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Gods of the Solar System on Roman Coins

You can click on any coin image to see the full coin.

There are eight planets in our solar system, and a ninth body that was called a planet until 1996. All but the Earth are named after Roman deities, and there are also deities who represent the Earth and the Moon.

The reverse of an antoninianus of Probus showing a facing view of Sol in a quadriga Sol driving a quadriga towards the viewer.

The Greeks and Romans knew five planets, which they thought of as wandering stars; in fact, the word comes from the Greek πλανητης (planetes), meaning "wanderer." Although some of the planets were unknown to the Romans, all but one of these deities are represented on Roman coins.

The Sun

But before we get to the planets, what about the centre of the solar system, the body after which it is named, our sun? 93 million miles away, so far that it takes eight minutes for its rays to reach us, yet still the source of almost all our light and life. (*)

Obviously, there is no question about when the sun was discovered!

The sun was a major deity to many cultures, including that of Rome. Here is Sol, the Invincible Sun, on an antoninians of Probus.

Rays of light surround his head, and he is driving the chariot which carries him across the sky. He appears on many Roman coins. His Greek equivalent was Helios, who also appeared on coins; particularly those from Rhodes, which had a colossal statue of Helios.


The reverse of a billon antoninianus of Gallienus showing Mercury Mercury with purse and caduceus.

The planet closest to the sun is Mercury. Small, with a fast orbit, bright but hard to spot because it appears so close to the sun.

Before the fourth century BCE, the Greeks thought it was two bodies, one seen in the morning and called after Apollo, the other seen in the evening and called after Hermes. The Romans gave the planet its current name; the deity Mercury is the Roman eqivalent of Hermes.

Mercury, and Hermes, appeared on many coins, like this antoninianus of the emperor Gallienus. For clothing, he has only a short chlamys which hangs from his arm. This nudity is typical of gods and heroes.

His head bears, not a hat, but actual wings; they symbolise speed, appropriate both for the messenger of the gods and for the planet which moves most swiftly around the sun.

He is carrying his herald's wand, called a caduceus, and a purse, which symbolises his role as a god of trade, which follows from his travel. These items are absolutely typical for images of Hermes and Mercury.


The reverse of a silver denarius of Julia Domna showing Venus Semi-nude Venus.

Venus is the second planet out from the sun, and it has always been a planet of mystery, shrouded in impenetrable clouds. It is the second brightest object in our night sky, after the moon.

It is both the morning star and the evening star, always appearing close to the sun. It was probably Pythagoras, in the 6th century BCE, who realised that these were a single body, which was said to belong to Aphrodite, the Greek goddess of love and beauty. Venus is the Roman equivalent of Aphrodite.

And the goddess Venus appeared on quite a few Roman coins, usually on coins of empresses or other members of the ruling family. This made an equivalence between the empress and the beautiful (and sometimes victorious) goddess.

On this coin of Julia Domna, the Syrian wife of the North African emperor Septimius Severus, Venus is seen from behind, so that she can be partly nude and still retain some modesty. She is leaning casually on a column with legs crossed, a pose that indicates perfect ease. The column also give an excuse for her garment to be disarrayed; you can see that it is caught and has been partly pulled away from her body.

She is carrying an apple, an appropriate gift from a beauty, and a palm branch, the award for a victor in a contest. The legend on this coin is VENERI VICTR, (dedicated to) Venus the victorious, so the palm in this case indicates a military victory.

The Earth and The Moon

To the Greeks and Romans, of course, the Earth was not a heavenly body, but their home. But the Romans had a Mother Earth deity, called Terra Mater or Tellus.

The reverse of a silver denarius of Hadrian showing Tellus. Tellus cultivating grain.

You will probably know the word Terra from phrases like "Terra firma," meaning solid earth as opposed to the shifting sea. The word Tellus is much less well known. As a name for the Earth, is probably only used in science fiction; for example, C. S. Lewis' so-called "Space Trilogy." The word was also applied to the name of the element tellurium.

The reverse of a billon Alexandrian tetradrachm of Claudius II Gothicus showing Selene and a lunar crescent Selene facing a lunar crescent.

On the left is a denarius of the emperor Hadrian which shows the goddess Tellus holding a rake and a plough, cultivating grain.

The legend is TELLVS STABIL, and is thought to refer to the stability which Hadrian brought to the Roman empire.

The moon, on the other hand, was most definitely a celestial body. It was Selene to the Greeks, and Luna to the Romans. These names occur in several combinations in modern times. Selene gave her name to the element selenium, which was discovered in 1917, in association with tellurium. Luna's name was given to the madness which was thought to be infuenced by the moon's phases.

The coin on the right is an Alexandrian tetradrachm of the emperor Claudius II. Being from an eastern, Greek-influenced culture, it shows Selene rather than Luna, gazing at the large crescent which is her symbol.

There were also many Roman coins which showed the goddess Diana in her role as a moon deity.


The reverse of a follis of Constantine the Great showing Father Mars who Fights for Us Father Mars in a fighting pose.

The next planet out from the Earth is Mars, the red planet, long associated with war. To the Greeks, it was the planet of Ares.

The planet is dry and almost certainly completely lifeless, though some have thought to see signs of life there. The astronomer Giovanni Schiaparelli claimed to see an elaborate network of canals on Mars, and this led to endless speculation about who, or what, might have made them. But they turned out to be nonexistent.

Mars has two small moons, which were not discovered until 1877; but they were given fitting names, Phobos and Deimos, meaning Fear and Dread. In Greek mythology, these were sons of Ares.

