Talk about the re-classification of Pluto from a planet to a new type of celestial body (first dwarf planet, then plutoid) has died down of late. But according to this article from the Telegraph, several “leading astronomers”, including Dr. David Morrison from NASA, believe that Pluto deserves to retain its planetary status.

They claim that the revised definitions are confusing and will mean that newly discovered planets in solar systems outside our own can no longer be described as such.

…

Dr David Morrison, director of the NASA Lunar Science Institute in California, said: “It has never before been necessary for any organisation to define a word that has been in common every day use so I see no reason why it was necessary on this occasion.

“Astronomers use adjectives such as giant and dwarf to describe different subclasses of objects like planets, stars and galaxies, so why could Pluto not remain as a dwarf planet just as Jupiter is a giant planet.

“Also, around 90 per cent of the planets we know now are outside our solar system, but under the International Astronomical Union’s definition, they cannot be classed as planets.”

Scientific terminology has to be precisely defined on a regular basis. In fact, without a rigid definition, scientific terminology becomes relatively meaningless. Though it might seem unfair to Pluto’s fans, it is not within the purview of science to make exceptions in classification out of sentimental value. The IAU came up with a more precise definition of “planet”, and Pluto didn’t happen to belong in that group. Case closed. This doesn’t mean that Pluto will vanish from our solar system, or that we can’t still discover “plutoids” in other solar systems. This in no way quantitatively changes the observations being made, or the science being done — it only gives scientists a more precise tool with which they can classify celestial bodies.

Mark Sykes, from the Planetary Science Institute will argue that roundness should be the only category that is applied.

This, he says, will lead to the number of planets in our own solar system increasing to 12.

Why would it be any more desirable for our solar system to have twelve, rather than eight, planets? It will not change the physical characteristics of the objects, the potential for finding life, or increase the chance that we can one day inhabit them. All we are doing is shifting from one arbitrary definition (all definitions are arbitrary, really) to another more useful/precise definition. The idea that planets should be categorized based on their “roundness” just sounds like a vague criterion that will serve little scientific purpose other than to have Pluto remain classified as a planet.

Dr Neil deGrasse Tyson, from the American Museum of Natural History, will argue that Pluto does not deserve to be a planet.

There might be a good reason for why Pluto should remain classified as a planet, but this article doesn’t mention any of them. It seems that the opposition to Pluto’s plutoid classification is from a few holdout astronomers who are opposed to change for sentimental reasons. Science is not about maintaining the status quo; it’s about explaining the universe, and sometimes we have to change our criteria for classification in order to better facilitate that purpose. If you’re opposed to change, then science probably isn’t the right field for you.

—

• Telegraph.co.uk: Pluto should get back planet status, say astronomers