How many planets?

[Tigger]

Agafaster wrote:

I reckon on the Earth and Moon being a double planet - ok, it fails the barycentre test, but my opinion is based on the sheer size of our moon, and relative to the earth too. no where else has a moon this big in relation to the primary body.

Charon (Pluto's moon) is significantly bigger in proportion to Pluto.  
    -Tig

[metalman]

Vincent wrote:

Cymric wrote:
being used to the familiar chant Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus-Neptune-Pluto

I thought it was:

Mercury-Venus-Earth-Mars-Jupiter-Saturn-Uranus*snigger*-Neptune-Pluto

:-D

Well since they got rid a planet, can't they rename "URANUS" to eleminate those tasteless jokes about the name.

something like .....
"Urectum"  or "Uhemroid" instead :lol:


Uranus from Greek Mythology: The earliest supreme god, a personification of the sky, who was the son and consort of Gaea (Earth) and the father of the Cyclopes and Titans, who was castrated and dethroned by his youngest son, Cronus, at the instigation of Gaea.

[metalman]

blobrana wrote:
Woohoo!
Astronomers have approved the  historic new planet definition  guidelines today,  and  downsizing Earth's neighbourhood from nine principal heavenly bodies to eight by demoting Pluto.

Pluto searching the "Help Wanted"!
Pluto Gets Downsized

 :lol:

[Karlos]

Surely Pluto ought to be right at home in the planetory "Mickey Mouse" category :-)



*fetches coat*

[Vincent]

metalman wrote:
Well since they got rid a planet, can't they rename "URANUS" to eleminate those tasteless jokes about the name.

something like .....
"Urectum"  or "Uhemroid" instead :lol:

Urectum was used in an episode of Futurama.  The one with the garbage asteroid colliding with earth.

Great series that :lol:

@Karlos
Hmmm, starting to post some groaners again eh? ;-)

[Karlos]

Vincent wrote:

@Karlos
Hmmm, starting to post some groaners again eh? ;-)

Moi?

*blink*

[Karlos]

Agafaster wrote:

There is a problem with the definition: 'must have cleared its orbital neighbourhood of other objects' this is done by either swallowing up these objects, or ejecting to another part of the solar system - this falls down when we consider that the earth, mars and indeed Jupiter have objects in their Trojan positions... ie: around the L4 and L5 Lagrange Points. does this now mean these 3 are not planets ?!

Yeah, Jupiter's trojan clusters aren't exactly small either.

[metalman]

Vincent wrote:

Urectum was used in an episode of Futurama.  The one with the garbage asteroid colliding with earth.

Great series that :lol:

Missed that episode  :-(

Agree, great series

[Vincent]

metalman wrote:
Missed that episode  :-(

Shame, you've missed out on seeing Prof Farnsworths' Smelloscope...

*cue jokes about Uranus*

[Dandy]

metalman wrote:
...
Well since they got rid a planet, can't they rename "URANUS" to eleminate those tasteless jokes about the name.

something like .....
"Urectum"  or "Uhemroid" instead :lol:
...

You're talking about Ur-Anus, aren't you?

[Dandy]

cecilia wrote:
...
Pluto is now a "dwarf planet"

But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
 :-?  :-?  :-?

[Tigger]

Dandy wrote:

cecilia wrote:
...
Pluto is now a "dwarf planet"

But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
 :-?  :-?  :-?

Actually we have four dwarf planets, though that number will grow significantly in the future.  At present we have Ceres, Pluto, Charon and Xena, though Xena is not the actual name for the 4th dwarf planet, just a nickname, its actual name will be picked from a list submitted by its submitter next year sometime.
     -Tig

[cecilia]

Dandy wrote:

cecilia wrote:
...
Pluto is now a "dwarf planet"

But isn't a "dwarf planet" still a planet?
So I'd say we now have 12 planets, with three of them beeing "dwarf planets"...
 :-?  :-?  :-?

no, a "dwarf planet" is a new designation.

(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) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

It may be similar to a planet, but at least some scientists see a need for a more specific definition. I think there's going to be more discussion about it (we ARE talking about scientists, after all), but that's the way things stand now.

[blobrana]

Hum,
similar to `minor planets` (which now has been outlawed)...

i personally don't like the name `Dwarf planet` so i just use the terms `Asteroids` which  is probably still OK, and `Kuiper belt objects` to describe the 200+  dwarf planets in the distant parts of our system.

[cecilia]

there's always "plutonian objects"
 :-D

[metalman]

blobrana wrote:
Hum,
similar to `minor planets` (which now has been outlawed)...

i personally don't like the name `Dwarf planet` so i just use the terms `Asteroids` which  is probably still OK, and `Kuiper belt objects` to describe the 200+  dwarf planets in the distant parts of our system.

Possible definitions:
midget planets - small but spherically proportioned
dwarf planets - small and irregularly shaped
minor planets - infant or  juvenile, not reached the age of consent
 Or maybe not  :lol: