A lump of meteorite found in the desert sands of Algeria could be a piece of a child’s planet that has never been made.
According to an in-depth study of the composition and age of the rock, not only is the meteorite known as Erg Chech 002 older than Earth, it formed volcanically – suggesting that it may once have been part of bark of something called a protoplanet.
As such, it represents a rare opportunity to study the early stages of planet formation, and to learn more about the conditions in the earliest days of the Solar System, when the planets we know and know today still creating.
EC 002 was discovered just last May, several pieces of rock with a combined weight of 32 kilograms (70 pounds) in the sandy sea of Erg Chech in southwestern Algeria. It was quickly identified as unusual; rather than the chondritic shape of most recovered meteorites – which form when pieces of dust and rock adhere to each other – its texture was igneous, with the inclusion of pyroxene crystals .
It was thus classified as achondrite, a meteorite made of volcanic material, which came from a body that went through internal melting to differentiate the heart from the crust – protoplanet, one of the middle stages of planetary formation.
Of the tens of thousands of meteorites identified, only a few thousand – 3,179, according to the Meteoritical Journal Database – are achondrites.
Most of these achondrites come from one of two parent groups, and are basaltic in writing. This means that they cannot tell us much about the diversity of protoplanets in the early Solar System.
EC 002, on the other hand, is not basaltic, but a type of volcanic rock called andesite, a team of scientists led by geologist Jean-Alix Barrat from the University of West Britain in France, has been proven.
Of all the meteorites we’ve found so far, even among achondrites, that makes EC 002 very rare – and opens up a new avenue for understanding planetary formation.
According to the team’s survey, the rock ancient. The radioactive decay of aluminum and magnesium isotopes suggests that these two minerals crystallized around 4.565 billion years ago, in a parent group that amassed 4.566 billion years ago. For context, the Earth is 4.54 billion years old.
“This meteorite is the oldest magmatic rock studied to date and sheds light on the formation of the primordial crusts that covered the oldest protoplanets,” the researchers wrote in their paper .
Unlike basalt, which comes from the rapid cooling of lava rich in magnesium and iron, andesite is composed mostly of sodium-rich silicates, and – on Earth, at least – forms. in movement zones, where the edge of a single tectonic plate is pushed down. other.
Although rarely found in meteorites, the recent discovery of andesite in meteorites found in Antarctica and Mauritania has inspired scientists to study how it could have occurred. Experimental evidence suggests that it can form from the melting of chondritic material.
Given the prevalence of chondritic groups in the Solar System, it is possible that the formation of protoplanets with andesite crusts was also common. However, when the team compared the spectral features of EC 002 – that is, the way it interacts with light – with the celestial properties of asteroids, they could find nothing in the Solar System. which matched the meteorite.
Remains of the Andesitic crust are rare in the meteorite plate; they are also rare in the asteroid belt. Which begs the question: if the creation process was so simple and common, then where the heck did the different protoplanets come from?
In the same place most of the material in the Solar System came to an end, perhaps: either they were crushed, or incorporated into larger rocky bodies; or, perhaps, a combination of both.
Since EC 002 is slightly older than Earth, it is even possible that its protoplanetary sisters went on to help lift the Earth from a knot of denser material in the dust cloud left by the baby Sun.
While we have a very reasonable grasp of how baby planets are born, growing over millions of years as lumps of rocks and dust stick together, the details of the process are a bit more mysterious. .
EC 002 represents a remarkable opportunity to improve our understanding of how our home system came out of the dust.
The research was published in PNAS.