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Previous Next Up Topic Cosmology / Alternative Cosmology / New planet classification system proposal (5752 hits)
By David Russell Date 2013-08-07 11:39
I decided to take a stab at the issue of how planets are classified.  I was originally good with the IAU demoting Pluto out of planet status, but after looking over the data for all these objects I came up with the proposal in the paper I have linked to.

http://arxiv.org/pdf/1308.0616.pdf

I thought you guys might enjoy reading it. 

Dave
By Mike Petersen Date 2013-08-09 10:33
Dave,

Unfortunately your system will never be adopted.  It makes way too much sense.

- Mike
By David Russell Date 2013-08-09 16:40
Thanks Mike! The paper is currently under review at a journal.  I'll let you know what kind of feedback I get from the reviewers. I did not have an issue with Pluto being demoted from planet status, but recently I looked closely at the actual data and the issue with all these 2-10km rocks orbiting the Jovian planets being called "moons", I came to the idea presented in the paper.  I think it is a big improvement over the current system but I guess I would say that since I wrote a paper about it.
By Jade Annand Date 2013-08-15 02:41
I do like the point that, generally speaking, a dwarf X is still an X.

I also like the classification of moons as planets around planets, even though Mars' complement of moons technically goes down to zero with that revision.

I think it's unlikely to be adopted, since it's not just inertia but everyone who had a pet alternate scheme in their head would want to weigh in if the idea got enough visibility. That's okay, though, I guess, isn't it? :)
By David Russell Date 2013-08-16 00:32
Thanks Ritchie. 

Regarding "dwarf x is still an x":  It relates to the core idea that I think is missing in the IAU system.  Simple definitions are used for a major class of objects and then those classes can be broken into specific types.   I used the example of galaxies in the paper - a galaxy is a gravitationally bound rotating collection of gas, dust, stars, star clusters and so on.  Then galaxies are broken into types but each of the types is still considered a galaxy. 

I'm proposing something similar for planets.  The simple definition is an object in primary orbit around the Sun with enough mass to attain a near-spherical shape.  The objects meeting this criteria are of 4 types:  Terrestrial and Jovian planets.  Then the Kuiper belt and more distant icy bodies.  Then the rockier bodies of the asteroid belt - for which Ceres has the largest radius and mass.  The different types all had different regions of formation within the Solar System which explains why the objects of each type have common physical and to some extent dynamical characteristics. 

Regarding the moons.  While Mars would have zero "moons" in my proposal.  It would have two "satellites" - where a satellite is an object in orbit around a planet that is not massive enough to attain a spherical shape and therefore would not be considered a planet if in its own orbit around the Sun.   Moons are simply planets orbiting larger planets in my proposal.  I think it is a simple solution to the ridiculous number of tiny objects being called "moons" that are in orbit around the Jovian planets.

As far as whether or not it will be accepted.  I intend to push the proposal.  First I'm hoping to get it published in a journal.  It is currently under review.  Once I get it published I will e-mail several researchers that I know were unhappy with the IAU resolutions and see if I can generate some support from them.  As far as inertia and other individuals pet schemes - I'm will to support other proposals, so if someone has ideas for improving my proposal I'm good with that. 

A few comments I've already heard or read.

One person wrote me and pointed out that the original idea of the IAU was to limit the number of planets.   While that probably was a factor, I think the system I've proposed handles that well because three of the four classes are completely surveyed and have only 4 planets each.  So the largest planets are in the Jovian and then Terrestrial planet classes respectively, but it is arbitrary to apply this "orbital clearing" criteria.  It is very easy to apply the physical criteria of the mass needed to attain a round shape.  And the IAU dwarf planets meet that criteria. 

Another point has been made that my system does not significantly address the exoplanets - but I do address my thoughts on that in the paper.  Here is an additional thought on exoplanets I did not bring up in the paper:  Exoplanets are found orbiting other stars.  In other words they are part of other solar systems.  I would rather see scientists - when more data - is achieved classify different types of solar systems based upon the nature of the planets orbiting stars.  I'm sure there are patterns - some solar systems are similar to ours but others are very different.  Solar systems similar to ours should at a minimum have likely terrestrial and jovian planets.

What I would also say is that I did not come into this analysis with the intention to restore Pluto as a planet. I was perfectly happy to have Pluto not be a planet.  But when I started looking at the radii and masses of different objects in the Solar System - the proposal in the paper is what I developed as an idea.  And I really like the way I was able to connect the planet definition with the moon definition.
By Mike Petersen Date 2013-08-19 18:14
Dave,

Here's a suggestion.  Why not send your paper to Phil Plait?  You know, the Bad Astronomer.

Just a thought...

Mike
By nickoftime Date 2014-02-05 20:23
Aha, this was in the media in the UK, I wondered if it was the same David Russell...
Previous Next Up Topic Cosmology / Alternative Cosmology / New planet classification system proposal (5752 hits)

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