In classical antiquity, the seven classical planets are the seven non-fixed astronomical objects in the sky visible to the naked eye: Mars, Jupiter, Venus, Saturn, Mercury, the Sun, and the Moon.
The word planet comes from two related Greek words, πλάνης planēs (whence πλάνητες ἀστέρες planētes asteres "wandering stars, planets") and πλανήτης planētēs, both with the original meaning of "wanderer", expressing the fact that these objects move across the celestial sphere relative to the fixed stars.
Often divided the seven planets into the Sun, the Moon, and the five planets.
The term planet in modern terminology is only applied to natural satellites directly orbiting the Sun, so that of the seven classical planets, five are planets in the modern sense.
Shows Greek personifications of planetary gods charged with early versions of the planetary symbols: Mercury has a caduceus; Venus has, attached to her necklace, a cord connected to another necklace; Mars, a spear; Jupiter, a staff; Saturn, a scythe; the Sun, a circlet with rays radiating from it; and the Moon, a headdress with a crescent attached.
A diagram in Johannes Kamateros' 12th century Compendium of Astrology shows the Sun represented by the circle with a ray, Jupiter by the letter zeta (the initial of Zeus, Jupiter's counterpart in Greek mythology), Mars by a shield crossed by a spear, and the remaining classical planets by symbols resembling the modern ones, without the cross-mark seen in modern versions of the symbols.
The Ptolemaic system used in Greek astronomy placed the planets in order, closest to Earth to furthest, as the Moon, Mercury, Venus, Sun, Mars, Jupiter, and Saturn.
In addition the day was divided into 7 hour intervals, each ruled by one of the planets, although the order was staggered (see below).
The first hour of each day was named after the ruling planet, giving rise to the names and order of the Roman seven-day week. It can be correlated that the Norse gods were attributed to each Roman planet and its god, probably due to Roman influence rather than coincidentally by the naming of the planets.
Modern Latin-based cultures, in general, directly inherited the days of the week from the Romans and they were named after the classical planets; for example, in Spanish Miércoles is Mercury, and in French Mardi is Mars-day. In alchemy, each classical planet (Moon, Mercury, Venus, Sun, Mars, Jupiter, and Saturn) was associated with one of the seven metals known to the classical world (silver, mercury/quicksilver, copper, gold, iron, tin and lead respectively).
The modern English days of the week were inherited from gods of the old Germanic Norse culture — Wednesday is Wōden’s-day (Wōden or Wettin eqv. As a result, the alchemical glyphs for the metal and associated planet coincide.
Alchemists believed the other elemental metals were variants of these seven (e.g.