Michael Hanlon

Science & Nature SpecialAstronomy

PC goes planetary

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One way to throw an astrologer into confusion – well, even more confusion than that under which they normally labour – is to find a new planet. When Clyde Tombaugh spotted Pluto in 1930, the third oldest profession found itself in a tizzy. So when a tenth planet, beyond Pluto, was announced a few months ago, the astrologers again let out a collective groan and started redrawing their charts. But it isn't just the stargazing charlatans who were bothered by the new discovery; the rest of us were just as bemused, not by the planet itself but by its name.

Quaoar. Qua-oh-what? Hard to spell, harder to say. The only person I know who can pronounce Quaoar properly is a small boy who had to present a talk on the thing to his classmates. Which is a shame, because although Quaoar is by all accounts a miserable piece of cosmic real estate, made essentially of snow and so cold that nothing moves and nothing stirs, as only the tenth planet ever discovered in our solar system it surely deserves an exciting name.

But snappy names, it seems, are in short supply. Fashion, political correctness, national pride and sheer whimsy have already been reflected in the skies. And, with huge new telescopes coming into service and new discoveries seemingly being made every week, the biggest problem of all is upon us – we are starting to run out of names altogether.

In the old days, it was all so simple. The ancients could see only a few thousand objects in the sky. To the Egyptians, Ra, the Sun, was the sun god. The Greeks named the planets, the wandering stars, after their gods, the names later being romanised into the familiar words we know today: Venus, Mars, Jupiter and the rest. The advent of the telescopic age in the 17th century sparked a naming frenzy for the heavens. The Polish astronomer Johannes Hevelius saw, in the 1640s, a mirror image of the Earth on the Moon. He paid homage to his fellow astronomers, naming the Sea of Kepler, the Lake of Galileo and the Ocean of Copernicus. Hevelius thought that if you turned the Moon on its side, the light and dark patches were reminiscent of the Roman and Greek classical world. So the Moon acquired an Arabia, a Caspian Sea and a Mediterranean. He added Africa, the Alps and Caucasus.

Nowadays, when something gets named, it stays named. But in the 17th century, when astronomers fought for prestige like jousting knights, the Moon found itself renamed in haste by an Italian monk called Giovanni Riccioli. It was he who gave us the evocative names that we know today, Mare Tranquillitatis and Mare Crisium (the Seas of Tranquillity and Crises), the Sea of Showers and the Sea of Nectar.

In front of me I have a globe of the planet Mars. Produced largely from photographs taken by the Viking space probes in 1976, it evokes an ethereal, almost imaginary world. Schiaparelli's canali are not there, still less Lowell's imagined canals, but we have Mount Olympus, the Land of Prometheus and the Arcadian and Utopian Plains.

The old tradition of naming the heavens in Latin, usually after figures of classical antiquity, continued into the 20th century. When, in 1978, it was discovered that Pluto, the god of the underworld, had a moon, it was logically named Charon, after the ferryman who rowed souls across the Styx.

In the past few decades – since the advent of space probes – the Paris-based International Astronomical Union (which has policed the nomenclature of the solar system for 83 years) has abandoned its old classical ways and come up with a bewildering array of names based not only on gods but on poets, astronomers and even journalists.

The IAU rules are simple. Planets and moons are given themes, and the names should reflect this. Thus the landscapes of Venus, always seen as a girly sort of place, are almost universally named after women. The IAU also stipulates that naming should be 'international'. Interestingly, the astronomers' rules also stipulate that 'no names having political, military or religious significance may be used, except for names of political figures prior to the 19th century'. Take Venus, for example. Nowhere on this ghastly planet had a name until recently, for the simple reason that its entire face is covered in clouds. But then radar soundings were taken and probes sent to peer through the murk, and a bewildering array of mountain chains, craters and plains emerged, all ready to be named.

And what names they chose! The Addams crater, for example, is named after one Jane Addams, a 20th-century American social reformer and peace activist. Another crater is called Al-Taymuriyya, after an Egyptian feminist. Another geological feature is named after Georgette Chapelle, an American photographer killed in the Vietnam war. Despite the 'international' requirement, there are an awful lot of obscure American worthies here.

While Venus is as politically correct as it can be, Jupiter's moon Io was shown by the Voyager and Galileo space probes to be a place of gargantuan volcanoes, with rivers of brimstone, mile-high fire-fountains and lakes of white-hot lava, and its canyons and mountains have been named after suitably butch figures. Thus we have a volcano named after the Japanese fire god, Masubi, and another named after the Icelandic lord of lava, Surt.

Who or what, then, was Quaoar? It turns out he/she was a Native American deity, a force associated with the creation of the world and its shaping forces. An impressive being, then, if not as slippery off the tongue as Persephone, a rival classical name for the tenth planet.

It is probable that the work of the IAU naming committee will get even harder in years to come. The problem is simple: astronomers are discovering new stuff at an increasing, exponential rate. New stars and galaxies are not a problem as such; only a handful of bright, visible stars have traditional, mostly Arabic names (Betelgeuse, Alcor and so on); the rest are simply numbers. (Anyone offering to 'sell' you a star that you can name is a con-merchant. No one owns the stars, or bits of the Moon or Mars for that matter, and, as we have seen, naming is solely in the hands of the IAU.)

But new planets and parts of planets pose a real problem. You can't walk on a star, so a number will do. But planets are places. The solar system has ten, plus a few hundred sizable moons and asteroids that demand a name. Then you have to name all the pockmarks and blemishes on these objects.

It is only going to get worse. Since 1995, more than 100 planets have been discovered orbiting nearby stars. We don't know much about these planets; but we will, when bigger and better telescopes are built. By 2020, we might have ten thousand new planets to name, and a couple of decades or so later we may be able to start picking out continents and seas on these places – and pretty soon there will be no gods/goddesses/peace campaigners/feminists left. Perhaps we will have to turn to science fiction. If we find a dry and dusty desert world orbiting some far-off star, maybe we should name it Tatooine after the home of Star Wars' Luke Skywalker. Or what about Planet Vulcan? But whatever we decide to call these new worlds, the astrologers back on Earth are going to have an awful lot of explaining to do.

Michael Hanlon is a science writer at the Daily Mail and is currently writing a history of Mars.