Sixty-five million years ago, a 10-km-wide asteroid slammed into Earth, killing off the dinosaurs. While that’s the best-known Earth-asteroid collision, the truth is, space debris rains down on us all the time, notes Yeomans, manager of NASA’s Near-Earth Object Program Office. He and other scientists are on a mission to track the largest asteroids that swarm around our planet, and his book is a behind-the-scenes look at how they do it—hopefully finding them before they find us.
The first asteroid, named Ceres, was discovered in 1801, but it wasn’t until the 1990s that astronomers understood just how many there were. Our planet passes through a veritable “shooting gallery” of millions of comets and asteroids on its tour around the sun, Yeomans writes. Long viewed as “the vermin of the skies,” we now understand how useful they can be. Asteroids and comets, “the leftover bits and pieces” of our solar system, can tell us a lot about how the planets formed. Asteroids can also be rich in valuable resources like platinum, which explains why mining companies are eyeing them as future destinations; maybe soon, we could send astronauts to visit one. (In 2010, President Obama said he’d like to have astronauts reach a near-Earth asteroid by 2025.)
Yeomans credits near-Earth objects with the origins of life. “The Earth formed hot without significant supplies of water and organic materials,” he writes, but after a pummelling from space, “received a veneer of water and organic carbon-based materials that allowed life to form.” If they gave life to our planet, they could also take it away. Yeomans’ book is a fascinating account of science that could literally save the world.
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