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What's in a name?

Last Updated on Sunday, 01 December 2013 20:49
Published on Thursday, 03 August 2006 00:00
pluto.jpgAstronomers are wrestling with a definition of 'planet'.  Professor Iwan Williams FRAS is one of a seven person committee set up by the International Astronomical Union (IAU)  to define just what constitutes a planet.

They have just concluded two years of work defining the difference between "planets" and the smaller "solar system bodies" such as comets and asteroids. If the definition is approved on 24 August 2006 at the IAU General Assembly in Prague, our Solar System will include 12 planets, with more to come: eight classical planets that dominate the system, three planets in a new and growing category of "plutons" - Pluto-like objects - and Ceres. Pluto remains a planet and is the prototype for the new category of "plutons."

Unless Pluto continues to be classified as a planet it will be difficult to deny the claim of a new body, provisionally named Xena, which has a diameter  70 miles greater than Pluto' well as the other candidates Ceres and Charon, and no doubt others yet to be revealed as more powerful telescopes probe the solar system. 

The possibility that Pluto might be demoted has created  huge media interest not least since it would require everyone to unlearn what they were taught at school! On the other hand it will be harder to remember the positions of 12 planets without a catchy mnemonic ( The 'Times' suggestion was '“Most Victorian Euphoniums Make Cats Jump Suddenly Unless Neighbours Play Calming Xylophones“ but one reader, taking a dig at astronomers, suggested “Many Very Eminent Minds Considered Jokers Since Unveiling New Planet Called Xena.”  )

If the decision is taken to remove its planetary status from Pluto it will be hard on Venetia Phair (nee Burney), an 87-year-old retired teacher in Epsom, England ... and the only person alive to have named one of our planets: she came up with the suggestion when she was an 11-year-old schoolgirl in Oxford. Her grandfather, Falconer Madan, formerly of the Bodleian Library, impressed by Venetia's suggestion, dropped by the house of Herbert Hall Turner, a friend of his and a Professor of Astronomy at Oxford. Ironically, Turner missed Madan because he was at a meeting of the Royal Astronomical Society, of which he was Foreign Secretary.

When Turner finally heard the suggestion from Madan, he sent a telegram to the Lowell Observatory in Flagstaff, Ariz., where Clyde Tombaugh had discovered the planet. On May 1, 1930, the name Pluto was formally adopted, not only because it was one of the few notable names from classical mythology that had yet to be used but also because the first two letters were the initials of the late Percival Lowell -- after whom the Lowell Observatory was named, and who, along with William Pickering, had predicted the existence of a planet outside Neptune's orbit.

In the following year Tombaugh was awarded the Society's Jackson Gwilt Medal.

Ceres, as another Society award winner, Dr Brian Marsden, has noted has had a chequered history...

'The number of planets has been reduced before. The ancients recognised seven - and in some languages these are still equated with the days of week. After the Copernican revolution the objects associated with Sunday and Monday were dropped and the earth added, so the total became six. William Herschel's discovery of Uranus restored the count to seven. The addition of the four tiny bodies Ceres, Pallas, Juno and Vesta early in the 19th century raised it to 11. Most astronomy books were still counting 11 planets four decades later. Although the discovery of Neptune provided a significant addition, the avalanche of discoveries of more and more small bodies between Mars and Jupiter made it essential to deal with them in a different way. The Royal Astronomical Society recatalogued Ceres as Minor Planet No 1, and the then latest discovery of Thalia was No 23. The minor planets, which are also called asteroids or planetoids, have now been catalogued up to No 134,339'