Comet Lulin is arriving from the far reaches of the solar system on a nearly parabolic orbit—”it’s almost as if it comes from infinity and goes back out to infinity,” he said.

This must have been one of these initially stationary objects then. Speaking of orbits, unrelated to comets, these so-called halo orbits are pretty amazing. They are orbits around stationary points in the gravitational field of three bodies called Lagrange points. L1, L2, and L3 are pretty obvious and therefore not that cool, but L4 and L5 surprised me and they are even stable… The application of going to an unstable Lagrange point and redirecting routing with low energy is even nicer.