'Unexpected' Fireball From Edge Of Solar System Challenges Theories About The Latter's Origin: Study
The fireball was a grapefruit-sized rocky meteoroid, weighing approximately two kilograms. It broke apart in Earth's atmosphere exactly like a fireball dropping stony meteorites.
An 'unexpected' fireball from the edge of the solar system has challenged some age-old theories about the latter's origin. The fireball was likely made of rock, not ice, researchers from University of Western Ontario have shown. The study describing the findings was published recently in the journal Nature Astronomy.
What is the Oort Cloud?
A collection of icy objects called the Oort Cloud floats through space just at the edge of the solar system. The Oort Cloud is located halfway to the solar system's nearest stars. Sometimes, when passing stars nudge the icy objects towards the Sun, people on Earth see them as comets with long tails. Though scientists have not yet observed objects in the Oort Cloud directly, everything detected so far coming from the collection's direction has been made of ice.
Theories about the solar system's origin are based on the understanding that only icy objects exist in the outer reaches of the system, and nothing made of rock is present there.
The Alberta fireball originated from the middle of the Oort Cloud
However this belief changed last year when an international team of scientists, stargazers, and professional and amateur astronomers led by meteor physicists at University of Western Ontario captured images and videos of a rocky meteoroid that flew through the skies over central Alberta as a dazzling fireball. According to the researchers, all signs point to the fireball's origin being precisely in the middle of the Oort Cloud.
In a statement released by University of Western Ontario, Denis Vida, one of the authors on the paper, said the discovery supports an entirely different model of the formation of the solar system. The model backs the idea that significant amounts of rocky material co-exist with icy objects within the Oort Cloud. The result is a game-changer and cannot be explained by the currently favoured models on the formation of the solar system.
What did the fireball look like?
Since all previous rocky fireballs have arrived much closer to Earth, the fireball detected over Alberta, which travelled vast distances, was completely unexpected.
The fireball was a grapefruit-sized rocky meteoroid, weighing approximately two kilograms, state-of-the-art Global Fireball Observatory (GFO) cameras, developed in Australia and run by the University of Alberta, revealed.
The researchers calculated that the fireball was travelling on an orbit usually reserved only for icy long-period comets from the Oort Cloud.
How the researchers knew the fireball was made of rock
The Alberta fireball, during its flight, descended much deeper into the atmosphere than icy objects on similar orbits. It broke apart exactly like a fireball dropping stony meteorites. This was the necessary evidence of the fact that the object was made of rock.
Meanwhile, comets are fluffy snowballs mixed with dust that slowly vaporise as they approach the Sun. The dust and gases within comets form the distinctive tail that can stretch for millions of kilometres, according to the university.
Significance of the study
Vida said the researchers want to understand how the rocky meteoroid ended up so far away, because they want to understand the origins of life on Earth. The better the researchers understand the conditions in which the solar system was formed, the better they will understand what was necessary to spark life.
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