New Planets definition

Blinkz

Blinkz

Blinkz

Soldato
Joined
18 Oct 2002
Posts
3,184
Location
Frimley, Surrey or 38,000ft
I've been reading about the meeting that has been going on in Prague of the International Astronomical Union (IAU). They are discussing on changing the definition of what makes a Planet and this will most likely affect how we classify our Solar System, mainly Pluto.

The new definition thats being proposed is based on mavity, which makes sense. Link here about whats happening http://news.bbc.co.uk/1/hi/sci/tech/4795755.stm
 
I heard this on the radio earlier.interesting.

Anyway I had a thought, what if earth didn't have a moon, what would be the effects? would we just have high/low tide, or would it just stay at a constant level all the time? are there any other effects that wouldn't be there, should there be no moon?
 
If earth had no moon we wouldn't be here.

I forget the detailed reasons why, but it has something to do with keeping the planet on it's axis.

It was on Horizon a while back
 
AS_Platinum said:
I heard this on the radio earlier.interesting.

Anyway I had a thought, what if earth didn't have a moon, what would be the effects? would we just have high/low tide, or would it just stay at a constant level all the time? are there any other effects that wouldn't be there, should there be no moon?
Click to expand...

the world would end apparently.
 
I still think it should be based on mass and circularity of orbit. Pluto shouldn't be a defined as a planet and should be revealed for what it is, a large comet.
 
Surely anything that orbits the sun should be classed as a planet regardless of size/density or mavity, and anything that orbits a planet should be called a moon.

Obviously there are certain bodies that pass through our solar system on what is an orbit, but to be classed as a planet it should remain within the definition of our solar system.

EDIT: On a side note i saw on the news this morning when i got in from work (06:30) something about 2 new planets being discovered....maybe! Any seen this yet or was i just over tired? :)
 
Last edited:
MNuTz said:
Surely anything that orbits the sun should be classed as a planet regardless of size/density or mavity, and anything that orbits a planet should be called a moon.
Click to expand...

So every hydrogen atom should be considered a planet?
 
MNuTz said:
Surely anything that orbits the sun should be classed as a planet regardless of size/density or mavity,
Click to expand...
We'd end up with milllions upon millions of planets by that definition.
 
A Satellite technically. But in terms of a circular orbit, Pluto should definitely not be considered. It is more a rogue object from the kuiper belt pulled in by the sun. I think any of these objects past the gas giants should not be included.
 
Rilot said:
So every hydrogen atom should be considered a planet?
Click to expand...

now your just being silly. :)

If it doesnt fit into one of the already pre-defined categories, orbits the sun without leaving the solar system then it should be defined as a planet!

However, im sure that some bodies could be classed as one or another, im sure these bodies will cause an endless point of arguement for astonomers.
 
This is has been the problem for so many years! So many different opinions on what a planet should be!! I personally thing that Pluto should not be a planet for the facts that have already been mentioned, its werid orbit etc. Its a tough subject to try and finalise a definitive measure of what makes a planet!
 
On radio 4 i heard that the new deffinition was anything over a 500 Mile radius and orbits the sun.

That made 2 extra planets in our solar system ( No idea what they are im a bit out of touch and technically booted out Pluto, but they are keeping it for historical reasons.
 
MNuTz said:
Surely anything that orbits the sun should be classed as a planet regardless of size/density or mavity, and anything that orbits a planet should be called a moon.

Obviously there are certain bodies that pass through our solar system on what is an orbit, but to be classed as a planet it should remain within the definition of our solar system.

EDIT: On a side note i saw on the news this morning when i got in from work (06:30) something about 2 new planets being discovered....maybe! Any seen this yet or was i just over tired? :)
Click to expand...
The problem with that is that the definition of our solar system is arrived at due to the area occupied by what are currently thought of as its orbiting planets.

For example, by your definition, if Earth were moved outside of the current solar system, but yet retained all its other physical properties - it would cease to be a planet.

Also, under your definition there would be millions of planets in the solar system, as every orbiting meteor, meteorite, even dust particle!! Also, every satellite, space station, etc would become a moon (and presumably the space shuttle would gain temporary moon status whilst in orbit!).
 
j00ni said:
The problem with that is that the definition of our solar system is arrived at due to the area occupied by what are currently thought of as its orbiting planets.

For example, by your definition, if Earth were moved outside of the current solar system, but yet retained all its other physical properties - it would cease to be a planet.

Also, under your definition there would be millions of planets in the solar system, as every orbiting meteor, meteorite, even dust particle!! Also, every satellite, space station, etc would become a moon (and presumably the space shuttle would gain temporary moon status whilst in orbit!).
Click to expand...

If your read above you'll see Rilot already brought this to my tired and exhausted attention (been up 20 hours now and my brain isnt working properly.) :D
 
Last edited:
With all due respect, MNutz, that wouldn't work. Any new object that was discovered, if it did not fall into what you call 'pre-defined categories' it would become a planet. Thus we could have a new type of object, potentially smaller than many other objects that could be called simply 'space dust' (:p) and would have to call it a planet.

There is an excellent discussion of the problem in defining 'planet' here ( http://www.gps.caltech.edu/~mbrown/whatsaplanet/ ) from Mike Brown (of the team who discovered 2003UB313). I would second his conclusion; scientifically it at least means we have a definition of planet, albeit with 53 planets and counting. The bureaucratic attachment however is bizarre.
 
Im not sure of the idea of "plutons" tbh. They should either be planets or not, and IMO they should not be planets. We should have 8 planets, and the others should simply be called Kuiper belt objects. Even with the new deffinition we are likely to discover yet more "plutons" out there, which is going to get might confusing for school children in say 50 years. :)
 
messiah khan said:
Im not sure of the idea of "plutons" tbh. They should either be planets or not, and IMO they should not be planets. We should have 8 planets, and the others should simply be called Kuiper belt objects. Even with the new deffinition we are likely to discover yet more "plutons" out there, which is going to get might confusing for school children in say 50 years. :)
Click to expand...
There's allready a few objects known that will once their details are firmed up will be added to the pluton catorgory.
 
Last edited:
I think one of the problems here is we are being a little to focused on the Solar system, I get the feeling from reading other sources that the reclassification has a much to do with what might be orbitting other stars and how to classify them.
 
You must log in or register to reply here.
Back
Top Bottom