Wandering stars

In classical antiquity, the sacred Seven Luminaries or what we now call the Seven Classical Planets are the seven non-fixed objects visible in the sky: the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn. The word planet comes from the Greek word πλανήτης, planētēs "wanderer" (short for asteres planetai "wandering stars"), expressing the fact that these objects move across the celestial sphere relative to the fixed stars.

The term planet in modern terminology is only applied to satellites orbiting the Sun, so that of the classical seven planets, five are planets in the modern sense, the five planets easily visible to the unaided eye.

Babylonians recognized seven planets. A bilingual list in the British Museum records the seven Babylonian planets in this order:

The astrological symbols for the classical planets, zodiac signs, aspects, lots, and the lunar nodes appear in the medieval Byzantine codices in which many ancient horoscopes were preserved. In the original papyri of these Greek horoscopes, there are found a circle with one ray () for the Sun and a crescent for the Moon. The written symbols for Mercury, Venus, Jupiter, and Saturn have been traced to forms found in late Greek papyri. The symbols for Jupiter and Saturn are identified as monograms of the initial letters of the corresponding Greek names, and the symbol for Mercury is a stylized caduceus. A. S. D. Maunder finds antecedents of the planetary symbols in earlier sources, used to represent the gods associated with the classical planets. Bianchini's planisphere, produced in the 2nd century, 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 modern sun symbol, pictured as a circle with a dot (☉), first appeared in the Renaissance.

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