Pluto relegated to the underworld

[mcgillianaire]

The International Astronomical Union has redefined our solar system by declaring Pluto to be a dwarf planet. As a result, there are now only 8 true planets & 3 newly-created dwarf planets.

Read More

Comments

[thangkas.livejournal.com]

There should actually be more "dwarf planets", or they just need to unclassify that and call them planetoids/TNOs as they were before, otherwise the discussion turns to distance from the sun and size/shape. I mean, Ceres? Really? And Charon!?!? That's a satellite of Pluto! So does that mean Pluto is a binary dwarf planet?!

[pappubahry.livejournal.com]

And Charon!?!? That's a satellite of Pluto! So does that mean Pluto is a binary dwarf planet?!
I'm not sure what the current status is, but I think it quite likely that Pluto-Charon will be considered a binary dwarf-planet system. The reason for this is that their common centre of mass is outside both planets (which is because Charon has roughly half the mass of its 'parent planet', unlike all the other moons).

[thangkas.livejournal.com]

Which also points even more so to the impression that it should not be called a planet. Mind you the current definition of planet as it stands now discounts Charon on this basis (as well as many others) as well.

[mcgillianaire.livejournal.com]

What does TNO stand for?

[pappubahry.livejournal.com]

Trans-Neptunian object.

[thangkas.livejournal.com]

Trans Neptunian Object. Another name for KBO (Kuiper Belt Object)

[gpaciga.livejournal.com]

There certaintly will be many more dwarf planets -- there are at least twelve more on a waiting list already. That's why they wanted to make the distinction between the classical planets and the more common dwarfs.