planetàry

Planetary is a term that can refer to several different concepts, depending on the context. In astronomy, "planetary" directly relates to planets, celestial bodies that orbit a star, are massive enough to be rounded by their own gravity, and have cleared the neighborhood around their orbit. This includes the eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, as well as numerous exoplanets discovered around other stars. The study of planets, their formation, evolution, and characteristics is known as planetary science.

Beyond its astronomical meaning, "planetary" can also be used metaphorically to describe something of vast scale or scope, encompassing an entire planet. For example, one might speak of a "planetary impact" or a "planetary phenomenon" to indicate its global reach. In some contexts, particularly in older or less formal usage, it might also refer to things associated with the earth or the physical world, distinct from the celestial or spiritual. The word's root comes from the Greek "planētēs," meaning "wanderer," a term ancient astronomers used for celestial bodies that moved across the sky independently of the fixed stars.