000 meteorites cataloged on Earth, fewer than 70 are angrites, making this discovery particularly significant. The study, published in *Earth and Planetary Science Letters*, analyzed the meteorite’s clinopyroxene crystals, which contained unusually high levels of aluminum. This indicated the crystals formed under extreme pressure, far greater than previously assumed for angrites. Lead author Aaron Bell, an experimental petrologist at the University of Colorado Boulder, developed a computational geobarometer to estimate the parent body’s conditions. The model revealed the clinopyroxene formed at a pressure of at least 17.5 kilobars—over 15 times the pressure at Earth’s deepest ocean trenches—suggesting the meteorite came from a massive protoplanet, possibly moon-sized. Previously, scientists believed angrites originated from smaller asteroidal bodies due to lack of evidence supporting larger parent worlds. However, the new findings challenge this assumption, indicating that within four million years of the solar system’s formation, planetary bodies of significant size had already formed. Francois Tissot, a geochemistry researcher at the California Institute of Technology, noted the rapid formation timescale, emphasizing the meteorite’s implications for understanding early cosmic history. The discovery reshapes theories about the solar system’s early development, revealing that large protoplanets existed before many of today’s celestial bodies. The study’s methods, combining mineral analysis with computational modeling, provide a new approach to tracing the origins of ancient meteorites. This research could offer deeper insights into the violent and dynamic processes that shaped the solar system’s infancy.
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