Chatroom
 

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Bad Astronomy and Universe Today Forum > Science and Space > Astronomy
Register FAQ Members List Calendar Mark Forums Read

   

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 13-October-2006, 09:01 AM
kheider's Avatar
kheider kheider is offline
Junior Member
 
Join Date: Aug 2006
Location: Sacramento, CA
Posts: 42
Question Is 1 Ceres still an Asteroid? (Wiki & IAU)

I had assumed that 1 Ceres was still considered an Asteroid since it orbits in the asteroid belt and has the same origin as the other asteroids.

But I noticed that on wikipedia they say: "Ceres is a 'dwarf planet', and may no longer be classified as an asteroid."

Wiki sites IAU comments at http://www.iau2006.org/mirror/www.ia...0603_Q_A2.html that say:
-------------
Q: What is Ceres?

A: Ceres is (or now we can say it was) the largest asteroid, about 1000 km across, orbiting in the asteroid belt between Mars and Jupiter. Ceres now qualifies as a dwarf planet because it is now known to be large enough (massive enough) to have self-gravity pulling itself into a nearly round shape. [Published reference for shape of Ceres: P. Thomas et al. (2005), Nature 437, 224-227. Dr. Peter Thomas is at Cornell University.] Ceres orbits within the asteroid belt and is an example of a case of an object that does not orbit in a clear path. There are many other asteroids that can cross the orbital path of Ceres.


Q: Didn’t Ceres used to be called an asteroid or minor planet?

A: Historically, Ceres was called a “planet” when it was first discovered (in 1801) orbiting in what is known as the asteroid belt between Mars and Jupiter. Because 19 th century astronomers could not resolve the size and shape of Ceres, and because numerous other bodies were discovered in the same region, Ceres lost its planetary status. For more than a century, Ceres has been referred to as an asteroid or minor planet.
-------------

Is it NOT correct to say:

Ceres is still the largest asteroid even though Ceres is also a 'dwarf planet'. Pluto is a Kuiper Belt Object (KBO) even though it is also a 'dwarf planet'.

???

-- Kevin Heider
Reply With Quote
  #2 (permalink)  
Old 13-October-2006, 09:35 AM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

It IS correct say that. Ceres is still an asteroid (or like the IAU says, a minor planet). Pluto and Eris ARE Kuiper belt objects.

Otherwise the term "dwarf planet" would be contradictory: If they're not members of the belts, then why they're not true planets?

EDIT: Argh, now I read the IAU Q&A... I think it's wrong. "Asteroid" means "minor planet" (despite that Wikipedia claims otherwise). When the Minor Planet Center assigned Pluto a minor planet number, they mentioned that objects can have dual classifications (there are a few asteroid-comets). So Ceres is a minor planet, as is Pluto. Ceres it is a dwarf planet, but it is also an asteroid (unless asteroids = small solar system objects sans comets).
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #3 (permalink)  
Old 13-October-2006, 11:44 AM
Blob's Avatar
Blob Blob is offline
Order of Kilopi
 
Join Date: Sep 2005
Posts: 3,410
Default

Hum,
The term `minor planet` is banned.
All references to it should be removed from the textbooks, public buildings and temples;
The term `small solar system objects` is now preferred.
The term `Asteroid` can be used, but not in public debate or scientific papers - it is best used in pubs for tittle-tattle.

However, Ceres is technically not a small solar system objects because it is a dwarf planet.
__________________
`Irony` actually does mean `metal like`...
Reply With Quote
  #4 (permalink)  
Old 13-October-2006, 12:28 PM
the_shaggy_one's Avatar
the_shaggy_one the_shaggy_one is offline
Established Member
 
Join Date: Jan 2005
Location: Minnesota
Posts: 213
Send a message via AIM to the_shaggy_one Send a message via MSN to the_shaggy_one Send a message via Yahoo to the_shaggy_one
Default

Also, remember that the wikipedia article is the collective opinions of everyone who participated in writing it, not any sort of authority on the nomenclature of the solar system.

As I understand it, asteroid is still a useful descriptor for objects that are part of the asteroid belt and NEAs, as it represents a dynamical grouping of bodies that share similar orbital and physical characteristics. Specific names for different groups exist, such as Atens, TNOs, Jupiter Trojans, Centaurs, etc. so it's probably best to use those descriptors, rather than the catch-all SSSB.

the term 'SSSB' replaces the outdated and confusing term 'minor planet', but does not affect the names for more specific dynamic groups.

