A mysterious meteorite found in Sweden appears to be the first of its kind found anywhere in the world. Astronomers are referring to the object as an "extinct meteorite." Analysis also reveals it may be the final product of an ancient collision between two rocky bodies, which took place 470 million years in the past.
Meteorite Ost 65 was discovered sitting in a quarry, and the body may have played a significant role in the geological history of the Earth. The collision which shaped this object may have sent a significant amount of debris to Earth over the course of roughly 1 million years. As meteors fell to the Earth at a rate 100 times greater than today, the encounters may have played a significant role in the growth in the diversity of life seen during the Ordovician Period. Today, L-chondrites, which fell to the Earth during this time, are still the most common variety of all meteorites.
"In our entire civilization, we have collected over 50,000 meteorites, and no one has seen anything like this one before. Discovering a new type of meteorite is very, very exciting," Qing-zhu Yin, professor of geochemistry and planetary sciences at the University of California, Davis said.
Ost 65 is an example of a fossil meteorite, which derive their name from their great age. Over hundreds of millions of years, most of the rock becomes chemically altered, while a handful of components, including chromite and spinels, remain intact. The body is also considered to be an extinct meteorite, since it is of a variety that no longer falls to Earth.
By studying how long the object was exposed to cosmic rays, astronomers determined it traveled through space for roughly a million years before falling to Earth 470 million years ago. Examination of isotopes within the meteorite reveals the object differs from all other meteorites seen on Earth, including the many L-chondrites found in the quarry. This suggests Ost 65 may be a piece of the other body from the collision which did not fall to the ground. Where the rest of that object resides, or even if it still exists, remains a mystery to this day.
This new finding suggests samples of meteorites which have arrived on Earth in the geologically-recent past do not represent the full diversity of object cruising through the solar system. Meteorite relics from the distant past may still be trapped within archaic rocks found deep under the surface of our planet.
Discovery and analysis of Ost 65 was profiled in the journal Nature Communications.