A meteorite found in the Sahara desert could be evidence of the existence of an ancient Moon, now lost
The rock we are talking about, which weighs about half a kilo, was found in the Sahara in 2019 and named Nwa 12774. Over time, it has been observed by scientists to reveal its mineral characteristics. It contains the first evidence of the existence of a now-lost celestial body, which may have rivaled the Moon in size and existed only a few million years after the formation of the solar system 4.5 billion years ago. It has been classified as Angrite, a type of meteorite that is among the oldest volcanic rocks in the solar system. This is something very rare: only 68 of the over 80,000 meteorites recovered on Earth are angrites. It retains an unusual chemical signature that suggests that some of the solar system’s early worlds developed differently than other rocky planets.
Aaron Bell, geoscientist at the University of Colorado Boulder and author of the study, said: «The materials that formed the parent body of Angrite are different from the ingredients of Earth and Marsthese meteorites preserved evidence of a completely different path by which the first planets developed.” By measuring the tiny radioactive elements within them, which act like natural clocks, scientists know that angrites formed close to the Sun when it was young more than 4.5 billion years ago. Therefore, according to NASA, Nwa 12774 holds precious clues about how planets formed and evolved. What makes them particularly enigmatic is their chemical composition.
A rock created under enormous pressure
Unlike Earth, Mars, and most other rocky worlds, Angrites contain very little silica, the main component of the sand we knowfundamental in planetary crusts throughout the solar system. Because of this unusual composition, scientists have long assumed that it originated from a relatively small asteroid. By analyzing Nwa 12774, Bell and his colleagues identified crystals of a mineral called clinopyroxeneexceptionally rich in aluminum, an unmistakable sign that the rock was formed under immense pressure.
By reconstructing these conditions, Bell’s team found that the mineral required pressure 17 times higher than that existing at the bottom of the Mariana Trench, the deepest point on Earth. These extreme conditions could not exist inside a small asteroidso the parent body must have been much larger. Crystals within the space rock also retained characteristics such as sharp edges and chemical patterns that scientists believe would have been erased if they had spent long periods deep in a hot planetary interior. These clues suggest that the minerals formed at relatively shallow depths, meaning that the parent body would have had to be substantially larger to generate the same pressures near its surface.
Hypotheses on the ancient Moon
This hypothesis leads one to think that the world is lost it may have exceeded 1,800 kilometers in radiusbeing comparable in size to the Earth’s Moon (1,774 km). “It’s incredible to think that such a large world once existed,” Bell said in the statement, “we only know of its existence because fragments of it landed on Earth, and we don’t know what happened to this ancient world.” One possibility, according to the researchers, is that it was destroyed in one of the violent collisions reshaping the young solar system, with fragments like Nwa 12774 later incorporated into other rocky planets, including Earth. And it may well be that there is other, hitherto overlooked, evidence for the existence of these lost worlds.
