A remarkable meteorite discovered in the Sahara Desert may provide the first evidence of a missing planet that once rivaled the size of the moon. Known as Northwest Africa (NWA) 12774, this meteorite was recovered in 2019 and weighs approximately one pound (454 grams). Recent research indicates that NWA 12774 could offer insights into the early solar system, which formed around 4.5 billion years ago.
Sahara Desert Meteorite Reveals Historical Secrets
Scientists categorize NWA 12774 as an angrite, a rare type of meteorite recognized as one of the oldest volcanic rocks in the solar system. This particular specimen harbors a unique chemical signature, suggesting that early planetary formation varied significantly from the processes that shaped Earth and Mars.
Insights from the Study
Lead researcher Aaron Bell, a geoscientist at the University of Colorado Boulder, highlighted that “the materials that formed the angrite parent body are fundamentally different from the ingredients of Earth and Mars.” This divergence implies an alternative developmental pathway for early planets, which angrites capture as they formed alongside the young sun.
Through the measurement of tiny radioactive elements within the angrites, scientists can timestamp their formation, learning that they originated more than 4.5 billion years ago. Despite being exceptionally rare — only 68 of over 80,000 meteorites recovered on Earth are classified as angrites — they hold invaluable clues to planetary formation.
Unusual Composition of Angrites
Angrites stand out due to their notably low silica levels, a common component in the crusts of rocky planets. This distinct chemistry led to prior assumptions that they originated from smaller asteroids. However, during their analysis of NWA 12774, Bell and his team discovered clinopyroxene crystals rich in aluminum, indicating that the rock formed under extreme pressure conditions.
- Pressures required: At least 17.5 kilobars
- Comparison: Over 17 times the pressure at the Mariana Trench’s bottom
- Implied size of the parent body: Exceeded 1,118 miles (1,800 kilometers) in radius
These findings imply that the parent body likely had to be significantly larger than previously assumed to generate such pressures at its surface. Based on this evidence, researchers speculate that this lost world could be comparable in size to Earth’s moon or even Mars.
Future Research Directions
While the fate of this ancient world remains uncertain, researchers propose that it may have been obliterated during violent collisions that characterized the early solar system. Fragments like NWA 12774 could have later integrated into other rocky planets, including Earth.
Bell also noted that numerous meteorites remain unexamined. Thus, more evidence of these ancient protoplanets could still be undiscovered within collections and awaiting thorough analysis. The study detailing these findings has been published in the journal Earth and Planetary Science Letters.
