Why did the Romans name the planets Mercury, Venus, Mars, Jupiter, and Saturn after their gods? Or did they consider these planets those gods?
The Romans were not the first and only to apply this practice. The seven classical planets (visible to the naked eye, 5 of which today are considered actual planets) were named after deities in Sumerian, Akkadian, Egyptian, and Chinese astronomy long before the Greek/Roman nomenclature.
These five planets were identified with the gods of the Babylonian pantheon as follows:
- Jupiter with Marduk,
- Venus with the goddess Ishtar,
- Saturn with Ninurta (Ninib),
- Mercury with Nabu (Nebo),
- Mars with Nergal.
In Ancient Egypt, the sun and planets were associated with deities as well:
- The Sun with Ra,
- Mercury with Seth,
- Venus with Khepri,
- Mars with Horus the Red,
- Jupiter with Horus who illuminates the Two Lands,
- Saturn with Horus, Bull of the Sky
As for the specific naming of the planets in Latin, the strongest influence is, of course, the Greek nomenclature (which itself is influenced by Indian astronomy). The naming is an exact match for the Roman equivalents of the Greek deities except for Saturn, which the Greeks named after a Titan.
- Sun – Helios: the Greek name of the Sun, the center of our solar system.
Earth – Ge (from the ancient Greek name Gaia or Gaea). Gaia was the great mother of all, creator and giver of birth to the Earth and all the Universe, the heavenly gods, the Titans, and the Giants. The gods were born from her union with Uranus (the sky), while the sea-gods were born from her union with Pontus (the sea).
Mercury – Ermis: the Greek name of the planet Mercury, which is the closest planet to the sun. It is named after the Greek God of commerce, Ermis or Hermes, who was also the messenger of the Ancient Greek gods.
Venus – Aphrodite: the Greek name of the planet Venus, which is named after Aphrodite, the goddess of Love.
Mars – Aris: the Greek name of the planet Mars, the fourth planet from the sun, also known as the Red planet. Aris or Ares was the Greek god of War.
Jupiter – Dias: the fifth planet from the sun, is the largest planet in our solar system. In Greek the name of the planet Jupiter is Dias, the Greek name of god Zeus. Jupiter has many moons orbiting around the planet. The largest one is Ganymede and it is named after Ganymedes, the hero of the Greek mythology.
Saturn – Kronos: the second largest planet of our system and the sixth planet from the sun. The Greek name of the planet Saturn is Kronos. The Titan Cronus was the father of Zeus, while Saturn was the Roman God of agriculture.
It is an interesting question as there are two sides to it: (1) history (2) language.
For the Mediterranean world the planets became really interesting with the spread of astrology during the Hellenistic times. It is easily seen that in classical Greece, e.g. Plato or Aristotle, just descriptive names are used: the bright one or the red one. The Romans were even less interested. Astrology came from Babylon and with the correspondence between gods already established. But that just moves back the question to the babylonians. Francesca Rochberg who is the expert on the topic writes in her The Heavenly Writing (Cambridge 2004, p.171)
Even in the cases in which the celestial bodies’ names duplicate the names of gods, such as is the case with the moon and sun, the celestial bodies cannot themselves be one and the same with the gods their namesakes.
There are a dozen pages discussing how a river, a wind, a mountain etc., received a proper name and was treated like a deity, a problem that has been much discussed in the early 20th. c. (Speaking of "primitive" or "prelogical" mentality was not politically incorrect back then.) How a particular planet came to be assigned to a particular deity does not seem to have a good answer. It is obvious however that astrological discourse developed mostly by glossing mythological names.
Why did the Romans name the planets after their gods?
According to Roman mythology, the Roman gods lived on Mount Olympos, in Greece.
Mount Olympus is the highest mountain in Greece. It is located in the Olympus Range on the border between Thessaly and Macedonia, between the regional units of Pieria and Larissa, about 80 km (50 mi) southwest from Thessaloniki. Mount Olympus has 52 peaks and deep gorges. The highest peak, Mytikas (Μύτικας Mýtikas), meaning "nose", rises to 2,917 metres (9,570 ft). It is one of the highest peaks in Europe in terms of topographic prominence.
