The five planets visible without a telescope received their current English names from the ancient Romans, who named them after gods in their pantheon, but the practice of naming those bright wandering lights stretches back even further, to the Babylonians and Sumerians of the third millennium BCE. The later discoveries of Uranus, Neptune, and Pluto each triggered their own naming disputes, resolved through a mix of astronomical tradition, national pride, and eventual consensus. The story of planetary names is really a story about how different civilizations saw the sky and claimed it.
The Five Wanderers of the Ancient World
Mercury, Venus, Mars, Jupiter, and Saturn are all bright enough to spot with the naked eye, and ancient skywatchers noticed something odd about them: unlike the fixed stars, these five lights moved against the background constellations over weeks and months. The Greeks called them “asteres planetai,” meaning wandering stars, which is where the word “planet” comes from. But the Greeks were not the first to track them. Babylonian astronomers in Mesopotamia had been systematically recording the movements of these objects since at least the second millennium BCE, and possibly earlier. Babylonian tablets from around 1600 BCE contain detailed records of Venus’s appearances and disappearances near the horizon.
The Babylonians associated each planet with a deity from their own religion. Jupiter was linked to Marduk, the chief god of Babylon. Venus was Ishtar, goddess of love and war. Saturn was Ninurta, Mars was Nergal (god of the underworld and plague), and Mercury was Nabu, the god of writing and wisdom. These divine associations were not casual: the Babylonians believed planetary movements carried messages from the gods, and priestly scholars devoted enormous effort to interpreting them.
From Babylon to Greece to Rome
When Greek astronomers inherited Babylonian astronomical knowledge, they remapped the planets onto their own gods. The pattern of association tended to follow function. Ishtar was a love goddess, so Venus became Aphrodite. Marduk was the king of the gods, so Jupiter became Zeus. Nergal was fearsome and warlike, so Mars became Ares. Mercury, the swift messenger, became Hermes. Saturn, the slowest-moving planet, became Kronos, the old father of the gods.
The Romans then did the same thing one more time, substituting their own equivalent deities. Zeus became Jupiter. Ares became Mars. Aphrodite became Venus. Hermes became Mercury. Kronos became Saturn. Because Latin became the dominant language of European scholarship for over a thousand years, the Roman names stuck in English and most Western European languages. French, Spanish, Italian, and Portuguese all use versions of the same Latin names, though the connection is more obvious in some languages than others.
Interestingly, several Germanic and Norse languages took a different path with the days of the week. In English, Tuesday, Wednesday, Thursday, and Friday come from Norse gods (Tyr, Odin, Thor, and Frigg) rather than the Roman gods associated with those days’ planets. But the planet names themselves remained Latin in English. Nobody in the English-speaking world calls Mars “Tyr’s star.”
What Indian and East Asian Traditions Called the Planets
Western European names are not the only game in town. Indian astronomical traditions developed their own planetary terminology, often rooted in Sanskrit. The Gārgīyajyotiṣa, one of the oldest sources of early Indian astral science, contains extensive material on celestial omens and planetary science that was later cited in influential works across both Hindu and Buddhist traditions.1History of Science in South Asia. Vedic Astral Lore and Planetary Science in the Gārgīyajyotiṣa In Sanskrit, Mars is Mangala, Jupiter is Bṛhaspati, Saturn is Shani, Venus is Shukra, and Mercury is Budha. These names carry their own mythological weight and remain in everyday use across South Asia today, especially in astrology and the naming of weekdays in Hindi and other Indian languages.
Chinese astronomy likewise developed an independent naming system that tied planets to the five classical elements rather than to gods. Jupiter was the Wood Star, Mars the Fire Star, Saturn the Earth Star, Venus the Metal Star (or Gold Star), and Mercury the Water Star. Japanese, Korean, and Vietnamese naming conventions followed the Chinese model. These names are still the standard terms in those languages, and they reflect a fundamentally different way of organizing celestial knowledge: elemental rather than divine.
The point is that when people ask “who named the planets,” the answer depends entirely on which language you are speaking. The planets have been named independently dozens of times by dozens of cultures. The English names just happen to be the ones that dominate international scientific communication, largely because the International Astronomical Union conducts its business in English and French, both of which inherited the Latin tradition.
