05 January 2007

Pluto to Mars in Six Months

My second monthly column, "Santa Claus Conquers the Martians", is now up at the Surefish site. It's about life on Mars, responding (rather belatedly now) to the discovery of running water on the Martian surface back in December.

And they've started using my preferred title, Divine Invasions. Hurrah.

As a bonus extra (and following on from the "planet" theme), here's the first of the two sample columns I offered Surefish back in August to persuade them to take me on. (The second is what became my first Divine Invasions column, "It's Been Unreal".)

It's not usable now, because it's tied so explicitly to a particular moment in astronomical history. Crucially, it attempts to pre-empt the result of the I.A.U. discussions concerning Pluto, and gets the details wrong. You could probably date it to the day, if you studied the contemporary press predictions carefully enough.

On the understanding that most of the information in it is now out of date, though, we present...
Hell-Gods from Outer Space

Most of us know the story. There’s the hot one, the mysterious one, the motherly one, the red one, the great big one, the one with all the rings, the one with the rude name, the blue one and the cold one.

Sadly, the myth of the solar system’s nine planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, as they’re more formally known – has been exploded for good.

Pluto, the most recent to have been discovered, has been recognised as a planet since 1930 mostly because its discoverers knew rather less about the solar system than astronomers do now. This month [August 2006] the International Astronomical Union (IAU) has voted to recognise the fact, demoting Pluto to a new class of ‘dwarf planets’. It is joined there by the asteroid Ceres, by the recently-discovered 2003 UB313 (more memorably nicknamed ‘Xena’), and – in the ultimate indignity – by its own moon, Charon.

The debate only concerns definitions, and the new categories are simply those which astronomers consider most helpful in discussing celestial bodies. The only people who are actually likely to care are the disenfranchised astrologers (for whom Pluto governs power and corruption, thanks to the decade of history following its discovery) and the science fiction fans.

Pluto was discovered just as science fiction was taking off as a popular art form, and consequently the myth of the Nine Planets has contributed profoundly to its readers’ sense of our place in the cosmos. Stories have tended to depict Pluto romantically as the Solar System’s last outpost, a chilly, lonely world on which humanity might one day walk. (Neptune, the next one in, is a bad candidate for landing or colonisation, having a surface mostly made of gaseous hydrogen.)

For some of us, discovering that Pluto isn’t a proper planet after all means a change of world-view as traumatic as Galileo’s suggestion that it might be just about possible the sun wasn’t going around the Earth.

The process of redefinition has also brought into the open the process whereby new celestial bodies are named. In 1930 astronomers still followed the ancient tradition of calling planets after the Roman gods, and hence gave Pluto the name of the ruler of the underworld (and not that of Walt Disney’s cartoon dog, who first appeared in the same year as the planet).

Unfortunately, improved detection technologies have meant that virtually all names from classical mythology have now been used. The discoverers of recent asteroids have been forced to turn to other sources for their names – as a brief glance at 17059 Elvis and 9007 James Bond demonstrates.

The conventions for naming planets are more stringent – which is why, sadly, the name ‘Xena’ is unlikely to stick. The IAU’s specifications require such bodies to be named objects after creation deities or underworld spirits, hence the names given to some of the other bodies considered for ‘dwarf planet’ status.

90377 Sedna, for instance, is named after an Inuit sea-goddess (who is both), while 50000 Quaoar’s name comes from that of the creator in the Native American Tongva tribe’s myth system.

All of which raises the possibility of a devout astronomer – or perhaps more interestingly a clear-thinking atheist – naming a future planetary discovery after the Christian God, and thereby relegating that deity to just another upstart competing with the Roman pantheon.

Still, there’s already an asteroid named 1930 Lucifer – and Satan, after all, might qualify as an ‘underworld spirit’. A planet named Jehovah could still prove to be the more palatable option.

Useful Links
International Astronomical Union
Facts about Pluto
List of names of minor planets
Astrology and the new planets

I'll carry on flagging up further columns here, unless it starts annoying people.

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