Did scientists in Sweden uncover the first ever “extinct” alien rock?
The object, now named Oest 65, was discovered in Sweden’s Thorsberg quarry, close to the village of Österplana, back in 2011, but it took researchers five years to figure out what it is. It measures 8 centimeters (3 inches) long, and is thought to be around 470 million years old.
The Österplana meteorite, embedded in limestone from the Ordovician period. Photo credit: Birger Schmitz
"The single meteorite that we found on the Ordovician seafloor is of a type that we do not know of from today's world," study first author Birger Schmitz from Lund University told Charles Q. Choi at Space.com. "This hints that the types of meteorites that fell on Earth in the ancient past were very different than those falling today."
If confirmed an extinct meteorite — meaning it’s a class of rock that no longer plunges into the Earth — it could tell us more about the collisions that go on in outer space, as well as provide a larger picture of the materials involved in the birth of our solar system 4.6 billion years ago.
"This is the first documented example of an extinct meteorite," explained Schmitz. "We knew of extinct animals, and it has been speculated that there is something like extinct meteorites, but this is the first one found."
What makes the meteorite so unique is that it features grains of crystals, known as spinels, which aren’t the same as the ones found in all other known meteorites. Also, its ratio of chromium to oxygen isotopes is unlike any known meteorite types.
"For a long time we called the meteorite 'the mysterious object' because we could not understand what it was," Schmitz said.
According to the press release, just like the 100 L-type chondrites discovered to date — the most common type of ordinary chondrite that falls into the planet — the new meteorite had sunk to the bottom of the ocean floor. The researchers hypothesize that the meteorite is a fragment of an asteroid that measures 100-150 kilometer (62-93 miles) across, that slammed into a parent asteroid responsible for all the L-type chondrites found on Earth.
If the researchers can determine where this “mysterious object” came from, it could give clues about how life on Earth was evolving 470 million years ago.
"If we see that changes in the asteroid belt correlate with changes in Earth's biosphere or climate, then there is probably a connection and we will be able to better tie Earth's history to the history of the solar system," said Schmitz.
In fact, during the Ordovician Period when the meteorite landed on Earth, the planet was experiencing a massive expansion in the diversity of marine animals, and the first formation of the coral reefs. According to the researchers, it might be possible to link these shifts to the impact event.
The study has been published in the journal Nature Communications.
You might also like: The Fate of the World May Rest in the Hands of Two Walnut-Sized Meteorites