Thus, the terms SSSB, dwarf planet, and planet tell us something about how massive the object is, from small irregular bodies, to rounded bodies, to bodies large enough to sweep out the debris of planetary formation. The specific names for dynamical groups tell us where the objects are, and in some cases where they came from or what they're made of. Planets can also form dynamic groups, such as the terrestrial planets and gas giants.

So Ceres is both a dwarf planet and asteroid, and is sometimes even counted as a terrestrial planet. Pluto is a dwarf planet, TNO, KBO, and plutino. Eris is a dwarf planet, TNO, and SDO. Both Pluto and Eris also belong to a new and unnamed group of eccentric, inclined, long-period ice dwarfs. (Wouldn't that be a fun bit of terminology, the 'EILPIDs'!)

To me, this new classification system makes a lot of sense, and avoids being extremely arbitrary. There are going to be borderline cases where it's not exactly clear which groups a body belongs to. I see those are merely opportunities to refine the terminology, and don't see why they should doom the definition as a whole.
__________________
audentes fortuna iuvat
Reply With Quote
  #5 (permalink)  
Old 13-October-2006, 12:35 PM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

Quote:
Originally Posted by Blob View Post
Hum,
The term `minor planet` is banned.
All references to it should be removed from the textbooks, public buildings and temples;
The term `small solar system objects` is now preferred.
The term `Asteroid` can be used, but not in public debate or scientific papers - it is best used in pubs for tittle-tattle.

However, Ceres is technically not a small solar system objects because it is a dwarf planet.
The IAU Small Solar System Body Center, eh?

Since dwarf planets are also minor planets asteroids, the term "asteroid" includes both non-cometary SSSBs and dwarf planets. In other words, asteroids don't form a subset of SSSBs.
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #6 (permalink)  
Old 13-October-2006, 12:54 PM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

Quote:
Originally Posted by the_shaggy_one View Post
Also, remember that the wikipedia article is the collective opinions of everyone who participated in writing it, not any sort of authority on the nomenclature of the solar system.
As a TOP1000 Wikipedia contributor who has focused on asteroids I know that.

I don't count comets as minor planets, nor does the MPC. In a sense it is odd since KBOs are minor planets but comets like Halley which is believed to have originated from there, isn't. Although the term "SSSB" is clumsy, it hopefully makes this more clear.

Quote:
Originally Posted by the_shaggy_one View Post
As I understand it, asteroid is still a useful descriptor for objects that are part of the asteroid belt and NEAs, as it represents a dynamical grouping of bodies that share similar orbital and physical characteristics. Specific names for different groups exist, such as Atens, TNOs, Jupiter Trojans, Centaurs, etc. so it's probably best to use those descriptors, rather than the catch-all SSSB.
Then we agree.

Quote:
Originally Posted by the_shaggy_one View Post
the term 'SSSB' replaces the outdated and confusing term 'minor planet', but does not affect the names for more specific dynamic groups.
Not actually. 'Minor planet' is synonymous to 'asteroid' (or if you don't count TNOs as asteroids, then MP = asteroids + TNOs). I think it's highly unlikely that the term 'minor planet' will be removed from use.

Then why the term "dwarf planet" had to be invented (planetoid, although historically synonymous to asteroids, would have been much better)... To be fair, if Resolution 5B had passed, they would have formed a subset of planets. And it is a nod to Pluto and its kin. Not a planet, but a dwarf planet anyway.

Quote:
Originally Posted by the_shaggy_one View Post
Thus, the terms SSSB, dwarf planet, and planet tell us something about how massive the object is, from small irregular bodies, to rounded bodies, to bodies large enough to sweep out the debris of planetary formation. The specific names for dynamical groups tell us where the objects are, and in some cases where they came from or what they're made of. Planets can also form dynamic groups, such as the terrestrial planets and gas giants.
There's nothing dynamical in terrestrial/gas giant classification. It is based purely on physical properties, but happens to split the groups nicely in dynamical sense in our Solar system since the gas giant's didn't migrate as much as in some planetary systems.

