Scientists from the University of Colorado Boulder have presented compelling evidence for the existence of a large planet in the early Solar System that was completely destroyed billions of years ago. Its remains likely continue to fall to Earth in the form of rare meteorites.

The study was published in the journal Earth and Planetary Science Letters (EPSL).

Angrites as the key to the mystery

The main object of study was the meteorite NWA 12774, belonging to the angrite class. These meteorites stand out among all other rocks for their extremely unusual chemical composition: very low sodium content combined with elevated levels of calcium and aluminum.

Previously, it was believed that the parent body of angrites (APT) was relatively small — about the size of a large asteroid. However, a detailed analysis of NWA 12774 has completely changed this picture.

What the analysis showed

Researchers led by Aaron Bell conducted a comprehensive study of the meteorite's mineral composition, texture, and thermal history. The data obtained indicate that the rock formed under conditions of a large differentiated planetary body — with a metallic core, a silicate mantle, and active volcanism on the surface.

Thermodynamic modeling allowed the researchers to estimate APT's radius in the range of 1,000 to 3,300 kilometers. This is comparable to the size of Mars.

Fate of the planet

According to the authors, the planet was destroyed as a result of powerful collisions during the formation of the Solar System about 4.5 billion years ago. The debris scattered throughout the asteroid belt, and some of it eventually reached Earth in the form of angrites. All known angrites to date are likely fragments of the same "lost world."

Significance of the discovery

The discovery helps solve one of the major mysteries — the problem of missing mass. Calculations suggest that there should have been significantly more large planetesimals in the early Solar System than we observe today. The destruction of bodies such as APT could have been the source of a significant portion of this "vanished" matter.

Furthermore, the study indirectly confirms that planetary destruction and material recycling processes were far more intense than previously thought.

In brief

Scientists have determined that the meteorite NWA 12774 is a fragment of a large destroyed planet the size of Mars that existed in the early Solar System. Its radius could have reached 3,300 km. The destruction of the planet about 4.5 billion years ago explains the unique chemical composition of angrites and helps us understand where a significant portion of the Solar System's "missing" ordinary matter might have gone. The discovery significantly changes our understanding of the dynamics of the Solar System's formation.