How do planets clear out objects on the other side of their orbit?

To be a planet, NASA says an object must be big enough that its gravity has cleared away any other objects of a similar size near its orbit around the Sun. I can understand how something can clear objects close to itself, but how does it clear something 180° away in its orbit? Rebecca SmithWashougal,Continue reading "How do planets clear out objects on the other side of their orbit?" The post How do planets clear