Quote:
Originally Posted by the_shaggy_one View Post
So Ceres is both a dwarf planet and asteroid, and is sometimes even counted as a terrestrial planet. Pluto is a dwarf planet, TNO, KBO, and plutino. Eris is a dwarf planet, TNO, and SDO. Both Pluto and Eris also belong to a new and unnamed group of eccentric, inclined, long-period ice dwarfs. (Wouldn't that be a fun bit of terminology, the 'EILPIDs'!)
Ceres is not a terrestrial planet by any means.

The members in the unnamed group are dwarf planets and are located beyond Neptune. Circular, non-inclined orbits are allowed, so "EILPID" would be a misleading term.

Quote:
Originally Posted by the_shaggy_one View Post
To me, this new classification system makes a lot of sense, and avoids being extremely arbitrary. There are going to be borderline cases where it's not exactly clear which groups a body belongs to. I see those are merely opportunities to refine the terminology, and don't see why they should doom the definition as a whole.
I like the three-tier classification system planet/dwarf planet/SSSB. What I don't like is that the term "asteroid/minor dwarf" isn't a true subset of SSSBs. But I understand it would highly impractical to manage dwarf planets separately.
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #7 (permalink)  
Old 13-October-2006, 02:06 PM
the_shaggy_one's Avatar
the_shaggy_one the_shaggy_one is offline
Established Member
 
Join Date: Jan 2005
Location: Minnesota
Posts: 213
Send a message via AIM to the_shaggy_one Send a message via MSN to the_shaggy_one Send a message via Yahoo to the_shaggy_one
Default

As far as I knew, the new category was for bodies with eccentric inclined orbits with a period >200 years. Did that part of it not make it past the draft resolution?

I kinda liked the word I made up... It wouldn't be any more misleading than many of the other terms used in astronomy, though... There's precedent! XD

Oh, and I know Ceres isn't a traditional terrestrial planet, that's why I said sometimes. so there!
__________________
audentes fortuna iuvat
Reply With Quote
  #8 (permalink)  
Old 13-October-2006, 02:33 PM
Atraveller's Avatar
Atraveller Atraveller is offline
Established Member
 
Join Date: Sep 2006
Location: Living in Paradise
Posts: 234
Default

It does seem that Ceres would be a very interesting destination for an unmanned probe. Do any of the space agencies have plans to send anything to check it out?
__________________
Gone Sailing
Reply With Quote
  #9 (permalink)  
Old 13-October-2006, 02:42 PM
Ilya's Avatar
Ilya Ilya is offline
Order of Kilopi
 
Join Date: Nov 2001
Location: Boston
Posts: 3,480
Default

Quote:
Originally Posted by Atraveller View Post
It does seem that Ceres would be a very interesting destination for an unmanned probe. Do any of the space agencies have plans to send anything to check it out?
Yes. Dawn
__________________
Fiction has to be plausible. Reality is under no such constraint.
Reply With Quote
  #10 (permalink)  
Old 13-October-2006, 02:43 PM
Darrrius Darrrius is offline
Established Member
 
Join Date: Jan 2005
Posts: 174
Default

I believe DAWN will be visiting in a few years time: http://www.dawn-mission.org/mission/index.asp
Reply With Quote
  #11 (permalink)  
Old 13-October-2006, 03:02 PM
Atraveller's Avatar
Atraveller Atraveller is offline
Established Member
 
Join Date: Sep 2006
Location: Living in Paradise
Posts: 234
Default

Quote:
Originally Posted by Ilya View Post
Yes. Dawn
Cool - just have to wait 9 years to see how it works out...

Thanks for the link
__________________
Gone Sailing
Reply With Quote
  #12 (permalink)  
Old 13-October-2006, 03:52 PM
ASEI's Avatar
ASEI ASEI is offline
Established Member
 
Join Date: May 2004
Posts: 1,416
Default

Quote:
Is 1 Ceres still an Asteroid?
Has it started fusioning or something? :-P
Reply With Quote
  #13 (permalink)  
Old 13-October-2006, 04:18 PM
CuddlySkyGazer CuddlySkyGazer is offline
Junior Member
 
Join Date: Aug 2006
Location: London
Posts: 92
Default

Despite the IAU Q&A cited, there is still some dispute as to whether Ceres remains an asteroid or not.

