16 August 2006

More Planets Rather Than Less?

Following on from Monday's Judgement Day for Pluto the International Astronomical Union (IAU) may have come up with a solution which downgrades Pluto but still recognises it as a planet. The following is based on a report on the BBC website.

The IAU proposal recognises eight classical planets, three planets belonging to a new category called "plutons" (Pluto, its satellite Charon and UB313, aka Xena) and the largest asteroid Ceres. Pluto thus remains a planet, but becomes the basis for a new category. Astronomers gathered at the IAU General Assembly in Prague will vote on the plan next Thursday.

Dr Andrew Coates of the Mullard Space Science Laboratory in Dorking said he thought the plan was "a good compromise". He explained: "It keeps the idea of eight classical planets, while Pluto is allowed to retain its status. But other objects are allowed in, which I suppose makes life more interesting. Something had to be done about the definition.... It does change the textbooks somewhat, but it also demonstrates that this is a vibrant area of research..... The surprise is Ceres, because most people thought of it as an asteroid". (Ceres is the largest object in the asteroid belt between Mars and Jupiter, and like a planet is spherical in shape)

The basis for this re-evaluation is a new scientific definition of a planet which uses gravity as the determining factor. According to this definition, two conditions must be satisfied for an object to qualify as a planet: The object must be in orbit around a star, but must not itself be a star; It must have enough mass for the body's own gravity to pull it into a nearly spherical shape

More objects are likely to be announced as planets in the future. The IAU has a "watchlist" of at least a dozen other potential candidates that could become planets once more is known about their sizes and orbits. These include the distant objects Sedna, Orcus, Quaoar and 2003 EL61 and the asteroids Vesta, Pallas and Hygiea.


Anonymous said...

This is pretty interesting. I too am interested in space, i have always grown up loving it.

jams o donnell said...

Me too Tom ever since I was a small child watchig the moon landings. I was 6 when Armstrong set foot on the Moon. It was one of the highlights of my life when I got to meet him back in 1989

elasticwaistbandlady said...

Personally, I love it that there will finally be a celestial body bearing the name of Xena:Warrior Princess. One can only hope that a Planet Hercules isn't far behind.

jams o donnell said...

Me I want planet Kirk, Plaent Spock, picard, Worf and so on. I hope they keep the name Xena for UB313.. it looks like it has a moon, that has been nicknamed Gabrielle!

elasticwaistbandlady said...

They should shorten it to just Gabriel, to pay tribute to Peter. Latest American survey shows that we know the names of all Seven Dwarfs, but next to none of our 12 Supreme Court Judges. Pop culture knowledge remains the dominant, apparently.

jams o donnell said...

To be honest the UK is not that different. I could name the bridge crews of the Enterprises, but I'm damned if I could name our Law Lords (our equivalent of your supreme court)!