Astronomy Can Save Your Life: The Search for Near-Earth Objects

There's a lot of stuff floating around in the Solar System, and occasionally some of it crashes into Earth. People worry about the dinosaur-killer events, but those happen only every 100,000,000 years or so. Much more common --- once a decade? --- are the city-killer-size events like the near-miss Chelyabinsk meteor. These 20-meter sized asteroids can now be detected and tracked, sometimes with astonishing accuracy due to recent breakthroughs in astrometry, but sometimes they're lost and must be found again. The same instrumentation network that makes these finds also detected the weird interstellar "asteroid" Oumuamua.