Topic: =/\= this just in. pluto IS bigger than eris!

[stoneyface]

or at least the same size. a new observation and calculation of eris' size was determined when it passed in front of a star and three different telescopes were able to mark the occasion by watching it and then calculating its diameter.

article here: http://news.discovery.com/space/pluto-might-be-bigger-but-eris-is-more-massive.html

[stoneyface]

for the record...

i am and was against the demotion of pluto's status.

[ShadowDiver]

here,here..

I agree wholeheartedly....

how can they say "pluto in just a moon.. after all these years teaching us it's a planet!!
what else are they going to rewrite...

[Nemesis]

The whole "Pluto is no longer a planet" issue has been blown out of proportion.

Pluto is part of what has now been recognized as a class of bodies namely "Dwarf Planets".  Just as Jupiter is part of the class of bodies known as "Gas Giant Planets".  Each is a planet of its own respective planet type.

On the other hand given the theories of the origin of Pluto as a moon of Neptune it either shouldn't be classified as a planet at all or our Moon aka Luna should also be considered to be a planet as should other major moons of the system. 

[Tus-XC]

Wrong Nem, this is why (from the IAU):

(1) A "planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".

Dwarf planet is another catagory, its not a sub catagory of planets (such as gas giants), but a sub catagory of things that make up a solar system.  Also the definition precludes moons from ever being a dwarf planet.

While agree mostly w/ the defintion, i believe that pluto should have been grandfathered in to prevent arguements

[Nemesis]

Wrong Nem, this is why (from the IAU):

(1) A "planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".

Dwarf planet is another catagory, its not a sub catagory of planets (such as gas giants), but a sub catagory of things that make up a solar system.  Also the definition precludes moons from ever being a dwarf planet.

I will bow to the authority of the IAU.

Pluto would seem to fail the definition by the origin as a moon of Neptune.  Though the definition doesn't specifically require independent origin just independent orbit. 

The definition also doesn't allow for "binary planets" of approximately the same size.  By definition they would not have "cleared their orbit" due to the existence of the companion and neither orbits the other as the center point they both orbited would not be in either body..

While agree mostly w/ the defintion, i believe that pluto should have been grandfathered in to prevent arguements

Since we are working with scientific definitions I'd avoid the grandfathering.  For non scientific purposes ok but for science no. 

[Tus-XC]

I would be curious about a binary planet system to see if how they would explain it.  It could be that they would be just another class of 'planets' that have cleared their orbits - for example  you would treat the system as a clearing the orbit, and then the planets individually for the remaining defintions.