Name and mythological associations
The origin of the name Όλυμπος Olumpos is unknown and usually considered of "pre-Greek" origin. In Homeric Greek (Odyssey 6.42), the variant Οὔλυμπος Oulumpos occurs, conceived of as the seat of the gods (and not identified with any specific peak). Homer (Iliad 5.754, Odyssey 20.103) also appears to be using οὔλυμπος as a common noun, as a synonym of οὐρανός ouranos "sky". Mt Olympus was historically also known as Mount Belus, after Iliad 1.591, where the seat of the gods is referred to as βηλ[ός] θεσπεσίο[ς] "heavenly threshold".
In Ancient Greek religion and mythology, "Olympus" was the name of the home of the Twelve Olympian gods of the Ancient Greek world. This was conceived of as a lofty mountaintop, and in all regions settled by Greek tribes, the highest local elevation tended to be so named; among the numerous peaks called Olumpos in antiquity are mountains in Mysia, Laconia, Lycia, Cyprus, Attica, Euboea, Ionia and Lesbos, and others. Thessalian Olympus is the highest peak in any territory with Greek settlement and came to be seen as the "Pan-Hellenic" representative of the mythological seat of the gods, by at least the 5th century BC, as Herodotus (1.56) identifies Olympus as the peak in Thessaly.
In Pieria, at Olympus's northern foot, the mythological tradition had placed the nine Muses, patrons of the Fine Arts, daughters of Zeus and the Titanide Mnemosyne.
Since the Romans believed that their gods lived on Mt. Olympus, the naming of the planets came from following the Babylonian tradition of doing so. They simply followed in the footsteps of this tradition from the Babylonians.
Most ancient cultures recognized seven “planets” consisting of sun and moon and the five planets visible in the sky. The Latin names of the Planets were simple translations of the Greek names, which in turn were translations of the Babylonian names, which go back to the Sumerians. Some interpretation was required for the Greek, and even for the Babylonian, translations, however. Nergal, for instance, was the god of war but also of pestilence and, especially, the Underworld —overlapping with the Greek Hades. While Kronos was the father of Zeus, Ninurta was the son of Enlil. The Babylonians replaced the Sumerian national gods Enlil and Enki with the patron god of Babylon, Marduk, and his son, Nabû — though Marduk was actually taken to be the son of Enki (called Ea in Babylonian). Ninurta, an obscure god inherited by the Babylonians, may have been identified with Saturn, the slowest moving visible planet, because, at least in one story, he was identified with the turtle. The ancient Egyptian, Sanskrit, and Chinese names for the planets are unrelated to the Sumerian. - Names of the Planets
In ancient times the planets were known as wanderers in the sky. For they seemed to move amongst the star and thus symbolized their movements amongst men with the names of their gods in the heavens.
Thousands of years ago, ancient civilizations turned to the heavens, marveling at their wonders. These ancient people worshipped various gods and often linked their gods with planets in the sky, which they considered to be “wandering stars.”
Mercury gets its name from the winged messenger of the gods. He was also the god of thievery, commerce, and travel. Most likely, the planet got its name from the rate at which it spins.
Venus was the Roman goddess of love and beauty, so it is a fitting name for this brightly shining planet. The only objects in our Solar System brighter than Venus are the Sun and the Moon. Ancient civilizations thought that Venus was two different objects – the Morning Star and the Evening Star. Other civilizations have also associated the planet with love. The Babylonians called the planet Ishtar after their goddess of womanhood and love.
Earth is the only planet not named after a Roman god or goddess, but it is associated with the goddess Terra Mater (Gaea to the Greeks). In mythology, she was the first goddess on Earth and the mother of Uranus. The name Earth comes from Old English and Germanic. It is derived from “eor(th)e” and “ertha,” which mean “ground.” Other civilizations all over the world also developed terms for our planet.
Mars is named after the Roman god of war. The planet got its name from the fact that it is the color of blood. Other civilizations also named the planets for its red color.
Jupiter was the Roman king of the gods. Considering that Jupiter is the largest planet in our Solar System, it makes sense that the planet was named after the most important god.
Saturn was named after the Roman god of agriculture and harvest. While the planet may have gotten its name from its golden color, like a field of wheat, it also had to do with its position in the sky. According to mythology, the god Saturn stole the position of king of the gods from his father Uranus. The throne was then stolen by Jupiter.
Uranus was not discovered until the 1800’s, but the astronomers in that time period continued the tradition of naming planets after Roman gods. In mythology, Uranus was the father of Saturn and was at one time the king of the gods.
Neptune almost ended up being named after one of the astronomers credited with discovering it – Verrier – that was greatly disputed, so it was named after the god of the sea. The name was probably inspired by its blue color.