Uranus and the First Modern Naming Battle
The five classical planets were known for millennia before anyone realized there might be more. That changed on March 13, 1781, when William Herschel, a German-born musician and amateur astronomer living in England, spotted an unfamiliar object through his homemade telescope. He initially thought it was a comet, but its nearly circular orbit soon made clear that it was a new planet, the first discovered in recorded history.
Herschel proposed calling it “Georgium Sidus” (George’s Star) in honor of his patron, King George III of England. This went over well in Britain and absolutely nowhere else. French astronomers, unsurprisingly, had no interest in naming a planet after the British king. Some suggested calling it simply “Herschel,” after its discoverer. The German astronomer Johann Elert Bode proposed “Uranus,” after the ancient Greek god of the sky and father of Kronos (Saturn), arguing that this maintained the mythological family tree: Saturn was Jupiter’s father, and Uranus was Saturn’s father.
Bode’s suggestion gradually won out, though “Georgium Sidus” lingered in some British publications for decades. The name Uranus was widely accepted by the 1850s. The episode established an informal precedent that new planets should follow the Greco-Roman naming convention rather than honor living monarchs or their discoverers.
Neptune and the Power of Prediction
The discovery of Neptune in 1846 was nothing like the accidental find of Uranus. Astronomers had noticed that Uranus was not following its predicted orbit. Something unseen was tugging on it. Two mathematicians working independently, John Couch Adams in England and Urbain Le Verrier in France, calculated where a hypothetical planet would need to be to account for the gravitational discrepancies in Uranus’s motion.2Nature. John Couch Adams and the Discovery of Neptune When the German astronomer Johann Galle pointed his telescope at the spot Le Verrier predicted on September 23, 1846, Neptune was there, less than one degree from the predicted position.
The naming process was messy. Le Verrier initially wanted to name the planet after himself, then suggested “Neptune.” The British camp, feeling their man Adams had been unfairly sidelined, pushed back in various ways. Le Verrier also briefly tried to retroactively rename Uranus to “Herschel,” which would have given French and English astronomers one planet name apiece. None of these political maneuvers stuck. Neptune, the Roman god of the sea, became the accepted name within a few years, again following the mythological convention Bode had championed for Uranus.
Pluto, Its Demotion, and the Naming of Dwarf Planets
Clyde Tombaugh discovered Pluto on February 18, 1930, at the Lowell Observatory in Arizona. Percival Lowell had spent the final years of his life searching for a “Planet X” beyond Neptune, and while Tombaugh’s find was in roughly the right part of the sky, Pluto turned out to be far too small to have caused the orbital disturbances Lowell had been chasing. The name “Pluto” was suggested by Venetia Burney, an eleven-year-old schoolgirl in Oxford, England. Her grandfather, a retired librarian at the Bodleian Library, passed the suggestion to an astronomy professor, who cabled it to the observatory. The name fit the tradition (Pluto was the Roman god of the underworld, fitting for a cold, distant world), and it also conveniently started with the initials “PL,” honoring Percival Lowell.
For 76 years, Pluto was the ninth planet. Then, in 2006, the International Astronomical Union voted to create a formal definition of “planet” that Pluto did not meet, primarily because it had not cleared its orbital neighborhood of other debris. Pluto was reclassified as a “dwarf planet.” The decision remains one of the most publicly controversial acts in modern astronomy, though most planetary scientists accept the reclassification as reasonable. Pluto kept its name; it just lost its title.
The naming of other dwarf planets has continued to follow mythological convention. Eris, discovered in 2005 and slightly more massive than Pluto, was named after the Greek goddess of discord, a wry nod to the chaos its discovery caused in the planet-definition debate. Its moon was named Dysnomia (lawlessness). Haumea, Makemake, and Sedna drew on Hawaiian, Rapa Nui, and Inuit mythology respectively, reflecting a deliberate effort to move beyond the exclusively Greco-Roman naming tradition for new solar system bodies.
Who Decides Names Now
Since 1919, the International Astronomical Union has been the globally recognized authority on naming celestial bodies. For planets and dwarf planets, the process is relatively informal since new planet discoveries are exceptionally rare. The discoverer typically proposes a name, which then needs approval from the relevant IAU working group and, for something as significant as a planet, the IAU General Assembly.
