Topic: Space

Scientists found evidence of a massive world that existed 4.5 billion years ago. A rare meteorite holds clues to this lost world.

More than 4.5 billion years ago, a huge world traveled around the young Sun before it was shattered into pieces. Scientists have now found the first direct evidence that this long-lost planetary embryo existed. The discovery points to a type of planetary evolution unlike anything previously recognized.

Aaron Bell, an assistant research professor at the University of Colorado Boulder, said, "It's incredible to think there was once a world this large." The breakthrough came from a meteorite discovered in the Sahara Desert called Northwest Africa (NWA) 12774, an angrite meteorite. Angrites are among the oldest volcanic rocks known in the solar system.

The team identified clinopyroxene, a mineral commonly found in Earth's crust and mantle, in this meteorite. The clinopyroxene contained exceptionally high levels of aluminum, which indicated that it formed under intense pressure deep within a larger body. The team calculated the conditions required to produce the mineral and found that it would have needed at least 17.5 kilobars of pressure to form.

The findings suggested that the parent body of the angrites must have had a radius of at least 1,000 kilometers (621 miles). Additional evidence suggested an even larger source. The crystals within NWA 12774 still retain sharp edges and delicate chemical features. If they had formed deep inside a massive world, those details would likely have been erased over time.

The researchers believe that the original world may have exceeded 1,800 kilometers (1118 miles) in radius, which is comparable to the size of Earth's moon and potentially approaching the scale of Mars.

Why It Matters

This discovery helps us understand how planets formed in the early days of our solar system. It also shows that there are still many mysteries waiting to be uncovered in the field of planetary science.

Key Facts

• A massive world existed 4.5 billion years ago and was shattered into pieces.
• The discovery came from a rare meteorite called Northwest Africa (NWA) 12774, an angrite meteorite.
• The parent body of the angrites must have had a radius of at least 1,000 kilometers (621 miles).
• The original world may have exceeded 1,800 kilometers (1118 miles) in radius, comparable to the size of Earth's moon and potentially approaching the scale of Mars.
• The discovery points to a type of planetary evolution unlike anything previously recognized.

Key Terms

Protoplanet

A large body that existed before planets formed in our solar system

Implications

This discovery helps us understand how planets formed in the early days of our solar system. It also shows that there are still many mysteries waiting to be uncovered in the field of planetary science.