Names from Antiquity
The planets visible to the unaided eye have carried names rooted in ancient mythology for thousands of years. Civilizations like the Greeks and Romans observed these celestial bodies, associating their movements and appearances with their pantheon of gods and goddesses. The names we use today largely stem from Roman mythology, often corresponding to Greek deities with similar attributes.
Mercury, the fastest-moving planet, was named after the Roman messenger god, known for his swiftness. Venus, the brightest object in the night sky after the Moon, received its name from the Roman goddess of love and beauty, reflecting its brilliant appearance. The reddish hue of Mars led to its naming after the Roman god of war, a color associated with conflict.
Jupiter, the largest planet, was named after the king of the Roman gods, the equivalent of Zeus in Greek mythology. Its immense size dominated the celestial sphere. Saturn, the slowest-moving of the ancient planets, was named after Jupiter’s father, the Roman god of agriculture and time. Its deliberate pace across the heavens evoked the passage of time.
Names from Discovery
The invention of the telescope revealed planets beyond those known to antiquity, leading to new naming challenges. Uranus was the first planet discovered with a telescope by William Herschel in 1781. Herschel initially proposed “Georgium Sidus” (George’s Star) in honor of King George III, but this name did not gain widespread acceptance.
Astronomers eventually adopted the name Uranus, proposed by Johann Elert Bode, to align with the mythological naming convention of the other planets. Uranus is the Latinized version of Ouranos, the Greek god of the sky and father of Saturn in mythology.
Neptune, discovered in 1846 through mathematical prediction before direct observation, also followed this mythological pattern. Several names were considered, but Neptune was quickly accepted. This planet was named after the Roman god of the sea due to its distant, deep blue appearance. Pluto, discovered in 1930 and now classified as a dwarf planet, was named after the Roman god of the underworld, a suggestion made by an eleven-year-old girl. Its distant and dim nature suited a deity associated with darkness and the unseen.
The Modern Naming Process
Today, the International Astronomical Union (IAU) is responsible for naming celestial bodies. Established in 1919, the IAU is the globally recognized authority for assigning names to stars, planets, asteroids, comets, and other celestial features. This organization ensures a systematic and consistent approach to astronomical nomenclature.
The IAU’s naming conventions often draw from various categories, though mythological themes remain prominent for many objects. For instance, newly discovered dwarf planets, trans-Neptunian objects, and their moons frequently receive names from mythologies across different cultures.
Beyond mythology, other naming conventions include honoring discoverers, significant scientists, or places relevant to the object’s discovery. For example, some asteroids are named after famous individuals or cities. The IAU’s process involves proposals from discoverers, which are then reviewed and approved by specialized working groups to maintain order and avoid duplication in the ever-expanding cosmic catalog.