A rare meteorite found in the Sahara Desert has revealed evidence of a giant ancient world that once existed in our solar system but later disappeared.
Scientists believe this lost world formed about 4.5 billion years ago, during the early days of the solar system.
It may have been as large as the Moon or even approached the size of Mars before being destroyed in a massive collision.
The findings were published in the journal Earth and Planetary Science Letters.
The discovery came from studying a meteorite called Northwest Africa (NWA) 12774.
This meteorite belongs to a very rare group known as angrites. Angrites are among the oldest volcanic rocks ever found and formed only a few million years after the solar system was born around 4.56 billion years ago.
They are extremely uncommon. Out of more than 80,000 meteorites discovered on Earth, only 68 are known to be angrites.
For years, scientists believed angrites came from a relatively small asteroid. This idea was based on their unusual chemistry. Unlike Earth, Mars and most rocky planets, angrites contain very little silica, a major ingredient in the rocks that make up many planets.
However, a closer look at NWA 12774 told a different story.
Researchers found that the meteorite contains a mineral called clinopyroxene. This mineral is common in Earth’s crust and mantle, but the version found in the meteorite contained an unusually high amount of aluminum. According to the research team, this is a sign that the rock formed under extremely high pressure deep inside a planetary body.
The scientists calculated the pressure needed to create the mineral. They found it would require at least 17.5 kilobars of pressure. For comparison, the pressure at the bottom of the Mariana Trench, the deepest part of Earth’s oceans, is only about 1 kilobar.
A small asteroid simply could not generate that much pressure. Instead, the calculations suggest that the parent body of the meteorite must have had a radius of at least 1,000 kilometers.
The evidence became even more surprising when researchers examined the crystals inside the meteorite. The crystals still had sharp edges and delicate chemical features that would normally be destroyed if they had formed deep underground. This suggests the crystals likely formed closer to the surface.
If that is true, the original world must have been even larger—possibly more than 1,800 kilometers in radius. That would make it comparable in size to Earth’s Moon and perhaps not far from Mars.
Scientists still do not know exactly what happened to this ancient world. It may have been shattered during one of the violent collisions that were common in the young solar system. Its fragments could later have become part of other planets, including Earth.
The discovery suggests that many early protoplanets once existed and followed different paths of development. Researchers believe more clues may be hiding in meteorite collections around the world, waiting to reveal other lost worlds from the solar system’s distant past.
