A dazzling fireball that ended its cosmic journey over central Alberta, Canada, could change astronomers’ understanding of how the solar system formed 4.5 billion years ago.
Captured by camera on February 22, 2021, the rocky, grapefruit-sized meteoroid is thought to originate from the Oort Cloud, a reservoir of celestial objects that surrounds the entire Solar System and separates it from interstellar space. Scientists have never directly observed rocky objects in the Oort Cloud and have long thought it contains only icy objects. But the rocky object that burned up over Canada challenges conventional theories about how the Oort cloud formed and the formation of the early solar system more generally, according to a study published Dec. 12 in the Journal natural astronomy (opens in new tab).
“This discovery supports an entirely different model of solar system formation, one that supports the idea that significant amounts of rocky material coexist with icy objects in the Oort Cloud,” said the study’s lead author Denis Vidaa meteor physics postdoctoral fellow at Western University in London, Ontario, Canada, said in a expression. “This result cannot be explained by the currently preferred models for the formation of the solar system. It’s a complete game changer.”
According to NASAThe Oort Cloud is thought to have formed when the gravity of the newly formed planets pushed icy objects away from the Sun. gravity from the Milky Way galaxy caused the objects to settle at the edge of the solar system instead.
A popular current theory about how the solar system formed is that pebble accumulation Model describing millimeter-sized pebbles that over time are sucked together into celestial bodies.
“These results challenge solar system formation models based solely on pebble accretion, which currently cannot explain the large observed abundance of rocky material in the Oort Cloud inferred from fireball measurements and telescopic data,” the authors write in the new Study.
Rather, these results support the so-called “Grand Tack” theory of solar system formation. This model suggests that Jupiter formed closer to the Sun and migrated toward it before gravitational effects between Jupiter and Saturn forced both planets further outward. Only this model can explain that enough rock material from the inner solar system is ejected into the Oort cloud to explain the fireball, the researchers say.
The fireball was picked up by Global Fireball Observatory (GFO) cameras operated by the University of Alberta. The GFO is a global collaboration between organizations such as the Lunar and Planetary Institute, NASA Goddard Space Flight Center and several universities. His goal is to map fireballs so meteorites can be recovered.
Calculations of the fireball’s trajectory show it came from the outer reaches of the solar system, similar to the trajectories of icy comets – the objects thought to inhabit the Oort Cloud. The rocky nature of the fireball was confirmed by its descent deeper into Earth’s atmosphere than icy objects traveling in a similar orbit could survive. It then also broke apart, just like a normal rocky fireball.
The Alberta fireball is not an isolated incident, however. Researchers found a similar fireball in a historical database that was never noticed at the time. These numerous rock bodies suggest that between 1% and 20% of meteoroids emerging from the Oort Cloud are rocky, the authors said.
“The better we understand the conditions under which the solar system formed, the better we understand what was necessary to spark life,” Vida said. “We want to paint as accurate a picture as possible of those early moments in the solar system that were so crucial to everything that happened after.”