How near does an asteroid have to be before we need to be concerned with a planetary collision?
By your reckoning, artificial satellites should be pulled into Earth. The reason they don’t is velocity. The near-earth asteroids are travelling in Solar orbits and their velocity precludes them being captured unless they are on a more or less direct collision course. And .02 AU is not that close – its still couple million kms. I have been watching these things for some time and have seen approaches well inside Lunar orbit on many occasions (down to 36,000 kms on one occasion), and some time ago a small bolide skimmed our atmosphere and went off out into space again. No, it will take a near direct approach for impact to happen.