It is definitely a dwarf planet. The question is whether a dwarf planet can simultaneously be an asteroid. Do the definitions overlap?

The definition passed in August divided bodies other than the Sun in our solar system into three - planets, dwarf planets and small solar system bodies (SSSBs). The resolution stated: "All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies"". Note 3 was: "These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies."

OK, if SSSBs only include 'most' of the asteroids, then there must be some asteroids that are not SSSBs. The eight planets were never asteroids, so that only leaves the three dwarf planets as possible asteroids (or TNOs). Hence - is Ceres still an asteroid?
Reply With Quote
  #14 (permalink)  
Old 13-October-2006, 04:55 PM
ASEI's Avatar
ASEI ASEI is offline
Established Member
 
Join Date: May 2004
Posts: 1,416
Default

Is Australia an island, continent, or country?
Reply With Quote
  #15 (permalink)  
Old 13-October-2006, 05:48 PM
kheider's Avatar
kheider kheider is offline
Junior Member
 
Join Date: Aug 2006
Location: Sacramento, CA
Posts: 42
Default

Quote:
Originally Posted by ASEI View Post
Is Australia an island, continent, or country?
For which I ask:

Name the 1st Asteroid discovered? Ceres or Pallas?

Name the largest Asteroid? Ceres or Vesta?

*IF* Ceres is truely no longer an asteroid because it is spherical then those two very basic questions have new answers!

-- Kevin Heider
Reply With Quote
  #16 (permalink)  
Old 13-October-2006, 05:50 PM
Blob's Avatar
Blob Blob is offline
Order of Kilopi
 
Join Date: Sep 2005
Posts: 3,410
Default

Quote:
Originally Posted by CuddlySkyGazer View Post
is Ceres still an asteroid?
Hum,
my take on it is that it is an asteroid. (though the term is now outdated)
But by being classed as a dwarf planet it excludes it from being a SSSB.

(ie, the earth is classed as a planet so it excludes it from being a SSSB)
__________________
`Irony` actually does mean `metal like`...
Reply With Quote
  #17 (permalink)  
Old 13-October-2006, 07:38 PM
kheider's Avatar
kheider kheider is offline
Junior Member
 
Join Date: Aug 2006
Location: Sacramento, CA
Posts: 42
Default

Quote:
Originally Posted by Blob View Post
my take on it is that it is an asteroid.
I agree.

Quote:
Originally Posted by Blob View Post
(though the term is now outdated)
I disagree. The term Asteroids still define non-planets originating from the region of the asteroid belt. The Asteroid Belt and Kuiper Belt do exist.

Quote:
Originally Posted by Blob View Post
But by being classed as a dwarf planet it excludes it from being a SSSB.
I disagree. Then why was Pluto and Eris assigned a Minor Planet (now SSSB) number? I believe that 'dwarf planets' are a subset of SSSBs, and thus will never be major planets.

-- Kevin Heider
Reply With Quote
  #18 (permalink)  
Old 13-October-2006, 07:46 PM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

Dwarf planets are not SSSBs.

After the definitions of a planet (1) and a dwarf planet (2) comes the definition of Small Solar System Body:

Quote:
(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".
(emphasis mine)
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #19 (permalink)  
Old 13-October-2006, 08:08 PM
kheider's Avatar
kheider kheider is offline
Junior Member
 
Join Date: Aug 2006
Location: Sacramento, CA
Posts: 42
Default

Quote:
Originally Posted by Kullat Nunu View Post

Dwarf planets are not SSSBs.

After the definitions of a planet (1) and a dwarf planet (2) comes the definition of Small Solar System Body:

(3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".
But that does not require that 'dwarf planets' be excluded from the list of Minor Planets (SSSBs). Since Pluto and Eris have been assigned SSSB numbers, I think the IAU intends to include 'Dwarf Planets' as SSSBs.

Only Major Planets and satellites will not receive SSSB numbers.

-- Kevin Heider
Reply With Quote
  #20 (permalink)  
Old 13-October-2006, 08:32 PM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

No, that means some minor planets/asteroids are not SSSBs. Pluto and Eris have been assigned minor planet numbers. There's not such thing as "SSSB number" (comets have different designation schemes).

