🪐 A Rare Meteorite May Preserve Evidence of a Lost World from the Dawn of the Solar System
Scientists at the University of Colorado Boulder have uncovered what may be the strongest evidence yet for a vanished protoplanet — a planetary embryo that once orbited the young Sun more than 4.5 billion years ago before being destroyed in a catastrophic collision.
The clue comes from an unusual meteorite known as Northwest Africa (NWA) 12774, discovered in the Sahara Desert. It belongs to the angrites, one of the rarest meteorite groups ever found. Out of more than 80,000 known meteorites, only a few dozen are classified as angrites. These rocks formed during the earliest stages of solar system history, just a few million years after the Sun was born.
What makes NWA 12774 remarkable is its mineral chemistry. Researchers found clinopyroxene crystals enriched in aluminum — a signature that indicates formation under enormous pressure. Their calculations suggest pressures exceeding 17.5 kilobars, more than 17 times greater than the pressure at the bottom of the Mariana Trench.
Such conditions could not have existed inside a small asteroid.
The results imply that the meteorite’s parent body had a radius of at least 1,000 km. Because the crystals preserve delicate structures that would likely not survive deep burial, the original world may have been much larger — potentially approaching the size of the Moon and perhaps even Mars.
🔹 Evidence points to a planetary embryo at least 1,000 km in radius
🔹 Formation pressures exceeded 17.5 kilobars
🔹 Its composition differs significantly from Earth and Mars
🔹 It may represent a previously unknown pathway of planetary evolution
🔹 Fragments of similar lost worlds could still be hiding in meteorite collections
The study suggests that the early solar system was far more diverse than previously thought. Many planetary embryos likely formed, collided, merged, or were destroyed before the planets we know today emerged.
How many lost worlds helped build the solar system we live in?
📄 Original paper (Earth and Planetary Science Letters) · ScienceDaily
#astronomy #space #meteorite #planetaryscience #solarsystem
Scientists at the University of Colorado Boulder have uncovered what may be the strongest evidence yet for a vanished protoplanet — a planetary embryo that once orbited the young Sun more than 4.5 billion years ago before being destroyed in a catastrophic collision.
The clue comes from an unusual meteorite known as Northwest Africa (NWA) 12774, discovered in the Sahara Desert. It belongs to the angrites, one of the rarest meteorite groups ever found. Out of more than 80,000 known meteorites, only a few dozen are classified as angrites. These rocks formed during the earliest stages of solar system history, just a few million years after the Sun was born.
What makes NWA 12774 remarkable is its mineral chemistry. Researchers found clinopyroxene crystals enriched in aluminum — a signature that indicates formation under enormous pressure. Their calculations suggest pressures exceeding 17.5 kilobars, more than 17 times greater than the pressure at the bottom of the Mariana Trench.
Such conditions could not have existed inside a small asteroid.
The results imply that the meteorite’s parent body had a radius of at least 1,000 km. Because the crystals preserve delicate structures that would likely not survive deep burial, the original world may have been much larger — potentially approaching the size of the Moon and perhaps even Mars.
🔹 Evidence points to a planetary embryo at least 1,000 km in radius
🔹 Formation pressures exceeded 17.5 kilobars
🔹 Its composition differs significantly from Earth and Mars
🔹 It may represent a previously unknown pathway of planetary evolution
🔹 Fragments of similar lost worlds could still be hiding in meteorite collections
The study suggests that the early solar system was far more diverse than previously thought. Many planetary embryos likely formed, collided, merged, or were destroyed before the planets we know today emerged.
How many lost worlds helped build the solar system we live in?
📄 Original paper (Earth and Planetary Science Letters) · ScienceDaily
#astronomy #space #meteorite #planetaryscience #solarsystem
ScienceDaily
Meteorite reveals a lost moon-sized world from the dawn of the solar system
A rare meteorite has revealed evidence of a massive lost world that once orbited the young Sun before being destroyed in a catastrophic collision. The discovery suggests some early planets formed from dramatically different materials than Earth and Mars,…
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🪐 A Wobbling “Peanut” Asteroid May Still Carry Traces of Ancient Water
NASA’s Lucy mission has revealed one of the strangest small worlds ever seen up close: asteroid Donaldjohanson — a young, peanut-shaped rock in the main asteroid belt that tumbles through space and still preserves chemical hints of liquid water from its distant past.
Lucy flew past Donaldjohanson on April 20, 2025, at about 30,000 mph, coming within just 650 miles of the asteroid. The encounter was meant partly as a rehearsal before Lucy reaches Jupiter’s Trojan asteroids in 2027. Instead, it became a science story of its own.
Donaldjohanson does not rotate like a simple spinning rock. Data from Lucy show that it tumbles end-over-end once every 10.5 Earth days, while also wobbling around its long axis every 26.5 days — more like an unstable top than a normal asteroid.
Its shape is just as unusual. Donaldjohanson is a contact binary: two lobes joined by a narrow neck, giving it a cosmic peanut-like form. Scientists think it formed about 155 million years ago, when fragments from a violent collision gently came back together under their own gravity.
