tertiary planet

名词noun

1. 1Used other than figuratively or idiomatically: see tertiary,‎ planet. (the third planet; usually counting outwards from the central sun)
2. 2(archaic, astronomy) A planet of the third-degree/third-order. The planet of a planet (secondary planet) of a planet (primary planet). An object (moonmoon) which orbits an object (moon) which orbits an object (planet) which orbits a star