Soon 12 planets in the solar system !

Carsten A. Arnholm wrote:
robin_astro wrote:
Starlord wrote:
is neither a star nor a
satellite of a planet."

That takes Pluto's 3 moons and our moon out of the planet class.



Nope. They have covered this. Charon is a planet (part of a double
planetary system) The other moons stay planetary satellites.

Hi Robin :-)

But the two small moons (Nix and Hydra) can't be planetary satellites, since
they don't orbit a planet, but instead orbit the barycentre of Pluto and
Charon? Don't they?

barycentric satellites?

Hi Carsten

This raises an interesting point about the location of the barycentre
of an n body system. eg in the hypothetical case of a figure of eight
orbit of 3 objects, the barycentre is alternately located at the centre
of each component in turn, moving from one to the other. Does this mean
the objects in such a system would alternate between being planets and
satellites?
see here for a simulation (Java)
http://faculty.ifmo.ru/butikov/Proje...llection4.html

Robin

Paul Schlyter wrote:
The solar system had 12 planets already some 160 years ago.....

After the discovery of (4) Vesta in 1807, no more asteroids were discovered
for 38 years, until (5) Astraea was discovered in 1845.

Then Neptune was discovered in 1846.

Then (6) Hebe was discovered in 1847 .... and since then, new asteroids
were discovered almost each and every year.

But from 1807 to 1844 only 4 asteroids were known. They were counted
among the planets -- thus the solar system had 11 known planets during
this time period. In 1845, the 12th planet, Astraea, was discovered,
and in 1846, the 13th planet, Neptune, was discovered.

In the years following 1846, many more small planets were discovered.
The word "planet" was redefined so it included only the major planets,
reducing the number of known planets in the solar system to 8.

Now, when the word "planet" is about to be redefined again, the solar
system may get 12 known planets for the second time....

Of course, since Quaoar and Sedna are likely *also* big enough to be
spherical, even if they aren't bigger than Pluto, as someone pointed
out, we may get more than 12.

Oh, and this site

http://aa.usno.navy.mil/hilton/Aster...orplanets.html

deals a bit more with this particular fascinating bit of history.

If it is decided to go the other way, perhaps it might be argued that
Pluto should be kept as a 'historic' planet - but then everything up to
Astraea should perhaps be kept too!

Of course, one might have a *three-tier* Solar System, in which Ceres,
being spherical, gets to be a 'minor planet', but all the rest of the
asteroids are now officially asteroids, or something like that.

John Savard

robin_astro wrote:
This raises an interesting point about the location of the barycentre
of an n body system. eg in the hypothetical case of a figure of eight
orbit of 3 objects, the barycentre is alternately located at the centre
of each component in turn, moving from one to the other. Does this mean
the objects in such a system would alternate between being planets and
satellites?

You don't even need that. If Pluto and Charon had orbits that were
elliptical enough, the barycenter could be alternately within and then
outside Pluto. I have to wonder if they're taking this into account,
and using qualifiers like "at perisides" or "at apsides" or "at a
distance equal to semi-major axis," or something like that.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

Davoud wrote:

(....)
"Rich" said "Lets hope nostalgia over Pluto and it's discoverer does
not have any effect on a decision."

I say "Lets hope that an irrational desire to demote Pluto does not
have any effect on a decision."

Why are people so hung up on the need to demote Pluto? Is it
/necessary/ to demean Tombaugh's achievement?
(....)

Demoting whatever......demeaning whomever...-

What does all of this have to do with formulating a SCIENTIFIC - and
that means RATIONAL - definitition of a phenomenon?! Heck, if
paleontologists weren´t allowed to redefine a species once they found
out that their previous definition was insufficient, that science would
be long dead by now!

Some people here are commiting what Kant called a "cathegorical error"
(mingling concepts that belong to different cathegories). You can´t
compare airplanes with regard to their sugar content (even though it
frequently does exist).

This is all so ridiculous .... but also very human and thus forseeable.
Because in distinction to what some (dimwits) claim, we homo sapiens
are by no means rational by nature, but in our essence we are
emotional, irrational and subjective creatures - with a mere potential
for rational behaviour (which includes thought) which some people
cultivate more and others less. Unfortunately, the less they cultivate
it, the more numerous they are. Let´s not allow that science falls
into the hands of these people.

