How 4.5 billion-year-old space rocks reveal the Earth's hidden interior
A single meteorite fragment can act as a cosmic time capsule. By studying the chemical composition of ancient stones like the Allende and Imilac meteorites, scientists can reconstruct the violent, molten beginnings of our solar system and peer into the unreachable depths of our own planet.
The history of our solar system is written in the chemistry of meteorites. The Allende meteorite, which fell to Earth in 1969, contains tiny grains known as chondrules. These once-molten droplets serve as a record of the pressure and temperature present during the solar system's infancy. By applying the principles of chemical thermodynamics, researchers like Denton Ebel of the American Museum of Natural History can decode these leftovers to understand how planets form, even in distant solar systems.
Pallasite meteorites, such as the Imilac specimen, offer a structural blueprint for planetary formation. These stones are composed of a striking mix of iron, nickel, and green-yellow olivine crystals. Traditionally, scientists believed pallasites formed at the boundary where a planetesimal's heavy iron-nickel core meets its lighter rocky mantle. However, recent studies suggest that high-energy, 'hit-and-run' collisions in the crowded early solar system may have disrupted these bodies, mixing core and mantle materials together.
Because we cannot drill deep enough to sample Earth's center, these meteorites serve as vital analogues. The process that created the layered structure of a planetesimal—heavy metals sinking to the center while lighter rocks rise to form a mantle—is the same process that shaped Earth. By studying the composition of p-type meteorites, geologists and seismologists can better understand the structure of our own iron-nickel core and rocky mantle.
The Imilac meteorite itself is a fragment of a much larger body, possibly a 1,000-kilogram meteor that exploded over Chile's Atacama Desert, potentially as far back as the fourteenth century. While many meteorites degrade when exposed to Earth's atmosphere, the Imilac is exceptionally stable, making it a permanent resource for both public display and ongoing scientific research.
Source: This Space Rock is 4.5 Billion Years Old. Here's Its Secret...