Quote:
3 These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
Like mentioned earlier, it reads most, not all.

Pluto and Eris received minor planet numbers for practical reasons: Ceres already has one and some of the largest numbered TNOs will most likely be reclassified as dwarf planets.
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #21 (permalink)  
Old 13-October-2006, 08:43 PM
Blob's Avatar
Blob Blob is offline
Order of Kilopi
 
Join Date: Sep 2005
Posts: 3,410
Default

Quote:
Originally Posted by kheider View Post
I disagree. Then why was Pluto and Eris assigned a Minor Planet (now SSSB) number? I believe that 'dwarf planets' are a subset of SSSBs, and thus will never be major planets.
Hum,
perhaps...
But its possible that they didn't think of that consequence when they created the new class of Dwarf planet.

Quote:
small solar system body (SSSB) is a term defined in 2006 by the International Astronomical Union to describe solar system objects which are neither planets, nor dwarf planets:

All other objects orbiting the Sun shall be referred to collectively as "Small Solar System Bodies" ... These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.[1]
Therefore it refers to these objects that can be further classified based on their orbit or composition:
* all known minor planets that are not dwarf planets, i.e.:
* the classical asteroids (except the largest one, 1 Ceres);
* the Centaurs and Neptune Trojans;
* the smaller Trans-Neptunian Objects (except dwarf planets such as Pluto and Eris);
* all comets;
http://en.wikipedia.org/wiki/Small_solar_system_body

If the IAU really intended to include 'Dwarf Planets' as SSSBs, then it could be assumed that the definition of planets is a also subgroup of SSSBs.
__________________
`Irony` actually does mean `metal like`...
Reply With Quote
  #22 (permalink)  
Old 13-October-2006, 09:12 PM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

"All other objects..." says rather explicitly that objects excluding planets, dwarf planets, and moons are SSSBs.

Quote:
Originally Posted by kheider
...and thus will never be major planets.
Never say never... If the Resolution 5B had passed, "dwarf planets" and "classical planets" would have formed two categories of objects called "planets". Since it didn't pass, "dwarf planets" are not real planets. That vote was the one which actually demoted Pluto.
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #23 (permalink)  
Old 13-October-2006, 09:31 PM
Macro Mouse's Avatar
Macro Mouse Macro Mouse is offline
Junior Member
 
Join Date: Jan 2004
Location: United States
Posts: 85
Default

Splitting the solar system into three groups (planets, dwarf planets, SSBs)...

Poor Titan.

Honestly what's the need for the term dwarf planet. I think if the definition were just based on orbital characteristics it would make things easier.

Planet=orbits primary body (star, brown dwarf, free floater), and has dynamically cleared its zone.
In our solar system: 4 terrestrial planets, 2 gas giant planets, 2 ice giant planets

Debris=orbits primary body (star, brown dwarf, free floater), and is dynamically insignificant.
In our solar system: an assortment of asteroids, ice dwarfs, and comets

Satellites=orbits secondary body (planets, debris).

So IMO, Ceres is an asteroid...a Main Belt Object to be specific.
__________________
This space is for rent.
Reply With Quote
  #24 (permalink)  
Old 13-October-2006, 09:32 PM
kheider's Avatar
kheider kheider is offline
Junior Member
 
Join Date: Aug 2006
Location: Sacramento, CA
Posts: 42
Default

Quote:
Originally Posted by Kullat Nunu View Post
kheider wrote: ...and thus ('dwarf planets') will never be major planets.

Never say never... If the Resolution 5B had passed, "dwarf planets" and "classical planets" would have formed two categories of objects called "planets". Since it didn't pass, "dwarf planets" are not real planets.
True. But that is why I wrote MAJOR Planet. I left myself wiggle room.

Quote:
Originally Posted by Kullat Nunu View Post
Some minor planets/asteroids are not SSSBs. Pluto and Eris have been assigned minor planet numbers. There's not such thing as "SSSB number" (comets have different designation schemes).
OK. I thought the IAU was replacing all future references to Minor Planets with SSSBs. But you are right active comets do not receive Minor Planet numbers.

So Ceres is a 'dwarf planet', asteroid, 'minor planet', and aka big rock in space.

If the term 'minor planets' is still used that means we still have 136k minor planets instead of 136k SSSBs.