Peter

Davoud,

I agree with you. I've always wondered why there seems to be this
strong anti-pluto
"feeling". It makes no sense at all really.

Now, possibly, the thought has occurred to these gentlemen & ladies
that if they demoted Pluto the whole world might throw the proverbial
"book" at them because no one takes 76 years to finally agree on a
definition.

It's pretty ridiculous in and of itself.

I think the general public might just be able to stomach a few more
planets and say possibly a few more withing a few years as our
telescopes and technology get better and more precise.

Carl Sagan, come back...we need you now!

Ed wrote:
Davoud,

I agree with you. I've always wondered why there seems to be this
strong anti-pluto
"feeling". It makes no sense at all really.

Now, possibly, the thought has occurred to these gentlemen & ladies
that if they demoted Pluto the whole world might throw the proverbial
"book" at them because no one takes 76 years to finally agree on a
definition.

It's pretty ridiculous in and of itself.

I think the general public might just be able to stomach a few more
planets and say possibly a few more withing a few years as our
telescopes and technology get better and more precise.

Carl Sagan, come back...we need you now!

Estimates are 100-200 more based on their criteria. 99% of them beyond
the range of typical amateur telescopes.

In article , Brian Tung wrote:

robin_astro wrote:
This raises an interesting point about the location of the barycentre
of an n body system. eg in the hypothetical case of a figure of eight
orbit of 3 objects, the barycentre is alternately located at the centre
of each component in turn, moving from one to the other. Does this mean
the objects in such a system would alternate between being planets and
satellites?

You don't even need that. If Pluto and Charon had orbits that were
elliptical enough, the barycenter could be alternately within and then
outside Pluto. I have to wonder if they're taking this into account,
and using qualifiers like "at perisides" or "at apsides" or "at a
distance equal to semi-major axis," or something like that.

One could apply a similar definition for planets orbiting a star too:
if the planet+star barycenter resides outside the surface of the star,
then it's a double star rather than a star+planet. Which could get
some weird consequences: as the primary star of a double star system
evolves and grows while approaching the giant phase, it could
"swallow" the barycenter - and then the companion star would suddenly
be degraded to a planet!

The Jupiter+Sun barycenter always resides inside the Sun, so Jupiter
would not become a "star" through such a definition (at least not
until the Sun has evolved into a white dwarf, billions of years from
now). The Sun+Jupiter+Saturn barycenter though sometines resides
outside the surface of the Sun.

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/

Thierry wrote:
Hi,

Soon there will be probably 12 planets in the solar system !
ercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto,
Charon and 2003 UB313
See the latest IAU news at :
http://www.iau2006.org/mirror/www.ia...1_release.html

SNIP
Thierry
http://www.astrosurf.org/lombry





any Astrologers like to comment on how this affects their predictions? :-)

Neil

"Don't Be Evil" writes:

Estimates are 100-200 more based on their criteria. 99% of them beyond
the range of typical amateur telescopes.

Actally, a large fravction of these are accessible to amateur
_equipment_ (telescope+CCD camera). So far, I have imaged 5 of them
(Pluto, Orcus, 2005 FY9, 2003 EL61, and 2003 UB313): all but one
(Orcus, at mag. 19.2) with a 6" telecope and a homebuilt "Cookbook"
camera.

pej
--
Per Erik Jorde

Neil Gwillym wrote:

Thierry wrote:
Hi,

Soon there will be probably 12 planets in the solar system !
ercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto,
Charon and 2003 UB313
See the latest IAU news at :
http://www.iau2006.org/mirror/www.ia...1_release.html

SNIP
Thierry
http://www.astrosurf.org/lombry





any Astrologers like to comment on how this affects their predictions? :-)

Or better on how what "Don't Be Evil" says above would affect them:
"Estimates are 100-200 more based on their criteria. 99% of them
beyond
the range of typical amateur telescopes."

The good thing about this situation is, that it should give astrologers
a hard time. Most of the people which are so hung up with Pluto have
never heard about Tombaugh anyhow, but know about this object through
horoscopes.

And if there is one thing that we all must agree on, then it is that
the opinion of people who believe in horoscopes is just as relevant for
a *rational* definition of what is a planet, as is a sack of rice
falling over in China.