The greatest astronomers in the world are discussing whether Pluto should be declassified as a planet.
Astronomers from around the world have gathered to tackle a question that could reshape our understanding of the solar system: should Pluto remain a planet?
Delegates attending the general assembly of the International Astronomical Union are divided over how a planet should be defined, and whether Pluto, the smallest and most distant of the traditional nine planets, meets that definition.
The world’s leading astronomers have an important question to settle: the status of our smallest planet, Pluto.
For more than 75 years, Pluto has been recognised as the solar system’s ninth planet. Advances in astronomical research have cast doubt on that classification. Scientists are now debating what characteristics an object must possess to be considered a planet.
With a diameter of just 2,500 kilometres, Pluto is small by planetary standards. When it was discovered in 1930, astronomers believed it was much larger than it actually is. Subsequent observations have revealed that Pluto is smaller than several objects that have since been identified in the outer reaches of the solar system.
David Moore, chairman of Astronomy Ireland, explains how the debate intensified after the discovery of an object beyond Neptune that is larger than Pluto. Astronomers expect many more such discoveries, raising questions about how these bodies should be classified. There could be hundreds of objects larger than Pluto. If Pluto retains its status as a planet, hundreds more planets may have to be recognised. If it does not, then textbooks, classroom charts and our understanding of the Solar System will need to be revised.
An RTÉ News report broadcast on 15 August 2006. The reporter is Anna Murphy.