The naming conventions for other types of solar system objects are more formalized. Asteroids can be named almost anything (within certain guidelines about length and taste), and there are asteroids named after cities, scientists, musicians, and fictional characters. Comets are traditionally named after their discoverers. Features on planetary surfaces follow thematic conventions: craters on Mercury are named after artists and writers, craters on Venus after notable women, and so on. Moons of the outer planets tend to follow mythological themes connected to the parent planet’s name: Jupiter’s moons are named after lovers and companions of Zeus, Saturn’s after Titans.
The key shift from the ancient world is that naming is now a bureaucratic process governed by international consensus rather than the organic work of cultures looking up and telling stories. A Babylonian priest-astronomer and an IAU committee are doing fundamentally different things, even when the end result is a mythological name on a dot of light.
The Question of a Ninth Planet Today
The possibility that a large, undiscovered planet lurks in the far outer solar system has resurfaced repeatedly in modern astronomy. The most recent version of this idea, based on unusual clustering patterns in the orbits of distant objects beyond Neptune, has been informally called “Planet Nine” or “Planet X.” If such an object is ever confirmed, it will need an official name, and the informal labels it currently carries are not strong candidates. A recent proposal in the astronomy literature suggests the name “Telisto,” from the ancient Greek word for “farthest” or “most remote,” arguing that a name should capture the object’s most defining physical characteristic: its enormous distance from the Sun, estimated at several hundred astronomical units.3Universe. A Modest Proposal for Naming a Hypothetical Distant Planet in the Solar System
Whether “Telisto” or any other name eventually wins out depends on whether the planet is found at all and, if it is, on the preferences of its discoverers and the IAU’s approval process. The naming could also break from the Greco-Roman tradition, as happened with some dwarf planets. But the mere fact that astronomers are debating what to call a planet that might not exist illustrates how deeply the act of naming is woven into the practice of astronomy. Finding the object is the science; naming it is the moment it enters human culture.
Why English Uses Roman Names While Other Languages Do Not
A common misconception is that the Roman names are the “real” or “official” names of the planets in some universal sense. They are not. They are the names used in English and a cluster of European languages descended from or heavily influenced by Latin. Mandarin Chinese speakers call Mars “fire star” (火星) with no reference to Roman mythology. Hindi speakers call it Mangala. Arabic speakers call it al-Mirrikh. Each name carries its own cultural associations and history, and none is more astronomically correct than any other.
The IAU does use Latin-derived names in its official catalogs and communications, which gives the Roman names a kind of bureaucratic primacy in international science. But this is a product of European dominance in the institutional history of modern astronomy, not a reflection of who “really” named the planets. The Babylonians did it first, and dozens of cultures did it independently. The Romans just happened to be the ones whose language became the medium of Western science.
Moons and the Expanding Name Game
When Galileo discovered four moons orbiting Jupiter in 1610, a new naming question opened up. Galileo called them the “Medicean Stars” after his patrons, the Medici family. The German astronomer Simon Marius, who claimed independent discovery around the same time, suggested the names Io, Europa, Ganymede, and Callisto, all figures from Greek mythology connected to Zeus. Marius’s names eventually prevailed, though it took over two centuries for them to become standard. For a long time, astronomers just referred to Jupiter’s moons by number.
As telescopes improved and more moons were found around Saturn, Uranus, and Neptune, the naming conventions developed along different thematic lines. Saturn’s moons got Titan names (Titan, Rhea, Iapetus, Dione). Uranus’s moons broke from mythology entirely: William Herschel’s son John suggested names from English literature, and Uranus’s moons are now named after characters from Shakespeare and Alexander Pope. Miranda, Ariel, Umbriel, Titania, and Oberon all come from the literary canon rather than ancient myth. Neptune’s moons returned to mythology, drawing on sea deities and water spirits to match the ocean god.
This patchwork of conventions gives the solar system’s naming landscape a surprisingly eclectic character. A single evening of moon-gazing can take you from Babylonian-influenced Roman mythology to Shakespeare’s “The Tempest” to Inuit oral tradition, depending on where you point your telescope.