Sahara meteorite shows evidence of lost moon‑size world

A meteorite discovered in the Sahara Desert contains the first definitive evidence of a large, lost world that existed in the early solar system, according to new research. The study indicates this protoplanet, potentially as large as Earth's moon or Mars, was destroyed more than four billion years ago.

The meteorite, known as Northwest Africa 12774, was found in 2019 and weighs roughly one pound. Scientists classify it as an angrite, a rare type of meteorite that ranks among the oldest volcanic rocks in the solar system. Of the more than 80,000 meteorites cataloged on Earth, only 68 are confirmed angrites.

Researchers led by geoscientist Aaron Bell of the University of Colorado Boulder analyzed the sample and identified crystals of a mineral called clinopyroxene that were exceptionally rich in aluminum. This chemical signature indicates the rock formed under immense pressure. The team's analysis, published in the journal Earth and Planetary Science Letters, calculated that forming these crystals required pressures of at least 17.5 kilobars—more than 17 times the pressure found at the bottom of the Mariana Trench, the deepest point on Earth.

Such extreme conditions could not have...