IAU Resolution on the definition of "planet"

[Rick]

The Final IAU Resolution on the definition of "planet" ready for voting

It's all got a bit more complicated, and somewhat subjective, starting thus:

(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.

Full text: http://www.iau2006.org/mirror/www.iau.org/iau0602/index.html

I wonder where the votes will go...

[Tony G]

Looks like I won't get to see 9 planets then.

http://www.chron.com/disp/story.mpl/ap/world/4138544.html

Tony G

[Rick]

The IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as 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.

This means that the Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" was also decided. It was agreed that "planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years. Currently a dozen candidate "dwarf planets" are listed on IAU's "dwarf planet" watchlist, which keeps changing as new objects are found and the physics of the existing candidates becomes better known.

The "dwarf planet" Pluto is recognised as an important proto-type of a new class of trans-Neptunian objects. The IAU will set up a process to name these objects.

See: http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html

[Rick]

Pluto vote 'hijacked' in revolt

A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet.

On Thursday, experts approved a definition of a planet that demoted Pluto to a lesser category of object.

But the lead scientist on Nasa's robotic mission to Pluto has lambasted the ruling, calling it "embarrassing".

And the chair of the committee set up to oversee agreement on a definition implied that the vote had effectively been "hijacked".

More: http://news.bbc.co.uk/1/hi/sci/tech/5283956.stm

[Rick]

No comment: http://www.webbedcomics.com/in.php?id=160

[mickw]

Pluto's years-long identity crisis just got more complex today.

The International Astronomical Union has decided on the term "plutoid" as a name for Pluto and other objects that just two years ago were redefined as "dwarf planets."

The decision is unlikely to stem ongoing controversy and confusion, astronomers say.

Sidestepping concerns of many astronomers worldwide, the IAU's decision, at a meeting of its Executive Committee in Oslo, comes almost two years after it stripped Pluto of its planethood and introduced the term "dwarf planets" for Pluto and other small round objects that often travel highly elliptical paths around the sun in the far reaches of the solar system

More:   http://www.space.com/scienceastronomy/080611-plutoid-planets.html

I reckon someone at the IAU needs a kick in the Plutoids 

[Rick]

The International Astronomical Union (IAU) has awarded poor old Pluto a consolation prize following its controversial demotion from the league of planets - other similar dwarf planets will henceforth be called "plutoids".

More: http://www.theregister.co.uk/2008/06/12/plutoids/

...and from the BBC:

"Plutoid" is the word of the moment for astronomers.

It is the new classification that has been sanctioned for the object that was formerly known as the "ninth planet".

It is nearly two years since the International Astronomical Union (IAU) stripped Pluto of its former status as a "proper" planet.

More: http://news.bbc.co.uk/2/hi/science/nature/7449735.stm

[Mike]

WHY?!

[Rick]

Why not?

[mickw]

Suppose we're lucky Pluto wasn't named Haemorr 

[Fay]

I had to think about that one for a while mick!               

[Rick]

Mitch Benn puts it in song...

https://www.youtube.com/watch?v=io66MHY5M_c