A rocky meteoroid that exploded over Canada last year was more extraordinary than it first appeared: it came from the outer solar system, where scientists thought only icy bodies existed.
A cavalcade of professional and amateur astronomers took pictures and videos of the meteoroid as it exploded over Alberta. Studying this data, the researchers determined that the meteoroid broke up like a rocky object, surviving deeper in earth’s atmosphere than icy objects on similar trajectories. However, the analysis also suggested that the meteoroid originated from the Oort cloudwell beyond Pluto. The discovery of a rocky body from this region could rewrite existing theories about how the solar system shape.
“This discovery supports an entirely different model of the formation of the solar system, which supports the idea that significant amounts of rocky material coexist with icy objects in the Oort cloud,” said Denis Vida, a specialist in solar system physics. meteors at Western University of Canada, said in a statement. “This result is not explained by the currently favored models of solar system formation. This is a complete game-changer.”
A cool, rocky meteoroid
Scientists have always believed that the Oort cloud consists exclusively of icy objects. When passing stars displace these objects from the Oort cloud, they head towards the inner solar system as comets. As it does, radiation from the sun turns the ice from solid to gas, blowing off gas and dust that form the stereotypical cometary tails of gas and dust that can stretch for millions of miles or kilometers.
Although astronomers did not directly see an object in the Oort cloud, they did see many cometary objects that started life in the region, and they were all made of ice. This is how scientists came up with the idea that the outer solar system was made up of nothing but icy bodies and nothing rocky – a premise they used to develop theories about how our planetary system formed.
Rock fireballs are fairly commonly seen, but all of the previous examples are from much closer to Earthmaking this traveler, who has traveled long distances, completely unexpected.
The University of Alberta captured the rocky, 4.4-pound (2-kilogram) grapefruit-sized meteoroid using Global Fireball Observatory (GFO) cameras developed in Australia. Western researchers then calculated its orbit with the tools of the Global Meteor Network. This revealed that the meteoroid was traveling in an orbit usually occupied only by icy long-period comets from the Oort cloud.
“In 70 years of regular fireball sightings, this is one of the strangest on record,” Hadrien Devillepoix, planetary astronomer at Curtin University in Australia and GFO principal investigator, said in the statement.
“It validates the GFO strategy established five years ago, which expanded the ‘fishing net’ to 5 million square kilometers of sky and brought together scientific experts from around the world,” Devillepoix said. “This not only allows us to find and study valuable meteorites, but it’s the only way to have a chance of catching those rarer events that are critical to understanding our solar system.”
The team now wants to explain how this rocky meteoroid ended up so far from the inner solar system, hoping that this information will help to better understand the formation of planets in the solar system and Earth.
“The better we understand the conditions under which the solar system formed, the better we understand what was needed to trigger life,” Vida said. “We want to paint as accurate a picture as possible of those early moments in the solar system that were so critical to everything that happened after.”