Colorado Researchers Find 1,800-Km Protoplanet From 4.5-Billion-Year-Old Meteorite Evidence
Updated
Updated · starlust.org · Jun 3
Colorado Researchers Find 1,800-Km Protoplanet From 4.5-Billion-Year-Old Meteorite Evidence
3 articles · Updated · starlust.org · Jun 3
Summary
NWA 12774 meteorite data point to a parent body more than 1,800 kilometers in radius, giving researchers what they call the first definitive evidence of a Moon-sized early protoplanet.
17.5 kilobars of pressure were needed to form its aluminum-rich clinopyroxene, far beyond what a small asteroid could generate and implying a planetary-scale object.
Sharp crystal edges and delicate chemical zoning survived in the rock, suggesting the minerals formed near the surface rather than deep inside—requiring an even larger body to create that pressure.
Only 68 of more than 80,000 known meteorites are angrites, and this finding overturns the long-held view that their parent bodies were small asteroids under 200 kilometers in radius.
The team says the object likely was shattered in a catastrophic collision 4.5 billion years ago, hinting that early solar-system planet formation followed multiple pathways and that more lost protoplanets may await discovery.
A Mars-sized world was shattered 4.5 billion years ago. Could its fragments be hiding in plain sight?
How does one lost protoplanet completely upend our understanding of how worlds are born?
Are there other 'ghost planets' from the early solar system still waiting to be discovered?
Discovery of a Moon-Sized Protoplanet in the Early Solar System: Angrite Meteorites Rewrite Planetary Formation History
Overview
Recent research led by Dr. Aaron Bell's team at the University of Colorado Boulder has provided strong evidence for a massive protoplanet in the early solar system, about 4.5 billion years ago. This discovery is based on the unique mineralogy and chemistry of the Northwest Africa (NWA) 12774 angrite meteorite, which is very different from Earth and Mars. Unlike most terrestrial planets, angrites contain very little silica, suggesting their parent body followed a separate evolutionary path. This challenges previous ideas that angrites came from small asteroids, revealing a more complex story of planetary formation.