Ancient Meteorite Reveals a Lost Moon-Sized World
Scientists discovered a remarkable one-pound rock in the Sahara Desert. They recovered the meteorite, known as Northwest Africa 12774, in 2019. This rare angrite belongs to one of the oldest volcanic rock classes in science.
New research shows that the meteorite came from a moon-sized planet. This world once orbited our young Sun about 4.5 billion years ago. Later, it vanished completely.
Pressure, Crystals, and a Vanished World
Aaron Bell from the University of Colorado Boulder led the study. His team published the findings in the journal Earth and Planetary Science Letters.
The researchers found a key clue inside the meteorite. Clinopyroxene crystals inside it contain unusually high levels of aluminum. These crystals formed under extreme pressure of at least 17.5 kilobars.
Such pressure greatly exceeds what any small asteroid could create. Moreover, the crystals kept their sharp edges and delicate chemical patterns. This evidence points to formation at shallow depths.
For such high pressure to exist near the surface, the parent body had to be enormous. Therefore, the team concluded that the lost world measured over 1,800 kilometers in radius. It rivaled the size of Earth’s Moon.
A Different Blueprint for Early Planets
Angrites differ chemically from most rocky planets. They contain almost no silica, a common mineral elsewhere.
For years, scientists believed these rocks came from small asteroids with radii under 200 kilometers. However, Northwest Africa 12774 completely challenges that view.
The lost world followed a unique path of development. It likely ended in a catastrophic collision. As Bell noted, many unexamined meteorites still rest in collections worldwide.
Consequently, more protoplanets may wait to be discovered through future studies.
This finding reshapes our understanding of the early Solar System. It highlights how diverse and dynamic planet formation was billions of years ago.