Asteroid Defense: Detection is Key

An asteroid just flew past Earth… inside the Moon’s orbit. So—how close is...

too close… and if one was headed for us… could we actually stop it? “First: ‘close’

doesn’t automatically mean ‘danger.’ Space is huge. What matters is two things: size

and odds. A pebble can hit us and burn up. A city-sized rock? Different story.”

We love saying ‘it passed near Earth’—but the real question is: could it hit later?

Astronomers flag objects that come near Earth’s orbit and are big enough to matter.

The scary part isn’t the one that misses by a few hundred thousand kilometers—it’s the one that threads

a tiny invisible lane called a gravitational keyhole. “Miss the keyhole today… and you’re