We only know it existed because fragments fell to Earth
Un fragmento de roca caído en el Sáhara en 2019 guarda en su interior la memoria de un mundo que ya no existe. Científicos de la Universidad de Colorado Boulder han determinado que la meteorita Northwest Africa 12774, de 4.560 millones de años de antigüedad, proviene de un planeta del tamaño de Marte que fue destruido en los violentos albores del sistema solar. Su composición mineral, imposible de forjar sin presiones extremas, obliga a reescribir los modelos que explicaban cómo nació el vecindario cósmico que habitamos.
- Una roca aparentemente ordinaria del desierto resultó contener minerales que solo pueden formarse bajo presiones 17 veces superiores a las del punto más profundo de los océanos terrestres.
- El hallazgo sacude décadas de consenso científico: se asumía que este tipo de meteoritas procedían de pequeños asteroides, no de planetas completos.
- Las simulaciones por ordenador apuntan a un cuerpo con un radio de entre 1.000 y 3.300 kilómetros, dimensiones propias de un planeta comparable a Marte que hoy ha desaparecido por completo.
- La colisión catastrófica que destruyó ese mundo sugiere que el sistema solar primitivo estaba mucho más poblado y era más violento de lo que los modelos actuales contemplan.
- Un único fragmento superviviente, cruzando el vacío durante miles de millones de años, ha llegado a los laboratorios como testigo silencioso de una destrucción planetaria a escala colosal.
En 2019, una pequeña roca aterrizó en el Sáhara sin llamar la atención. Cuando los científicos la analizaron en detalle, descubrieron que la meteorita Northwest Africa 12774, con 4.560 millones de años de antigüedad, no procedía de un asteroide cualquiera, sino de los restos de un planeta del tamaño de Marte que fue destruido en los primeros tiempos del sistema solar.
La clave estaba en su composición. La roca pertenece a una familia rarísima de meteoritas llamadas angritas —apenas 68 catalogadas entre 80.000 fragmentos espaciales conocidos— y en su interior se encontró clinopiroxeno enriquecido con aluminio, un mineral que solo puede formarse bajo presiones aplastantes, propias de las profundidades del manto o la corteza de un planeta. Para dar escala: la fosa de las Marianas experimenta alrededor de un kilobar; esta roca soportó al menos 17,5.
Investigadores de la Universidad de Colorado Boulder introdujeron estos datos en simulaciones de mecánica celeste y obtuvieron una conclusión sorprendente: el cuerpo original tenía un radio de entre 1.000 y 3.300 kilómetros, lo que lo sitúa en la categoría de planeta. El investigador Aaron Bell lo resumió con claridad: solo sabemos que existió porque algunos de sus fragmentos cayeron a la Tierra.
Ese mundo antiguo acabó destruido en una colisión con otro cuerpo masivo. Sus restos se dispersaron por el espacio, y uno de ellos sobrevivió el viaje hasta llegar a nuestros laboratorios. El descubrimiento, publicado en Earth and Planetary Science Letters, no solo rescata la memoria de un planeta perdido; también sugiere que el sistema solar primitivo fue un lugar mucho más caótico y violento de lo que se creía, poblado por mundos gigantes que ya no existen.
In 2019, a small rock fell to Earth in the Sahara Desert. It was unremarkable to look at—just another meteorite among thousands that strike the planet each year. But when scientists began to examine it closely, they found something that rewrote the early history of our solar system. The meteorite, officially named Northwest Africa 12774, is 4.56 billion years old, a fragment from the violent dawn of planetary formation. Its chemical composition told a story that had been hidden for eons: somewhere in the chaos of the young solar system, a planet the size of Mars once existed. Then it was destroyed.
The rock belongs to a rare family of meteorites called angritas, volcanic stones so scarce that only 68 have ever been cataloged among the roughly 80,000 space fragments known to science. For decades, astronomers assumed these meteorites came from small asteroids, bodies no larger than 200 kilometers across. But the analysis published in Earth and Planetary Science Letters revealed something unexpected. Buried within the sample was a mineral called clinopyroxeno enriched with aluminum—a compound that can only form under crushing pressure, the kind found deep within a planet's mantle or crust.
Using computer simulations, researchers at the University of Colorado Boulder calculated the pressures required to create this mineral structure. The rock had endured at least 17.5 kilobars of pressure—a figure almost incomprehensible in human terms. To put it in perspective, the deepest point in Earth's oceans, the Mariana Trench nearly 11 kilometers down, experiences only about one kilobar. The crystal shapes themselves offered another clue: their sharp, angular edges indicated rapid cooling, which meant they formed near the surface or shallow regions of their parent body. If such extreme pressures existed at the surface, the interior must have been far more violent still.
When the team ran the numbers through the laws of celestial mechanics, they arrived at a startling conclusion. The original body from which this fragment came had a radius between 1,000 and 3,300 kilometers—dimensions that place it squarely in the category of a full-fledged planet, comparable to Mars. Aaron Bell, one of the researchers, reflected on the implications: "It's incredible to think that such a massive world once existed. We only know about it because some of its fragments fell to Earth. These meteorites preserve evidence of a completely different pathway through which the earliest planets developed."
The fate of this ancient world was violent. Somewhere in the turbulent early solar system, this Mars-sized planet collided with another massive body and shattered into fragments. Those pieces scattered across space, and one of them—the meteorite now resting in laboratories—eventually found its way to Earth, crossing the void and surviving the passage through our atmosphere. The discovery challenges the conventional understanding of how our solar system took shape. It suggests that the early solar system was far more crowded and chaotic than previously thought, populated by giant worlds that no longer exist. This meteorite is not just a rock; it is a messenger from a lost world, carrying proof that planetary collisions on a catastrophic scale were part of the ordinary process of creation.
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It's incredible to think that such a massive world once existed. We only know about it because some of its fragments fell to Earth.— Aaron Bell, University of Colorado Boulder researcher
A Conversa do Hearth Outra perspectiva sobre a história
Why does this one meteorite matter so much? We find space rocks all the time.
Because this one carries a signature of extreme pressure—the kind that only exists deep inside a planet. Most meteorites come from asteroids, which are small. This one came from something massive.
How can you tell the difference just by looking at minerals?
The aluminum-enriched crystal structure couldn't form unless it was squeezed under crushing weight. It's like finding a fossil that could only have been made in a specific environment. The mineral itself is the evidence.
So you're saying a Mars-sized planet just... vanished?
Not vanished. Destroyed. Smashed into another body in the early solar system. This fragment is all that survived to tell us it existed.
Does this change how we think about Earth's origins?
Fundamentally. It means the young solar system was far more violent and crowded than we thought. Planets the size of Mars were being obliterated. It reshapes the entire timeline of how worlds form and die.
Could something like that happen again?
Not now. The solar system has settled. But in those first few million years, chaos was the rule.