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Glend
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 Posted: Thu Jun 12, 2008 1:23 am Post subject: Pluto, like Eris, is now a "Plutoid" |
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"Here's the official new definition:
" "Plutoids are celestial bodies in orbit around the sun at a distance
greater than that of Neptune that have sufficient mass for their self-
gravity to overcome rigid body forces so that they assume a
hydrostatic equilibrium (near-spherical) shape, and that have not
cleared the neighborhood around their orbit."
"In short: small round things beyond Neptune that orbit the sun and
have lots of rocky neighbors.
"The two known and named plutoids are Pluto and Eris, the IAU stated.
The organization expects more plutoids will be found."
http://news.yahoo.com/s/space/20080611/sc_space/plutonowcalledaplutoid
They also acknowledge that this adds to an ongoing controversy.
I have to wonder if this isn't akin to the "splitting" that many
condemn in biology. We may be stuck with an increasing number of
names, which may be confusing to the public.
On the other hand, it's almost certainly a better name than "dwarf
planet." A "dwarf galaxy" is a small galaxy, yet a "dwarf planet" was
not considered to be a planet.
So on the whole, I myself prefer "plutoid" to "dwarf planet".
Glen Davidson
http://tinyurl.com/2kxyc7 |
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Guest
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| Posted: Fri Jun 13, 2008 12:49 am Post subject: Re: Pluto, like Eris, is now a "Plutoid" |
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On Jun 12, 4:40 pm, Ye Old One <use...@mcsuk.net> wrote:
| Quote: |
3) No asteroid has a moon, Pluto does.
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This is incorrect - dozens of asteroid satellites have been found
since 1993, when the first one, a satellite of (243) Ida, was
discovered.
Reference: http://en.wikipedia.org/wiki/List_of_asteroid_moons |
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Zaius
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| Posted: Fri Jun 13, 2008 2:50 am Post subject: Re: Pluto, like Eris, is now a "Plutoid" |
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On Jun 12, 2:13 pm, Earle Jones <earle.jo...@comcast.net> wrote:
| Quote: |
In article
5ac79a5b-c0d0-4edf-851e-32ea35c5d...@z66g2000hsc.googlegroups.com>,
The Last Conformist <andre...@gmail.com> wrote:
On Jun 12, 3:23 am, Glend <interelectromagne...@yahoo.com> wrote:
[snip]
So on the whole, I myself prefer "plutoid" to "dwarf planet".
Please note that plutoids are a subset of dwarf planets - specifically
those dwarf planets with a semimajor axis greater than Neptune's. This
means that Ceres is a dwarf planet but not a plutoid.
IAU link:
http://www.iau.org/public_press/news/release/iau0804/
*
They took away your Pluto.
Next, they're coming after Uranus.
earle
*
They came first for Pluto, And I didn’t speak up because I wasn’t a |
planetoid;
Then they came for Uranus, And I didn’t speak up because I wasn’t a
gas giant; |
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The Enigmatic One
Guest
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| Posted: Fri Jun 13, 2008 11:00 am Post subject: Re: Pluto, like Eris, is now a "Plutoid" |
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In article <ed52545dgof1778jivhuaretkbboc10cng@4ax.com>,
usenet@mcsuk.net says...
| Quote: |
On Thu, 12 Jun 2008 05:01:17 -0700 (PDT), The Last Conformist
andreasj@gmail.com> enriched this group when s/he wrote:
On Jun 12, 3:23 am, Glend <interelectromagne...@yahoo.com> wrote:
[snip]
So on the whole, I myself prefer "plutoid" to "dwarf planet".
Please note that plutoids are a subset of dwarf planets - specifically
those dwarf planets with a semimajor axis greater than Neptune's. This
means that Ceres is a dwarf planet but not a plutoid.
IAU link:
http://www.iau.org/public_press/news/release/iau0804/
Pluto is the ninth planet of our Solar System. It was discovered by
Clyde W. Tombaugh on February 18th 1930.
That is a FACT of history and there are many of us that are determined
to respect it.
