Michael Byers holds the Canada Research Chair in Global Politics and International Law. Aaron Boley holds the Canada Research Chair in Planetary Astronomy. Both are at the University of British Columbia, where they co-direct the Outer Space Institute.
On Wednesday evening, depending on where in Canada you are, you might be leaving school or work, having dinner, or already fast asleep in bed.
Meanwhile, an asteroid the size of a seven-storey building – designated 2019 EA2, to reflect the fact that it is the second asteroid to pass close to Earth this year, and spotted just two weeks ago through a telescope in Arizona – will buzz by the planet we call home. The good news? The 24-metre-wide asteroid will miss us by 300,000 kilometres.
The bad news: asteroids do hit the Earth. Most harmlessly break into pieces as they enter Earth’s atmosphere, but even a relatively small asteroid can damage property and injure people. In 2013, a 17-meter-wide asteroid sent 1,500 people to hospital in Chelyabinsk, Russia, most of them injured by flying glass from broken windows.
The energy released by an asteroid of that size can be equivalent to 500 kilotons of TNT, about 25 times more than the nuclear bomb dropped on Hiroshima. These events seem to occur on average every 50 years, at high altitudes.
Smaller asteroids strike the Earth more frequently, but are less energetic. Just this week, the U.S. military reported that another small asteroid caused a 170-kiloton airburst last December over the Bering Sea, west of Alaska.