Now I can go play with 1 Ceres at Wiki and get yelled at.

-- Kevin Heider
Reply With Quote
  #25 (permalink)  
Old 14-October-2006, 09:46 AM
agingjb's Avatar
agingjb agingjb is offline
Established Member
 
Join Date: Feb 2005
Location: UK
Posts: 677
Default

I can't see any reason to stop calling Ceres an asteroid. Are they going to renumber all the others now?

I'd agree with those who find the "dwarf planet" class a little odd. There are seven mere satellites larger than most (all?) dwarf planets - known and unknown, and they are all incomparably more interesting.

Why classify by orbit at all? Surely such namings belong to publicity not science.
Reply With Quote
  #26 (permalink)  
Old 14-October-2006, 11:19 AM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

Quote:
Originally Posted by agingjb View Post
I can't see any reason to stop calling Ceres an asteroid. Are they going to renumber all the others now?
Ceres remains an asteroid and other asteroids will not be renumbered (what would be the point with that)? Vesta, Pallas, and Hygiea were potential planets in the original draft resolution so they may get eventually promoted.

Quote:
Originally Posted by agingjb View Post
I'd agree with those who find the "dwarf planet" class a little odd. There are seven mere satellites larger than most (all?) dwarf planets - known and unknown, and they are all incomparably more interesting.

Why classify by orbit at all? Surely such namings belong to publicity not science.
Why not? After all, the term 'planet' refers to a substellar (and sub-brown dwarf) object which orbits a star. So the term is fundamentally related to dynamics.

An example of more "scientific" classification scheme could be a classification based on separate physical and orbital properties (circumstellar planemo ~ 'planet', circumplanetary planemo ~ 'large moon' etc.).
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
  #27 (permalink)  
Old 14-October-2006, 06:46 PM
Kaptain K's Avatar
Kaptain K Kaptain K is offline
Order of Kilopi
 
Join Date: Oct 2001
Location: Elgin, Tx
Posts: 7,674
Default

Quote:
Originally Posted by ASEI View Post
Is Australia an island, continent, or country?
Yes!
__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson
Reply With Quote
  #28 (permalink)  
Old 15-October-2006, 06:58 AM
Superluminal's Avatar
Superluminal Superluminal is offline
Established Member
 
Join Date: Aug 2003
Posts: 1,423
Default

Since everybody is into reclassifying things, why not reclassify Saturn's moon Enceladus a comet nucleus. Some of the pictures of it taken by Cassini, it certainly shows the characteristics of a comet nucleus.

They like to say that if Pluto were discovered today it would never have been considered a planet. Well, if we had no knowledge of Jovian type planets and Jupiter was discovered today, would it be a planet or a failed star?
__________________
I'm not a scientist, but I play one on the internet.
http://www.rrac.org
Reply With Quote
  #29 (permalink)  
Old 15-October-2006, 10:14 AM
Kullat Nunu's Avatar
Kullat Nunu Kullat Nunu is offline
Established Member
 
Join Date: Sep 2003
Location: Earth
Posts: 2,808
Send a message via MSN to Kullat Nunu Send a message via Skype™ to Kullat Nunu
Default

Quote:
Originally Posted by Superluminal View Post
Since everybody is into reclassifying things, why not reclassify Saturn's moon Enceladus a comet nucleus. Some of the pictures of it taken by Cassini, it certainly shows the characteristics of a comet nucleus.
The plumes of Enceladus are most likely generated by internal heat. In comets, the Sun's warmth makes them active. So, it's not a comet nucleus. Even worse, it orbits a planet, which makes it a satellite, no matter how comet-like it would be (c.f. the irregular satellites which may be very comet-like in composition and origin).

Quote:
Originally Posted by Superluminal View Post
They like to say that if Pluto were discovered today it would never have been considered a planet.
They're right.

Quote:
Originally Posted by Superluminal View Post
Well, if we had no knowledge of Jovian type planets and Jupiter was discovered today, would it be a planet or a failed star?
Maybe not a planet but not a failed star, either (Jupiter is not nearly massive enough).
__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT. The time now is 10:44 AM.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2009, Jelsoft Enterprises Ltd.
LinkBacks Enabled by vBSEO 3.0.0
©  2006 Bad Astronomy and Universe Today