Since then, sunlight has been slowly reshaping it. Through the YORP effect — a tiny torque caused when sun-warmed surfaces radiate heat back into space — Donaldjohanson’s spin appears to have slowed by at least a factor of 10 over the last 20–60 million years. As the rotation changed, loose material likely slid down its slopes, softening craters and reshaping the surface.
But the most intriguing clue came from Lucy’s infrared data: iron-rich clay minerals on the surface. These minerals form in the presence of liquid water, meaning Donaldjohanson’s parent body once experienced aqueous alteration. But unlike Bennu and Ryugu, which contain magnesium-rich clays suggesting longer exposure to water, Donaldjohanson’s chemistry points to a much shorter episode.
🔹 Donaldjohanson is a bilobed “contact binary” asteroid
🔹 It tumbles on two axes, with rotation periods of 10.5 and 26.5 days
🔹 Its current body likely formed around 155 million years ago
🔹 Sunlight gradually slowed its spin through the YORP effect
🔹 Iron-rich clays suggest liquid water was present — but only briefly
🔹 The flyby was also a successful rehearsal for Lucy’s Trojan asteroid encounters, beginning with Eurybates in August 2027
Important caveat: this was a fast flyby, not an orbital mission or a sample return. Lucy measured the surface remotely; the asteroid’s interior remains unknown.
Still, Donaldjohanson matters because it gives scientists a rare comparison point. Bennu and Ryugu are near-Earth asteroids with long migration histories. Donaldjohanson is a much younger main-belt object that stayed closer to its birthplace. Its strange shape, unstable spin, and brief water history offer a fresh clue to how small bodies evolved — and how water-rich material may have moved through the early Solar System.
📄 Sources: https://www.science.org/doi/10.1126/science.aec0503
#NASA #LucyMission #Asteroid #PlanetaryScience #SolarSystem
NASA’s Lucy mission has revealed one of the strangest small worlds ever seen up close: asteroid Donaldjohanson — a young, peanut-shaped rock in the main asteroid belt that tumbles through space and still preserves chemical hints of liquid water from its distant past.
Lucy flew past Donaldjohanson on April 20, 2025, at about 30,000 mph, coming within just 650 miles of the asteroid. The encounter was meant partly as a rehearsal before Lucy reaches Jupiter’s Trojan asteroids in 2027. Instead, it became a science story of its own.
Donaldjohanson does not rotate like a simple spinning rock. Data from Lucy show that it tumbles end-over-end once every 10.5 Earth days, while also wobbling around its long axis every 26.5 days — more like an unstable top than a normal asteroid.
Its shape is just as unusual. Donaldjohanson is a contact binary: two lobes joined by a narrow neck, giving it a cosmic peanut-like form. Scientists think it formed about 155 million years ago, when fragments from a violent collision gently came back together under their own gravity.
Since then, sunlight has been slowly reshaping it. Through the YORP effect — a tiny torque caused when sun-warmed surfaces radiate heat back into space — Donaldjohanson’s spin appears to have slowed by at least a factor of 10 over the last 20–60 million years. As the rotation changed, loose material likely slid down its slopes, softening craters and reshaping the surface.
But the most intriguing clue came from Lucy’s infrared data: iron-rich clay minerals on the surface. These minerals form in the presence of liquid water, meaning Donaldjohanson’s parent body once experienced aqueous alteration. But unlike Bennu and Ryugu, which contain magnesium-rich clays suggesting longer exposure to water, Donaldjohanson’s chemistry points to a much shorter episode.
🔹 Donaldjohanson is a bilobed “contact binary” asteroid
🔹 It tumbles on two axes, with rotation periods of 10.5 and 26.5 days
🔹 Its current body likely formed around 155 million years ago
🔹 Sunlight gradually slowed its spin through the YORP effect
🔹 Iron-rich clays suggest liquid water was present — but only briefly
🔹 The flyby was also a successful rehearsal for Lucy’s Trojan asteroid encounters, beginning with Eurybates in August 2027
Important caveat: this was a fast flyby, not an orbital mission or a sample return. Lucy measured the surface remotely; the asteroid’s interior remains unknown.
Still, Donaldjohanson matters because it gives scientists a rare comparison point. Bennu and Ryugu are near-Earth asteroids with long migration histories. Donaldjohanson is a much younger main-belt object that stayed closer to its birthplace. Its strange shape, unstable spin, and brief water history offer a fresh clue to how small bodies evolved — and how water-rich material may have moved through the early Solar System.
📄 Sources: https://www.science.org/doi/10.1126/science.aec0503
#NASA #LucyMission #Asteroid #PlanetaryScience #SolarSystem
Science
The Lucy flyby of (52246) Donaldjohanson: A bilobed asteroid with tumbling rotation
The main belt asteroid (52246) Donaldjohanson (DJ) is a likely member of the Erigone asteroid family. This implies that DJ is a fragment of a larger parent body that was destroyed in a collision about 155 million years ago. We report observations taken ...
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