> we can't predict where these objects will go Only on time scales like thousands of years or more, that are too long to worry about as far as any danger to Ea

> we can't predict where these objects will go Only on time scales like thousands of years or more, that are too long to worry about as far as any danger to Earth is concerned. On shorter time scales we can predict orbits very accurately, which is how astronomers know about objects that will pass near Earth decades in advance.