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From your (fucked up) logic, you'd have to agree that Pluto is not the
ninth planet, but rather the tenth. Ceres was recognized as a planet
before Pluto was.
-Tim |
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Ye Old One
Guest
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| Posted: Fri Jun 13, 2008 11:00 am Post subject: Re: Re: Pluto, like Eris, is now a "Plutoid" |
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On Thu, 12 Jun 2008 17:49:10 -0700 (PDT), allisonki@ignmail.com
enriched this group when s/he wrote:
| Quote: |
On Jun 12, 4:40 pm, Ye Old One <use...@mcsuk.net> wrote:
3) No asteroid has a moon, Pluto does.
This is incorrect - dozens of asteroid satellites have been found
since 1993, when the first one, a satellite of (243) Ida, was
discovered.
Reference: http://en.wikipedia.org/wiki/List_of_asteroid_moons
Most of those are, more correctly, double asteroids. Most of the rest |
the "moon" are tiny chips from the main asteroid.
Compare any on the list to the Pluto/Charon system and the difference
is self evident.
--
Bob. |
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Ye Old One
Guest
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| Posted: Fri Jun 13, 2008 11:00 am Post subject: Re: Re: Pluto, like Eris, is now a "Plutoid" |
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On Fri, 13 Jun 2008 07:10:26 +0100, "Mike Dworetsky"
<platinum198@pants.btinternet.com> enriched this group when s/he
wrote:
| Quote: |
"Ye Old One" <usenet@mcsuk.net> wrote in message
news:gc1354td9umu51vk4cludsis3kichev7d3@4ax.com...
On Thu, 12 Jun 2008 18:41:35 +0100, Ernest Major
{$to$}@meden.demon.co.uk> enriched this group when s/he wrote:
In message <m4l254df2uv99nn11iu5562bg13qnknjc4@4ax.com>, Ye Old One
usenet@mcsuk.net> writes
On Thu, 12 Jun 2008 15:18:17 +0100, Ernest Major
{$to$}@meden.demon.co.uk> enriched this group when s/he wrote:
In message <ed52545dgof1778jivhuaretkbboc10cng@4ax.com>, Ye Old One
usenet@mcsuk.net> writes
On Thu, 12 Jun 2008 05:01:17 -0700 (PDT), The Last Conformist
andreasj@gmail.com> enriched this group when s/he wrote:
On Jun 12, 3:23 am, Glend <interelectromagne...@yahoo.com> wrote:
[snip]
So on the whole, I myself prefer "plutoid" to "dwarf planet".
Please note that plutoids are a subset of dwarf planets - specifically
those dwarf planets with a semimajor axis greater than Neptune's. This
means that Ceres is a dwarf planet but not a plutoid.
IAU link:
http://www.iau.org/public_press/news/release/iau0804/
Pluto is the ninth planet of our Solar System. It was discovered by
Clyde W. Tombaugh on February 18th 1930.
That is a FACT of history and there are many of us that are determined
to respect it.
On what grounds do you support the revocation of planetary status for
Ceres, Vesta, Juno and Pallas, but reject it for Pluto? In other words,
why is it a fact that Pluto is the 9th planet, and not the 13th?
Because they are a different kettle of fish altogether.
Rather than channelling your friendly neighbourhood creationist, Would
you care to specify the grounds, instead of merely asserting that they
exist.
1) Every asteroid is far smaller than Pluto.
The four largest asteroids were listed as planets for many years in the
first part of the 19th century. We no longer list them as planets **because
we found out more about this particular category of object, mainly that
there are many more than the original first four.**
So a historical initial listing of a small body as a planet doesn't mean
that it should be a planet forever if compelling new evidence about its
classification becomes available.
|
True.
| Quote: |
2) No asteroid has an atmosphere, Pluto does.
Very minor objection. Mercury is clearly a planet, but has no atmosphere
other than what is sputtered off the surface rocks by the solar wind.
At least one moon (Titan) has an extensive atmosphere, but it is a moon not
a planet. So having an atmosphere is not a clincher here.
|
But it does differentiate Pluto from the asteroids.
| Quote: |
3) No asteroid has a moon, Pluto does.
