How specific asteroids and comets make repeat appearances after so many years of space is an endless and ever expanding vacuum.

Question

I feel like the answer can only be “ping pong” with another gravitational body, but that seems far too coincidental.

In: Planetary Science

Answer 1

Those asteroids and comets reappear because they’re orbiting the sun, just like Earth and everything else in the solar system. Their orbits are often eccentric (highly elliptical, and/or tilted with respect to the planets), but they’re still gravitationally bound to the sun. The effect of expansion is only seen in the distances between galaxies.