A meteor burned down in the sky over the Canadian province of Alberta nearly two years ago. In and of itself, this is not unusual; our planet is under constant bombardment by chunks of rocks that fall into its atmosphere from space. Some of those are quite large and end up burning spectacularly as fireballs.
These fireballs or "shooting stars" are meteors, observed when meteoroids enter Earth's atmosphere at high speed and burn up. But the meteor that exploded over Canada was unusual enough, scientists later learned. Based on its trajectory, it came from Oort Cloud, a vast sphere of icy objects at the edge of our Solar System. The way it exploded indicated to scientists that its composition was completely different to ice.
"This was the first direct observation of a larger rocky, or not icy body coming from the Oort Cloud," says Slovak astronomer Pavol Matlovič from Comenius University in Bratislava. Along with his colleague Juraj Tóth he contributed to the study of the meteor, recently published in Nature Astronomy, by providing data from their meteor orbit network system.