A rocky meteoroid that exploded over Canada last year was more extraordinary than it first seemed: it originated from the outer Solar System, where scientists thought only icy bodies exist. A cavalcade of astronomers caught images and videos of the meteoroid as it exploded over Alberta. By studying this data, researchers have determined that the meteoroid broke apart like a rocky object, surviving deeper into Earth’s atmosphere than icy objects on similar trajectories. The analysis also suggested that the meteoroid came from the Oort Cloud, far beyond Pluto. Discovering a rocky body from this region could rewrite existing theories of how the Solar System formed. “This discovery supports an entirely different model of the formation of the Solar System, one which backs the idea that significant amounts of rocky material coexist with icy objects within the Oort Cloud,” Denis Vida, a meteor physics specialist at Western University in Canada, said. “This result is not explained by the currently favoured Solar System formation models. It’s a complete game changer.”
Scientists have always believed that the Oort Cloud consists exclusively of icy objects. When passing stars displace these Oort Cloud objects, they head into the inner Solar System as comets. As they do, radiation from the Sun causes ice to change from solid to gas, blowing off material that forms the cometary tails of gas and dust that can stretch millions of miles. While astronomers haven’t directly seen an object in the Oort Cloud, they have seen many cometary objects that started life in the region, and they’ve all been made of ice.