Explained: Near-miss asteroids
On May 29, an asteroid the size of a bus came whizzing past Earth at 10 times the speed of a fired bullet. The near-miss asteroid, named 2012 KT42 — or “KT42” for short — streaked across the orbits of weather and television satellites, 22,000 miles above Earth’s surface, making it the sixth-closest asteroid approach on record. While the object had little chance of colliding with Earth, its approach gave scientists an opportunity to run a rapid-response program — or as MIT’s Richard Binzel calls it, an asteroid-tracking “fire drill” — to gain as much information as possible from the incoming space rock. “This thing missed, but chances are, at this size, we will one day find an object headed for an impact,” says Binzel, a professor of planetary sciences in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “Depending on where it’s falling, you might need to know whether...