A rare meteorite found in the Sahara, Northwest Africa 12774, is making waves in the scientific community. This unassuming rock, weighing in at just under half a kilogram, holds the key to unlocking a lost world from the dawn of our solar system. The story of this meteorite is a captivating one, blending scientific discovery with the mysteries of our cosmic past.
A Rare Discovery
The meteorite, discovered in 2019, is a member of the angrites class, a group of ancient volcanic rocks that formed in the early days of our solar system. These rocks are like time capsules, preserving the conditions of the early solar nebula. What sets NWA 12774 apart is its unique chemistry and the clues it provides about a lost world.
Unraveling the Mystery
Scientists, led by Aaron Bell, made a groundbreaking discovery while studying the meteorite. They found that the clinopyroxene crystals within NWA 12774 were unusually rich in aluminium, indicating that the rock had formed under immense pressure. To understand this pressure, they developed a novel barometer, revealing that the rock crystallized at pressures equivalent to the deepest ocean trenches on Earth. This finding challenged the assumption that angrites originated from small asteroids.
Size Matters
The pressure measurements suggested a parent body with a radius of at least 1,000 kilometres, but further analysis revealed a more intriguing possibility. The crystals formed at relatively shallow depths, implying a larger body with a radius exceeding 1,800 kilometres. This size estimate places the lost world in the realm of small planets, comparable to the Moon. Bell's team's findings are astonishing, considering the size of the world that once existed.
A Different Chemistry
The chemistry of NWA 12774 is what truly sets it apart. It lacks the silica-rich composition typical of Earth and Mars, indicating a distinct developmental pathway. This suggests that the lost world formed from a unique mixture of the first solids to condense from the solar nebula, following a different course of development. It's a fascinating glimpse into the diversity of planetary formation.
A Violent End
The story of this world's demise is a tragic one. The favoured explanation is that it was destroyed in a violent collision during the early stages of planetary assembly. Some of its debris may have contributed to the formation of growing worlds, including Earth, while others became the angrites we find today. This inference highlights the fragility of these early worlds.
Unlocking the Past
The discovery of NWA 12774 opens up exciting possibilities for understanding our solar system's history. The next steps involve independent verification and applying the barometer to other angrites to confirm the giant parent body theory. Bell's team suggests that many meteorites remain largely unstudied, hinting at the potential for uncovering more lost protoplanets.
In conclusion, this meteorite is a window into a lost world, one that formed beside the young Sun, followed a unique chemical path, and met its end before Earth was fully formed. As scientists continue to explore these ancient rocks, we may uncover more secrets of our solar system's early days, challenging our understanding of planetary formation and evolution.
