A meteorite discovered in Northwest Africa is shattering long-held beliefs about the pace of planetary formation in our Solar System, according to new findings.
Scientists say this ancient rock—formed more than 4.56 billion years ago—proves that planet-building processes in the outer reaches of the solar system began just as quickly as they did closer to the Sun.
In a study published in Communications Earth & Environment, researchers analyzed a rare meteorite known as Northwest Africa (NWA) 12264, revealing that the body it originated from—a fully formed protoplanet beyond Jupiter—was already active during the very dawn of the Solar System.
The findings challenge the prevailing assumption that outer Solar System planets formed more slowly due to cooler temperatures and higher ice content and instead suggest that planetesimal formation was a synchronized, system-wide phenomenon.
“This sample, Northwest Africa (NWA) 12264, formed on a first–generation differentiated protoplanet in the outer Solar System,” the researchers write. “It is the oldest magmatic rock from the outer Solar System analyzed thus far and provides crucial empirical constraints on the timing of differentiation in the most ancient protoplanets that formed beyond the snowline.
For decades, the story of how our Solar System formed has included a fundamental split: rocky planets like Earth, Mars, and Venus formed quickly and close to the Sun, while icy giants and their satellites emerged more slowly farther out. This belief was rooted in both astronomical models and chemical data from meteorites. However, the freshly analyzed NWA 12264 meteorite appears to upend that narrative.
The dunite meteorite—a rock type typically found in planetary mantles—contains key isotopic clues indicating it formed on a large, layered protoplanet with a metal core and silicate mantle, much like Earth. Crucially, the radiometric dating of its minerals places its formation just a few million years after the birth of the Solar System itself.
Using high-precision lead-lead (Pb-Pb) and aluminum-magnesium (Al-Mg) dating techniques, scientists determined the age of NWA 12264 to be around 4,569.8 ± 4.6 million years, making it older than any previously studied rock from the outer Solar System.
The aluminum-magnesium method yielded a slightly younger age of 4,564.44 ± 0.30 million years, but both values are significantly earlier than those from other known outer system meteorites.
Even accounting for expected dating discrepancies, researchers say the data from NWA 12264 clearly indicate that its parent body—an ancient, now-shattered protoplanet—must have accumulated, differentiated, and broken apart in rapid succession, likely within the first few million years of the Solar System’s formation.
“These findings push back the earliest known outer Solar System differentiation age by ~2 million years,” the authors note. “These findings support new models and challenge the current paradigm, which posits that protoplanets in the outer Solar System accreted more slowly and underwent differentiation later than their inner Solar System counterparts.”
The meteorite’s origin was traced to the so-called carbonaceous chondrite (CC) reservoir, a region associated with volatile-rich, primitive materials located beyond the water-ice line, also known as the “snowline,” in the solar nebula.
This division has long marked the boundary between the Solar System’s “wet“ and “dry“ regions. Yet, evidence from NWA 12264 suggests that both zones may have undergone rapid evolution in parallel.
The discovery lends support to recent observations of young star systems made by the Atacama Large Millimeter/submillimeter Array (ALMA), where scientists have detected planet-forming rings and gaps distributed throughout distant protoplanetary disks. These structures suggest that planetesimals—small bodies that can grow into full-fledged planets—form simultaneously at multiple distances from their star.
“These data support the view that planetesimal formation at large heliocentric distances may have been common in the early Solar System,“ the study explains,” and could help explain the apparent synchronicity in the accretion and differentiation of inner and outer Solar System bodies.”
The researchers also found chemical and isotopic similarities between NWA 12264 and other rare meteorite groups, such as the Milton pallasite and the South Byron Trio iron meteorites, suggesting that these diverse fragments may all hail from the same ancient planetary body, or at least from neighboring ones formed under similar conditions.
Although NWA 12264 is currently the only known silicate-dominated sample of its kind, scientists believe other related fragments may already exist in collections or await discovery. One candidate, NWA 7822, shares some structural similarities but differs chemically, suggesting the presence of a second, distinctly differentiated body in the outer Solar System.
The rapid formation of such bodies, especially those large enough to undergo internal melting and layering, requires a particular set of conditions. In this case, the parent body of NWA 12264 likely had low water content, which would have reduced heat dissipation and allowed for earlier differentiation—a contrast to the typical assumptions about outer Solar System materials.
Beyond revising Solar System timelines, the study has broader implications for how we interpret exoplanetary systems. Suppose our Solar System’s inner and outer regions evolved simultaneously. In that case, the same might be true in other star systems, meaning habitable planets could form faster and more widely than once imagined.
Ultimately, ancient meteorites like NWA 12264 remain some of the most reliable time capsules, holding the keys to understanding the mysterious and turbulent birth of worlds.
“NWA 12264 stands as a single representative of a former outer Solar System planetesimal’s mantle,” the researchers write. “[However,] this study indicates that protoplanet-scale differentiation processes in the outer carbonaceous region may be more prevalent than previous evidence suggested.”
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com