Many asteroids have companion satellites; you are out of date here.
|
See an earlier answer I've given.
| Quote: |
4) Only one asteroid is near spherical, both Pluto and its moon are
spherical.
At least one of the large Kuiper belt objects seems to be very
non-spherical.
|
Then it should be considered as a planet.
| Quote: |
5) The definition of a planet as declared by the IAU in 2006 is open
to great debate because, if used, several of the bigger planets fail
the third test. The Earth's orbit is not clear for example.
"Cleared" means that the orbit is dominated by the planet; it is clear in
the same way that a busy road is "cleared" of pedestrians by vehicular
traffic, but you still get jaywalkers. There is a co-orbital asteroid
(Cruithne) which is prevented by Earth's gravity from actually colliding.
(It's a bit complicated to explain).
|
See http://en.wikipedia.org/wiki/3753_Cruithne for some interesting
animations.
| Quote: |
Agreed that this is not the best way to phrase a complicated dynamical
situation. That's what you get when a committee tries to please everyone.
The situation came to a head when a new KBO was discovered that was larger
than Pluto. Since Pluto's discovery, when initially it was thought to be a
lot larger than it really is (much smaller than our own moon), many such
objects have been found. So was it a planet, or yet another example of a
large but not "planetary" object, at the fringes of the solar system? And
if so, wouldn't that mean that Pluto is nto a planet, but the
first-discovered member of a new class of objects?
|
My personal view, based on a reasonable amount of study, is that Pluto
is a planet and that other KBOs should also be added to the list of
planets.
| Quote: |
Sometimes definitions have to change in the light of new discoveries. I
suppose we could let emotion rule our decisions here, but is it a good or
useful way to do science?
|
But what "new discoveries" have really changed the nature of Pluto?
--
Bob. |
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Mike Dworetsky
Guest
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| Posted: Fri Jun 13, 2008 11:00 am Post subject: Re: Pluto, like Eris, is now a "Plutoid" |
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"Zaius" <craig@techapps.net> wrote in message
news:057d8b36-59d8-471a-ba80-a88913bd676b@p25g2000hsf.googlegroups.com...
| Quote: |
On Jun 12, 2:13 pm, Earle Jones <earle.jo...@comcast.net> wrote:
In article
5ac79a5b-c0d0-4edf-851e-32ea35c5d...@z66g2000hsc.googlegroups.com>,
The Last Conformist <andre...@gmail.com> wrote:
On Jun 12, 3:23 am, Glend <interelectromagne...@yahoo.com> wrote:
[snip]
So on the whole, I myself prefer "plutoid" to "dwarf planet".
Please note that plutoids are a subset of dwarf planets - specifically
those dwarf planets with a semimajor axis greater than Neptune's. This
means that Ceres is a dwarf planet but not a plutoid.
IAU link:
http://www.iau.org/public_press/news/release/iau0804/
*
They took away your Pluto.
Next, they're coming after Uranus.
earle
*
They came first for Pluto, And I didn’t speak up because I wasn’t a
planetoid;
Then they came for Uranus, And I didn’t speak up because I wasn’t a
gas giant;
|
Actually, they came first for the asteroids, which were initially classified
as planets until they became too numerous.
--
Mike Dworetsky
(Remove pants sp*mbl*ck to reply) |
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Mike Dworetsky
Guest
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| Posted: Fri Jun 13, 2008 11:00 am Post subject: Re: Pluto, like Eris, is now a "Plutoid" |
|
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"Ye Old One" <usenet@mcsuk.net> wrote in message
news:gc1354td9umu51vk4cludsis3kichev7d3@4ax.com...
| Quote: |
On Thu, 12 Jun 2008 18:41:35 +0100, Ernest Major
{$to$}@meden.demon.co.uk> enriched this group when s/he wrote:
In message <m4l254df2uv99nn11iu5562bg13qnknjc4@4ax.com>, Ye Old One
usenet@mcsuk.net> writes
On Thu, 12 Jun 2008 15:18:17 +0100, Ernest Major
{$to$}@meden.demon.co.uk> enriched this group when s/he wrote:
In message <ed52545dgof1778jivhuaretkbboc10cng@4ax.com>, Ye Old One
usenet@mcsuk.net> writes
On Thu, 12 Jun 2008 05:01:17 -0700 (PDT), The Last Conformist
andreasj@gmail.com> enriched this group when s/he wrote:
On Jun 12, 3:23 am, Glend <interelectromagne...@yahoo.com> wrote:
[snip]
So on the whole, I myself prefer "plutoid" to "dwarf planet".
