Just after midnight on January 21, a roughly three-foot-long asteroid fell through Earth’s atmosphere—burning up in a blazing fireball seen across much of Europe and crashing to the ground as fragments of meteorite near Berlin, Germany.
When scientists arrived on the scene to recover and classify the pieces, they discovered something remarkably rare: The rocks belonged to an extremely uncommon group of meteorites known as aubrites, which remain mysterious to researchers. Just 80 of the roughly 70,000 recovered meteorite fragments had been classified as aubrites prior to this new impact.
“Currently, there isn't an agreed-upon origin of aubrites, and several candidates have been put forward: the Nysa asteroid family, asteroid 3103 Eger and even the planet Mercury,” Denis Vida, a meteor physics researcher at Western University in Canada, tells Robert Lea of Space.com. “They make up only 1 percent of all known meteorites, making it very rare indeed.”
Here's the full video of the asteroid #Sar2736, a ~1 m object that broke up some 50 m west of #Belin, #Germany, and probably dropped some meteorites on the ground. Video credit: https://t.co/72o6ZzPNz8 pic.twitter.com/PA73dkqid1— Denis Vida (@meteordoc) January 21, 2024
Hungarian astronomer Krisztián Sárneczky first spotted the asteroid, named 2024 BX1, about three hours before impact, and NASA tracked its trajectory to predict where it would fall—in itself a rare feat. The object did not harm any people.
As news of the impact spread to the public, meteorite hunters began scouring Ribbeck, a village near Berlin, for fragments of the rock. But the search proved particularly challenging. Unlike most meteorites, which have a thin crust of black glass, aubrites do not appear glossy or dark in color.
“Aubrites look more like a gray granite,” Christopher Hamann from Berlin’s Natural History Museum says in the statement. “It looks completely different than most other meteorites. Aubrites are therefore difficult to detect in the field.”
Peter Jenniskens, an astronomer at the SETI Institute, flew to Germany from California hours after he heard about the 2024 BX1 impact, reports Jonathan O’Callaghan of the New York Times. Though he had participated in three other meteorite searches in the past, it took several days for Jenniskens and a team of students and volunteers to come across these fragments about the size of a walnut.
“They were devilishly difficult to find, because from a distance, they look like other rocks on Earth. Close up, not so much,” Jenniskens says in the statement. “We only spotted the meteorites after a Polish team of meteorite hunters had identified the first find and could show us what to look for.”
The advice proved valuable—two hours after receiving the pointers, Jenniskens’ team found their first fragment. By the time they stopped looking, their search had revealed more than 20 meteorite pieces.
The official classification as an aubrite, following a mineralogy assessment conducted with an electron beam microprobe, came from Berlin’s Natural History Museum. Then, the International Nomenclature Commission of the Meteoritical Society confirmed it, reports Kelly Kizer Whitt for EarthSky. The museum collection contains a fragment from the first known aubrite meteorite that fell in 1836 near the village of Aubrés in France, which became the type’s namesake.
“Based on this evidence, we were able to make a rough classification relatively quickly,” Ansgar Greshake, scientific head of the museum's meteorite collection, says in the statement. “This underlines the immense importance of collections for research. So far, there is only material from 11 other observed falls of this type in meteorite collections worldwide.”
While Mercury remains a potential origin of aubrite meteorites, some astronomers find it unlikely in this case. The initial calculated orbit of 2024 BX1 appears wider, suggesting it came from outside of Earth’s orbit, per the Times.
“Therefore, this object could not have come to us directly from Mercury,” Marc Fries, a planetary scientist at NASA’s Johnson Space Center, tells the publication.
In a way, though, it might have come indirectly from Mercury, since the inner planet may have projected aubrites to the asteroid belt between Mars and Jupiter long ago. One of these might have just made its way to Earth, and that could account for the wide orbit. But Fries remains doubtful, per the Times.
Despite the uncertainty regarding the meteorite’s origin, its fragments hold information that can help scientists better understand the universe.
“With this being a fresh fall, enabling quick lab analysis and such an accurate orbit, I am confident that this rock will get us one step closer to understanding the origin of aubrites and help piece together the story of the formation of the solar system,” Vida says to Space.com.