Pluto is no longer a planet, but it used to be. The dark, cold, former planet was named after the god of the underworld. The first two letters of Pluto are also the initials of the man who predicted its existence, Percival Lowell.
Although the sun and moon are not a planets, they too also follows in the Romans imitating the Babylonian tradition naming system.
Apollo [Helios] was the god of the sun. Each day he drove his chariot of fiery horses across the sky to give light to the world. Apollo had a son called Phaethon, who was human. Phaethon nagged at Apollo to let him borrow the sun chariot and fly across the sky. Finally Apollo agreed. Phaethon proudly drove the sun chariot up into the sky, but then he lost control of the horses. The sun chariot dived towards the earth, burning everything. Finally Jupiter had to stop him with a thunder bolt.
Apollo was also the god of music, and played the lyre.
His most famous temple was at Delphi in Greece, see right. There, his priestess would prophesy the future. But she wasn't easy to understand. One day, a great king asked the priestess if he should invade a nearby kingdom. She said, "If you do this, a great kingdom will be destroyed." He thought that she meant he would be successful, and so started the war. He lost disastrously. It was his own kingdom that got destroyed! - Apollo
Diana was the goddess of the moon. Her twin brother Apollo was the god of the sun.
Diana carried a bow and arrows. She was the goddess of hunting. Once she was bathing in a forest pool. A hunter called Actaeon spied on her. So Diana turned him into a stag and he was chased by his own hunting dogs.
She helped women in child-birth, because her mother Leto gave birth to her and her twin brother so easily. - Diana
One must admit that as to the naming of the sun, some historical confusion does exist.
Sol is the personification of the Sun and a god in ancient Roman religion. It was long thought that Rome actually had two different, consecutive sun gods. The first, Sol Indiges, was thought to have been unimportant, disappearing altogether at an early period. Only in the late Roman Empire, scholars argued, did solar cult re-appear with the arrival in Rome of the Syrian Sol Invictus, perhaps under the influence of the Mithraic mysteries. Recent publications have challenged the notion of two different sun gods in Rome, pointing to the abundant evidence for the continuity of the cult of Sol, and the lack of any clear differentiation—either in name or depiction—between the "early" and "late" Roman sun god.
Sol Invictus (English translated as "Unconquered Sun") was long thought to have been a foreign state-supported sun god introduced from either Emesa or Palmyra in Syria by the emperor Aurelian in 274 and overshadowing other Eastern cults in importance, until the abolition of Classical Roman religion under Theodosius I. However the evidence for this is meager at best, and the notion that Aurelian introduced a new cult of the sun ignores the abundant evidence on coins, in images, in inscriptions, and in other sources for a strong presence of the sun god in Rome throughout the imperial period. Tertullian (died AD 220) writes that the Circus Maximus was dedicated primarily to Sol. During the reign of Aurelian, a new college of pontiffs for Sol was established.
Identification with other deities
The Greek assimilation of Apollo and Helios was already established in Rome by the end of the republic. Various Roman philosophers speculated on the nature of the sun, without arriving at any consensus. A typical example is Nigidius, a scholar of the 1st century BC. His works have not survived, but writing five centuries later, Macrobius reports that Nigidius argued that Sol was to be identified with Janus and that he had a counterpart, Jana, who was Luna. As such, they were to be regarded as the highest of the gods, receiving their sacrifices before all the others. Such views appear to have been restricted to an erudite elite—no ancient source aside from Macrobius mentions the equation of Sol with Janus—and had no impact on the well-attested cult of Sol as independent deity. - Sol (mythology)
In Etymologies bk. 8 §11 "Gods of the heathens (De diis gentium)," p. 185 (PDF p. 199), St. Isidore of Seville writes:
- By empty stories the pagans attempt to connect some of the names of their gods to physical causes, and they interpret these names as involved in the origins of the elements. But this has been entirely made up by poets, with the intention of enhancing their gods with certain figures of speech, while histories reveal these gods to have been lost and full of the infamy of shame. Indeed, when truth leaves off, room for fiction is wide open.
and ibid. bk. 3 § 50 "The standing of stars (De statu stellarum)":
- […] The Romans […] would point out the stars in the sky, and say that this one was Jupiter’s and that one was Mercury’s
Thus, it seems that the mythological stories and gods came first, and they were only later applied to real physical entities, such as the sun, moon, and planets.