Rocky meteoroid that exploded over Canada came from the edge of the solar system

This is an extraordinary finding because scientists thought only icy bodies existed there.

Published : Dec 29, 2022 10:30 IST

The fireball captured by the Global Fireball Observatory camera over  Alberta.

The fireball captured by the Global Fireball Observatory camera over Alberta. | Photo Credit: University of Alberta, Canada

IN 2021, an international team of professional and amateur astronomers, led by planet scientists of Western University in Ontario, Canada, captured images and videos of a meteoroid that exploded over central Alberta as a dazzling fireball. The scientists have now determined that it originated from the edge of the solar system and was rocky in composition. This is an extraordinary finding because scientists thought only icy bodies existed beyond the solar system.

From the fireball data, researchers determined that the meteoroid broke apart like a rocky object, with pieces surviving deeper in the earth’s atmosphere than icy objects would do. The analysis also suggested that it lay in the middle of the Oort Cloud, the giant shell of billion to trillion icy bodies that is believed to encircle the solar system far beyond Pluto. Passing stars sometimes nudge these icy bodies towards the sun, and these are comets with long tails. Comets are basically fluffy snowballs mixed with dust that slowly vaporise as they approach the sun. The dust and gases form the distinctive tail that can stretch for millions of kilometres.

No object in the Oort Cloud has been observed directly, but everything coming from that direction has been found to be made of ice. According to the present theoretical understanding of the solar system’s beginnings, only icy objects exist in these outer reaches, so discovering a rocky body from this region does not gel with the existing theories solar system formation. The puzzling findings were published in Nature Astronomy.

“This discovery supports an entirely different model of the formation of the Solar System… that significant amounts of rocky material coexist with icy objects within the Oort cloud,” said Denis Vida, a Western meteor physicist. “This result is not explained by the currently favoured Solar System formation models. It’s a complete game changer.” All previous rocky fireballs arrived from much closer to the earth. Cameras of the state-of-the-art Global Fireball Observatory (GFO), developed in Australia and run by the University of Alberta, observed the grapefruit-sized (approximately 2 kg) rocky meteoroid. Using Global Meteor Network tools, the Western researchers calculated that it was travelling on an orbit usually associated with icy long-period comets from the Oort Cloud.

“In 70 years of regular fireball observations, this is one of the most peculiar ever recorded. It validates the strategy of the GFO established five years ago, which widened the ‘fishing net’ to 5 million km2 of skies and brought together scientific experts from around the globe,” said Hadrien Devillepoix of Curtin University, Australia, and the principal investigator of the GFO.

“We want to explain how this rocky meteoroid ended up so far away because we want to understand our own origins. The better we understand the conditions in which the Solar System was formed, the better we understand what was necessary to spark life,” said Vida.

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