A grapefruit-sized fireball from the mysterious Oort Cloud could rewrite the history of the solar system
A dazzling ball of fire 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 on camera on February 22, 2021, the rocky, grapefruit-sized meteoroid is believed to come 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 believed that it contains only icy objects. But the rocky object that burned up over Canada challenges popular theories about the formation of the Oort Cloud and the formation of the early solar system in general, according to a study published December 12 in the journal. nature astronomy (opens in a new tab).
“This discovery supports an entirely different model of solar system formation, which supports the idea that significant amounts of rocky material coexist with icy objects within the Oort cloud,” said the study’s lead author. Denis Lifepostdoctoral researcher in meteorite physics at Western University in London, Ontario, Canada, said in a statement. “This result is not explained by currently favored models of solar system formation. It is a complete game changer.”
According to NASA, the Oort Cloud is believed to have formed when the gravity of newly formed planets pushed icy objects away from the sun. severity of the Milky Way galaxy caused objects to settle on the edge of the solar system.
A current popular theory of how the solar system formed is the pebble buildup model, which describes millimeter-sized pebbles being sucked together over time to form celestial bodies.
“These findings challenge models of solar system formation based on pebble accretion alone, which currently cannot explain the large observed abundance of rocky material in the Oort cloud derived from fireball measurements and telescopic data. the authors wrote in the new study.
Rather, these results support what is known as the “Grand Tack” theory of solar system formation. This model proposes that Jupiter formed closer to the sun and migrated towards it before the gravitational effects between Jupiter and Saturn forced both planets further away. According to the researchers, only this model can explain enough of the rocky material from the inner solar system being ejected into the Oort cloud to explain the fireball.
The fireball was picked up by Global Fireball Observatory (GFO) from the University of Alberta. The GFO is a global collaboration between organizations including the Lunar and Planetary Institute, NASA Goddard Space Flight Center, and several universities. Your goal is to get images of fireballs so that the meteors can be recovered.
Calculations of the fireball’s trajectory show that it traveled from the far 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. Then it too broke apart, just like a normal rocky fireball does.
However, the Alberta fireball is not unique. The researchers found a similar fireball in a historical database that was never noticed at the time. These multiple rocky bodies suggest that between 1% and 20% of meteoroids from the Oort Cloud are rocky, the authors said.
“The better we understand the conditions in which the solar system formed, the better we will understand what it took to generate life,” Vida said. “We want to paint a picture, as accurately as possible, of these early moments in the solar system that were so critical to everything that happened after.”