Rome was a warlike nation, and Mars appeared on a great number of Roman coins, in many guises; the protector, the champion, the victor, the peacemaker, the avenger, the preserver, and just the god, sometimes in his temple.

The coin on the left shows Mars the Champion, the one who fights for us. Like Mercury above, he is heroically nude. He stands in a fighting pose, with helmet, shield and spear.


The reverse of a follis of Constantine showing Jupiter Jupiter with eagle and victory.

Between Mars and Jupiter are thousands of small bodies, the asteroids. There are quite a few with names of deities that can be found on ancient coins; Ceres, Pallas, Juno, Vesta, Hygeia, Irene, for example. But they were unknown before 1801 and are too small to be regarded as planets, so I will pass over them.

Jupiter is the fifth and the largest planet, and is usually the third brightest object in the night sky. It was called Dios by the Greeks, an ancient form of the name Zeus, the Greek equivalent of Jupiter, who was the chief god of the Roman pantheon.

Like the next three planets out from the sun, Jupiter is composed mostly of the gases hydrogen and helium, with no solid surface that we can detect. It has the interesting property of radiating more heat than it receives from the sun. The energy for this radiation comes from contraction; it loses about 2cm of diameter each year.

Fascinating though this may be (to some of us), it has nothing to do with the coin on show here, which is a follis of the emperor Constantine the Great. It shows the god Jupiter leaning on his sceptre. By now you will be familiar with his godly nudity.

In his right hand, he holds a statuette of winged Victoria, who is standing on a globe and holding out to him the victor's wreath. This represents victory over all the cosmos, a rather overblown but typically Roman claim. The eagle at his feet is his signifier, and it too is holding out a wreath.

The legend on this coin, IOVI CONSERVATORI AVGG NN, means (This Coin is Dedicated To) Jupiter, Preserver of Our Emperors.


The obverse of a silver denarius of Lucius Memmius Galeria showing the head of Saturn. The head of Saturn with a harpa.

Saturn is the second largest planet, and is a gas giant like Jupiter. We know that it has a spectacular series of rings, because we have seen close-up photographs, but these were unknown to the Greeks and Romans, and were actually first seen by Galileo Galilei in 1610, using a telescope.

It was the outermost of the five planets known to the ancients, and to the Greeks it was the planet of Kronos, a god of agriculture, the child of Gaea (the Earth) and Ouranos (the sky).

Kronos carried a sickle which he used to castrate and replace his father. This same sickle was also symbolic of his agricultural role.

The Roman equivalent of Kronos was, of course, Saturnus. The coin on the right, a silver denarius from the Roman Republic, shows the head of Saturn, with his toothed and curved sickle behind his head.


Uranus, another gas giant planet which is named for the Greek gods of the sky, was unknown to the ancients; it was discovered in 1781 by the astronomer William Herschel. The Roman equivalent of Uranus was Caelus; but this the only planet whose name deity does not appear on a Roman coin.


The reverse of a billon antoninianus of Postumus showing Neptune holding a dolphin Neptune holding a dolphin.

Neptune is the seventh planet from the sun, and was also unknown to the ancients. It is a gas giant like Uranus. Neptune and Uranus both have a different composition from Saturn and Jupiter, containing more water, ammonia and methane.

It was first seen in 1846 by the astronomer Johan Galle, who was searching in a position which had been calculated by Urbain le Verrier based on peturbations in the orbit of Uranus.

It is named after the Roman god of the sea, who was important to an empire which encompassed the Mediterranean and relied on sea transport for conquest and provisioning.

The coin is an antoninianus of the breakaway emperor Postumus, who ruled Gaul and Britannia. It shows a very typical picture of the god, holding his famous trident in his left hand and with a dolphin wriggling on his outstretched right arm.

Like the other gods shown here, he is heroically nude. The sketchy outline of a boat in front of him is probably a Rhine river boat, an important mode of transport for this particular emperor and his fragment of an empire.


The reverse of a silver antoninianus of Caracalla showing Pluto-Serapis and Cerberus Pluto-Serapis and Cerberus.

Pluto was discovered by Clyde Tombaugh in 1930, but it was always an oddity; too small and with an orbit too eccentric to be quite what was expected in a ninth planet. In fact, though most of its orbit is in the ninth position, betwen 1979 and 1999 it was actually closer to the sun than the orbit of Neptune! (A factoid that somehow I have never had the chance to impress anyone with).

Pluto is no longer considered a planet, although it was for most of my life. Since 1996 it has been designated a dwarf planet. It is about one fifth the size of our moon, and smaller than some of the asteroids that orbit between Mars and Jupiter.

Pluto was named after the Roman god of the underworld, their equivalent to the Greek Hades. The name was suggested by an 11-year-old schoolgirl, Venetia Burney. The god Pluto appears on a few Roman coins, usually with his characteristics combined with Serapis, an Egyptian deity who was quite popular in Rome.

The coin on the right is an antoninianus of Caracalla, and shows Pluto-Serapis seated on his throne, one hand held out towards his dog. On his head is a kalathos, a Greek corn-basket that was typical of Serapis.

The dog is unusual in that it has three heads. This monstrous creature is Cerberus, the guardian of the underworld. Good dog!

*The exceptions are some rare types of life that subsist on heat and chemicals, such as those from the deep-sea hydrothermal vents known as black smokers.

The content of this page was last updated on 2 November 2010

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