World's astronomers meet in Prague for talks on Big Bang, tiny bodies and Pluto

The world's astronomers began gathering in Prague on Monday for a summit which could resolve - among other things - whether Pluto is a planet or simply a big rock floating on the outer edges of the solar system. The Pluto issue is just one of hundreds of topics up for debate over the next 12 days, as the International Astronomical Union holds its first General Assembly meeting in Prague for 39 years.

Astronomers from all over the world began meeting at Prague's Congress Centre on Monday for talks on a vast and bewildering array of topics. Here's just a sample of the lectures and debates on offer on Day One: The Tully-Fisher Relation as a Function of Redshift, The Relation between Galaxy Properties and their Dark Matter Halo and Age-Metallicity Relation in Dwarfs.

But not surprisingly it's the fate of Pluto which has captured the imagination of the media. For years scientists have been arguing whether Pluto, which was first spotted in 1930, is really a planet or just a rather large asteroid. It may lose its status if delegates agree on the exact definition of a planet, something that has eluded astronomers for some time. Jiri Grygar is one of the Czech Republic's leading astronomers.

Jiri Grygar

"Pluto was discovered relatively early, in 1930. But now, in the same territory of the solar system, we already know more than 1,000 bodies, and it's only a matter of time before we will have even more. Of course, because of historical tradition, there are very different opinions about what should be done about Pluto and the other bodies in this territory. And moreover, eleven years ago, the first extra-solar planets - planets that belong to other stars - were discovered, and now we have almost 200 such bodies in our catalogue. So, the Pluto affair is actually a small, tiny part of a more complex problem - the definition of a planet in the universe."

Re-defining Pluto is fairly far down the agenda of the Prague conference, with the origins of the Big Bang and exploration of tiny bodies such as meteors and comets taking precedence. But if Pluto is relegated to the lower league of celestial bodies, that will entail rewriting tens of thousands of schoolbooks and encyclopaedias. Jiri Grygar, however, says rewriting books is part of scientific development.

"That's the normal process of science. I think we have to rewrite our textbooks practically every day, because the discoveries in all kinds of natural sciences are completely rewriting the presence of knowledge. This is the process of science. It's just normal."

Some parts of the General Assembly meeting will be open to the public, and there's even a special daily newspaper to keep space fans up to speed with the discussions inside the Congress Centre. A fitting treatment for a meeting being held in a city at the forefront of astronomical research since the Middle Ages.