By Adam Stevens
We’ve been discovering a lot of exoplanets recently. They have such exciting names as HD 189733 b, or Gilese 581, or sometimes vaguely amusing ones like OGLE-2006-BLG-109Lb (ha ha). The most exciting ones, like those that inhabit the habitable zone of their star, and that could be like our own little Earth, get extra special names. Like Kepler-22b.
There are people that want to change this. A paper in 2009 petitioned for exoplanets to be named with a little more imagination, along the lines already established for naming planets and stars. So many of the astronomical objects that we know of are named for the myths and legends of ancient Earth; why shouldn’t this continue? The IAU, the regulatory body for the naming of things we find in space, oppose the idea of ‘naming’ the new planets that we discover, mainly because the are likely to be so many that we would soon run short of names. Yet these exoplanets are given names, just rubbish ones that tell non-astronomers absolutely nothing about them.
Does the name we give them really matter, other than offering a way of relating these strange astronomical objects to things that we mere mortals know, offering us a way of picturing these planets in our mind’s eye?
The practice of naming objects in the sky for characters from myth and legend dates back, at least in the West, all the way to the Greeks and Romans. What primary school classroom would be complete without an atlas of the planets, secretly listing a portion of the pantheon of old Roman gods?
Mercury, messenger god with winged sandals, and the planet that moves fastest across the sky. Venus, the bright and beautiful morning star, also the goddess of love and beauty. Mars, god of war, the spot of blood red that wanders the night. Jupiter, king of the gods and king of the planets, protector of the solar system. Saturn, the furthest planet visible to the ancients, which the Greeks made sacred to Cronos, father of Zeus, the Romans eventually doing the same. These names have survived for more than two thousand years.
In those days, before the invention of the telescope, these were the only wanderers visible in the night sky. Later, when astronomers found more ‘planetes’, the Roman system of naming was already in place, so that despite the protestations of their discoverers (Herschel wanted to name Uranus after King George III) we ended up with the outer planets Uranus, Neptune, and, eventually, Pluto.
The power of this naming convention went even further. When the two moons of Mars were discovered, they quickly became Phobos and Deimos, the war god’s attendant sons. The moons of Jupiter are all named for his (numerous (and not necessarily female)) lovers. Saturn’s moons are named for his brother Titans; Iapetus, Tethys, Dione, and, er, Titan…
At this point, though, the astronomers must have been starting to run dry of appropriate Greek and Roman myths, or at least getting bored of them. The moons of Uranus, then, are named after spirits from literature (mostly Shakespearean), like Oberon, Ariel, Miranda, and Ophelia.
Even then, we are left with many unnamed objects left in the solar system. The smaller moons, the asteroids, the comets; the most notable of these all carry names, some following the same Roman system.
More importantly, these already titled bodies are not just featureless balls floating through space. They have complex surfaces, landscapes covered in strange and wonderful features. So next up, astronomers had to devise a system for naming planetary features, and this is where they really went to town.
Some of the systems have some kind of logic.
The surface features of Venus are all, appropriately, named after famous women, sometimes real, sometimes fictional. What this says about poor old James Clark Maxwell, who has a venereal (yes, you read that right) mountain range named after him, is anyone’s guess.
The craters on the asteroid Eros are named for famous lovers.
The tortured and chaotic surface of Io is covered in the names of fire and sun gods from a multitude of ancient cultures.
Others are somewhat random, maybe because their namers ran out of good ideas, or because they were being playful: the fractured ice crust of Europa bears a heavily Celtic influence, whereas Ganymede is a melting pot of Phoenician, Babylonian and Egyptian names, both for no apparent reason.
Some give us a glimpse of some strange senses of humour. The bleak surface of Mercury is covered from horizon to horizon in craters named after famous artists. Titan, with its thick atmosphere, lakes, and rains of liquid methane has a number of features named for rain gods and, for no apparent reason, others after gods of happiness. Perhaps it’s the weather.
These planets and moons show all the eccentricities of town planners that name the streets of a new town after their own personal interests, likes, or random topics vaguely associated with the location.
Yet none of them match the idiosyncrasy of Mars.
Details of the red planet are easily observable with even a moderately powered telescope, and so names have been assigned to these features for hundreds of years. In fact, the system we use today owes a heavy debt to the observations and imagination of Giovanni Schiaparelli, the man who gave us the “canali.”
If you look at Mars, it is easy to pick out areas of light and dark, known as ‘albedo’ features. Seeing these vast continents, pools or fractured channels of dark red on the martian landscape, Schiaparelli went about naming. Who knows what guided his thoughts, but the names of his albedo features were drawn from influences far and wide.
Some came from classical antiquity, Olympus Mons being a prime example; the home of the gods and largest mountain in the solar system. Yet many seem totally random. Olympus Mons’ neighbours, the other Tharsis volcanoes are named, respectively, after Schiaparelli’s original Peacock lake, Rural lake, and an old Roman forest.
No matter how random, though, these names and the ones that followed them have a lyrical quality. Tempe Terra, the land of time; Promethei Sinus, bay of Prometheus; Ophir Chasma, valley of gold, and so on.
Later, with more powerful telescopes, and close up photographs of the planet, we began to see more of the details of Mars, and many of Schiaparelli’s conventions were followed. Now Mars is covered in valleys, plains, mountains named after many features on Earth. The major craters are named after famous scientists.
So if you were to look into the meanings of all these names, this “system” would probably seem mad or, at the very least, utterly arbitrary.
These names form the language of Mars and, with their fellows on other bodies, they form the language of our solar system. They evoke a past age, of a time when the gods walked amongst men, when the stories of heroes were told around fires and passed down from generation to generation. Others recall the age of exploration, when scientists were changing the world almost every day, spreading the knowledge of humanity throughout the universe.
To science, the names don’t matter. They are only designations, for ease of reference, to differentiate similar things.
For the rest of us though, these names do matter. They tell a story, a great story, of how far our species has come, but continue to remind us of where we came from.
It is sad then, when these names come into dispute. The Mars Science Laboratory, Curiosity, is due to land in Gale Crater on Mars soon. Its mission is to explore the central uplift peak of the crater, a moderately large mountain that might tell us much about the process that shaped the surface of the planet.
Before it gained notoriety, this summit hadn’t been given an official name, so the scientists working on the mission had named it after Robert P. Sharp, one of the founders of the field of planetary science, a fitting memorial for a man who spent much of his life researching Mars. Recently, though, the IAU, those responsible for those horrible Exoplanet designations, have renamed Mount Sharp to follow the standard convention, and now Curiosity will be exploring Aeolis Mons.
Yes, the system was in place, and is helpful in that it provides consistency. But peek under the lip of this consistency and you find a mass of contradiction and whimsy, so does it really matter that much?
Well, it matters to those that worked with Sharp, those who named a mountain after him. It matters to those of us that want to excite people about the discovery of planets outside our solar system. The names do matter, but they matter more in our hearts than in our head. These names are a tool to tie the real exploration of the universe to our great gift – imagination.
(Postscript: The IAU have named a crater, near Gale, “Robert Sharp” (as there was already a Sharp Crater), following their system and still preserving this legacy somewhat.)