Rare meteorite provides evidence of giant early planet

Key Points:

• Scientists have found definitive evidence of a lost planetary embryo, a massive protoplanet possibly as large as the moon or Mars, which existed about 4.5 billion years ago before being shattered in a collision.
• This discovery is based on the study of the Northwest Africa (NWA) 12774 angrite meteorite, a rare volcanic rock with a unique chemistry that lacks typical silicon dioxide found in terrestrial planets.
• Analysis of aluminum-rich clinopyroxene crystals in the meteorite revealed formation under extremely high pressures, indicating the parent body was at least 1,000 kilometers in radius, much larger than previously assumed for angrite sources.
• The preserved crystal structures suggest the protoplanet could have been even larger, potentially up to 1,800 kilometers or more in radius, comparable to the moon and possibly approaching Mars in size.
• This finding challenges existing models of planetary formation, indicating that early solar system bodies followed distinct evolutionary paths, and suggests that remnants of other unknown protoplanets may still be found among meteorite collections.