Please note that plutoids are a subset of dwarf planets - specifically
those dwarf planets with a semimajor axis greater than Neptune's. This
means that Ceres is a dwarf planet but not a plutoid.
IAU link:
http://www.iau.org/public_press/news/release/iau0804/
Pluto is the ninth planet of our Solar System. It was discovered by
Clyde W. Tombaugh on February 18th 1930.
That is a FACT of history and there are many of us that are determined
to respect it.
On what grounds do you support the revocation of planetary status for
Ceres, Vesta, Juno and Pallas, but reject it for Pluto? In other words,
why is it a fact that Pluto is the 9th planet, and not the 13th?
Because they are a different kettle of fish altogether.
Rather than channelling your friendly neighbourhood creationist, Would
you care to specify the grounds, instead of merely asserting that they
exist.
1) Every asteroid is far smaller than Pluto.
|
The four largest asteroids were listed as planets for many years in the
first part of the 19th century. We no longer list them as planets **because
we found out more about this particular category of object, mainly that
there are many more than the original first four.**
So a historical initial listing of a small body as a planet doesn't mean
that it should be a planet forever if compelling new evidence about its
classification becomes available.
| Quote: |
2) No asteroid has an atmosphere, Pluto does.
|
Very minor objection. Mercury is clearly a planet, but has no atmosphere
other than what is sputtered off the surface rocks by the solar wind.
At least one moon (Titan) has an extensive atmosphere, but it is a moon not
a planet. So having an atmosphere is not a clincher here.
| Quote: |
3) No asteroid has a moon, Pluto does.
|
Many asteroids have companion satellites; you are out of date here.
| Quote: |
4) Only one asteroid is near spherical, both Pluto and its moon are
spherical.
|
At least one of the large Kuiper belt objects seems to be very
non-spherical.
| Quote: |
5) The definition of a planet as declared by the IAU in 2006 is open
to great debate because, if used, several of the bigger planets fail
the third test. The Earth's orbit is not clear for example.
|
"Cleared" means that the orbit is dominated by the planet; it is clear in
the same way that a busy road is "cleared" of pedestrians by vehicular
traffic, but you still get jaywalkers. There is a co-orbital asteroid
(Cruithne) which is prevented by Earth's gravity from actually colliding.
(It's a bit complicated to explain).
Agreed that this is not the best way to phrase a complicated dynamical
situation. That's what you get when a committee tries to please everyone.
The situation came to a head when a new KBO was discovered that was larger
than Pluto. Since Pluto's discovery, when initially it was thought to be a
lot larger than it really is (much smaller than our own moon), many such
objects have been found. So was it a planet, or yet another example of a
large but not "planetary" object, at the fringes of the solar system? And
if so, wouldn't that mean that Pluto is nto a planet, but the
first-discovered member of a new class of objects?
Sometimes definitions have to change in the light of new discoveries. I
suppose we could let emotion rule our decisions here, but is it a good or
useful way to do science?
--
Mike Dworetsky
(Remove pants sp*mbl*ck to reply) |
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raven1
Guest
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| Posted: Fri Jun 13, 2008 11:00 am Post subject: Chez Watt! (was Re: Pluto, like Eris, is now a "Plutoid") |
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On Thu, 12 Jun 2008 19:50:19 -0700 (PDT), Zaius <craig@techapps.net>
wrote:
In the category of "Neglecting to cover Uranus":
| Quote: |
They took away your Pluto.
Next, they're coming after Uranus.
They came first for Pluto, And I didn’t speak up because I wasn’t a
planetoid;
Then they came for Uranus, And I didn’t speak up because I wasn’t a
gas giant |
|
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