What is a small body that follow a highly elliptical orbit around the sun

Planets

Examples:
1. Mercury
2. Venus
3. Earth

Motions in this direction are referred to as direct motions while motions in the opposite direction are referred to as retrograde. Retrograde motion is the apparent backward motion of a planet caused by its being lapped by another planet or vice versa. Both planet move in a direct eastward motion around the sun, but the planet with the inside (smaller) orbit moves faster than the planet on the outside (larger orbit), and when it passes the slower moving planet, each sees the other one as apparently moving backward relative to its motion around the sky.

Answer) by studying proton collisions hope this : )