There are eight planets in our solar system; four rocky inner worlds, two gas giants and
two ice giants.
Then there are dwarf planets (including Pluto), many, many moons, and a huge number of asteroids
and other rocky or icy bodies.
Across human history we’ve charted and recorded our particular corner of space as best we
can, but why exactly do we label the solar system as we do?
This is Unveiled and today we’re uncovering exactly how the planets got their names.
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The planets orbiting our star, Sol, are generally known as, in order out from the sun; Mercury,
Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
In school we’re often taught various mnemonics to remember those names, but we don’t so
often think about where they came from.
And, to find out, we need to step back into ancient history.
Some of the first civilizations to study the solar system were the ancient Sumerians and
Mesopotamians, more than 6,000 years ago.
The five planets closest to the sun, besides our own, are visible to the naked eye and
so (naturally) they were the first to be named - and we believe for the Sumerian gods.
It’s thought that what we now call Mercury was once known as Enki, aligning it with the
god of knowledge and creation.
Venus was called Inanna, after the Sumerian goddess of sex.
And Mars may have once been named for the underworld figure Gugalanna, or for Nergal;
the god of death and war.
We know that Jupiter is the largest solar system planet, so it’s perhaps unsurprising
that it was associated with Enlil, who was the king of the Sumerian gods... while, Enlil’s
son, Ninurta, the god of harvests, was equated with Saturn.
Early understandings of the solar system also often had other celestial bodies like the
Moon and even the Sun itself as “planets”, as well - interpretations which obviously
shifted over time - but we can at least begin to build a picture of how our ideas on space
started to form.
The Babylonian civilization, which also intently studied the stars, inherited much of the cultural
knowledge of its forebears - but further developed planetary theory.
Today, some of the earliest physical records of the planets date back to the Babylonians,
at some 2,000 years BC.
While the names of most of the gods (and therefore planets) changed, their roles were often quite
similar.
Ninurta remained the name for Saturn, but the chief god was Marduk, so Jupiter inherited
that name instead of Enlil.
Mars was still associated with the god of destruction, Nergal.
Inanna was replaced with a similar fertility goddess, Ishtar… and Enki (today’s Mercury)
became Nabu, though Nabu was still the patron of knowledge.
These five gods, again along with the sun and moon, were worshipped as incredibly important
deities - so much so that the Babylonians ascribed particular importance to the number
seven in general… which is also why, today, we have seven days of the week.
But then came the ancient Greeks and more significant changes, with the Greeks also
ascribing the names of their own gods to the planets.
Now, the planet closest to the sun was known as Hermes, after the messenger god (seemingly
because its speedy orbit around its star brought to mind Hermes’ fleetfooted reputation).
What’s now Venus was then named for Aphrodite, aligning it for a third time with a goddess
of love or fertility.
Similarly, Mars was again named for the god of war, in this case, Ares… and the solar
system’s largest planet was named after another king of the gods, in Zeus.
Meanwhile, to slightly break with tradition, what’s now Saturn was actually named for
Zeus’ father, Cronus.
The final major changes came with the rise of the Roman Empire, however.
As this mighty, sprawling nation absorbed the knowledge of prior groups and its surrounding
lands, it built a culture (whether through conquest or cultural absorption) that - where
the planets were concerned - led to some more recognisable terms.
The Greek and Roman gods were ultimately very similar (even more so than the gods between
previous civilizations), but the Roman’s gave their deities another slew of different
names.
It’s here that we see the more familiar planet names appear: Hermes became Mercury,
Aphrodite became Venus, Ares was Mars, Zeus was Jupiter, and Cronus became Saturn.
And, for those five planets at least - the originals - that’s how it remained.
But why, after so many iterations before them, was it the Roman names which stuck?
Well, Latin (the language the Roman planets were named in) has also been the language
of the Catholic Church for centuries and centuries...
Today, it’s one of the most influential languages over modern-day English, preserved
by the Church but felt across all aspects of society.
However, in an alternate history the Roman planets may still have fallen out of favour
during Medieval times in Europe.
Obviously they didn’t, and that’s because it’s thought that “Mercury thru to Saturn”
may have also have been preserved across the Middle East, at a time when Islamic astronomers
continued studying and recording the stars while Europe fell into the Dark Ages and science
was (in some quarters) denounced.
Eventually, however, the names we know were popularized by scientists in the early twentieth
century, who standardized Mercury, Venus, Mars, Jupiter and Saturn across the board.
So that’s five out of eight, but what about the rest?
The next planet to be discovered was the next planet out from Saturn, first formally catalogued
in 1781 by Sir William Herschel.
This planet, which Herschel originally mistook for a star (much like many others who had
seen it before him), was originally named Georgium Sidus, or “George’s Star”,
for the reigning King of England at the time - George the Third.
But Georgium Sidus wasn’t a popular pick outside of England, so several other names
were gradually put forward, with the one that stuck being Uranus.
Now the butt of many a classroom joke, the naming of Uranus actually did follow tradition
- with it being coined for the Greek god of the sky, who was also the father of Cronus
aka Saturn.
Finally, the Solar system’s eighth planet was, in fact, predicted before it was found.
It was mathematically assumed to exist thanks to the effects it had on the orbit of Uranus,
before it was eventually formally discovered in 1846.
While it was initially referred to (after its discoverer Urbain Le Verrier) as “Le
Verrier's planet,” scientists and astronomers were again quick to propose some more mythological
options for it, including Oceanus and Janus.
Ultimately, though, the scientific community settled on the name Neptune, after the Roman
god of the sea; a good choice given this planet’s distinct blue color.
A word for Pluto, though.
While it’s no longer considered a planet according to guidelines by the International
Astronomical Union, this tiny dwarf planet orbiting way past Neptune was also mathematically
predicted before it was discovered and first observed in 1930.
And, again, there was debate over what to name it, but this time the decision fell to
a member of the public, as an eleven-year old English girl with an interest in mythology
suggested “Pluto,” after the god of the underworld.
And, to prove just how influential planet-naming itself can be, the christening of Pluto may
have also inspired other things named around the same time, such as the chemical element
plutonium and Mickey Mouse’s pet dog.
But aren’t we forgetting something kind of… important?
Like, our own planet!
Despite the lofty and storied names behind most of the solar system’s other planets,
though, ours - “Earth” - is much more simply a plain English word for “ground”
or “soil”.
Granted, Earth has sometimes been personified as the Greek and Roman goddesses Gaia and
Terra (from which we get the phrase, “terra firma”), but for English speakers, the etymology
of the name of our own world is somewhat… dull by comparison – not to mention inaccurate,
since most of Earth is covered in water!
The alternative approach can be put down to a long-running cultural misstep, though.
For most of history, most people assumed that the heavens revolved around us, so naming
the world we inhabited wasn’t really something that we even thought needed to be done.
We just were; it was the other, distant worlds that most captured our interest!
In general, early civilizations actually equated the visible planets with their highest gods,
or else they just named them after them anyway.
And, as those beliefs were passed down through generations and across several cultures, the
names themselves went through multiple updates until they stuck.
In more recent times, the naming of the ice giants and other solar system bodies has also
been heavily influenced by classical beliefs - with most moons and even some asteroids
adopting ancient and divine names.
Ultimately, even today when we look to the heavens, we’re usually guided by those immortal
figures.
And that’s how the planets got their names.
What do you think?
Is there anything we missed?
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