how were they described during antiquity?
Ancient Greek astronomers employed the term "asteres planetai" meaning "wandering stars", to describe those starlike lights in the heavens that moved over the course of the year
Definition of planet
Greek astronomers employed the term "asteres planetai" (ἀστέρες πλανῆται), "wandering stars", to describe those starlike lights in the heavens that moved over the course of the year,
what is the definition of a planet? A planet is a body that orbits the Sun, is massive enough for its own gravity to make it round and has "cleared its neighbourhood" of smaller objects approaching its orbit
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Definition of planet [SEP] Planets in antiquity
While knowledge of the planets predates history and is common to most civilizations, the word "planet" dates back to ancient Greece. Most Greeks believed the Earth to be stationary and at the center of the universe in accordance with the geocentric model and that the objects in the sky, and indeed the sky itself, revolved around it (an exception was Aristarchus of Samos, who put forward an early version of heliocentrism). Greek astronomers employed the term "asteres planetai" (ἀστέρες πλανῆται), "wandering stars", to describe those starlike lights in the heavens that moved over the course of the year, in contrast to the "asteres aplaneis" (ἀστέρες ἀπλανεῖς), the "fixed stars", which stayed motionless relative to one another.