Your terminology is flat-out wrong, sorry. Asteroids and comets are not differentiated by their orbital shape. But that's not what I'm disputing. Asteroids rou

Your terminology is flat-out wrong, sorry. Asteroids and comets are not differentiated by their orbital shape. But that's not what I'm disputing. Asteroids routinely have their orbits mucked with by the planets and get thrown into (1) elliptical orbits, (2) non-planar orbits, and (3) ejected. In the first two cases, we aren't even looking for them because there is so much space that it's not worth trying. Additionally, it is not true that we have found all dangerous NEO asteroids that are in ordinary orbits. NASA is still running a program whose goal is to find 90% of these [1]. For example, in just the past week they discovered a near-Earth object in excess of 1 km [2]. [1] http://neo.jpl.nasa.gov/faq/ http://neo.jpl.nasa.gov/faq/ [2] http://neo.jpl.nasa.gov/stats/ http://neo.jpl.nasa.gov/stats/