Distant object found orbiting Sun

[Perfection]

Where do you think the line should be drawn as to what consitutes a planet? What if a Mercury-sized KBO were discovered?

Two things:
Size (must be large enough to be spherical)
Orbital uniqueness (most not be in a field of similar bodies of similar size)
Mercury qualifies, big KBOs don't (unless it's really freakin' huge)

 

[Bootstoots]

Two things:
Size (must be large enough to be spherical)
Orbital uniqueness (most not be in a field of similar bodies of similar size)
Mercury qualifies, big KBOs don't (unless it's really freakin' huge)

What if Sedna, with an incredibly distant perihelion and an aphelion that is usually considered outside the Kuiper belt, is actually on its own? Also, this one was discovered at around 97 AU according to the article, making it outside the Kuiper belt as well. Of course, this could also point to another group of bodies outside of the Kuiper belt, or a vastly expanded outer limit to it.

 

[The Last Conformist]

I'd be seriously tempted to drop "planet" as other than a traditional appelation of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

 

[eyrei]

It is most certainly a large Silicoid spaceship. We are doomed...

 

[Perfection]

What if Sedna, with an incredibly distant perihelion and an aphelion that is usually considered outside the Kuiper belt, is actually on its own?

Well, since Sedna's orbital area is absolutly massive (do to it's extreme eccentricity), pretty much anything in the would qualify as something that would remove it from planetary treatment. If it was on it's own then I would likely consider it a planet. Since theory predicts it is not alone, I would not advocate calling it a planet now and then in all likelyhood recinding it later.

Also, this one was discovered at around 97 AU according to the article, making it outside the Kuiper belt as well. Of course, this could also point to another group of bodies outside of the Kuiper belt, or a vastly expanded outer limit to it.

Yeah, this whole class of SDOs intrigues me.

Someday when we get this whole fusion power thing worked out, we should go and colonize all them suckers.

 

[Perfection]

I'd be seriously tempted to drop "planet" as other than a traditional appelation of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

What about exoplanets?

 

[Perfection]

Gosh darn it! Here's another one! http://en.wikipedia.org/wiki/2005_FY9

 

[Winner]

Clearly all KBOs are the same class of objects, so either all or none should be considered planets.

"Planet" isn't really a useful label. Even without Pluto, the traditional set includes two very different categories of objects - jovians and terrestrials -, one of which has more in common with the Moon or Ceres than with the other, except for orbiting the Sun.

Both gas giants and terrestrials have roughly circular orbits in the ecliptic plane. Pluto and other Kuiper belts planetoids doesn't fit these criteria so I wouldn't consider them as planets.

 

[The Last Conformist]

What about exoplanets?

Call them "hot jovians".

I don't really care about what happens to the designation "planet", but the recurrent discussions whether this or that plutonian iceball is a planet or not are stupid and beside the point.

I suppose internal melting + orbital unicity is about as close to a reasonable definition of "planet" we're gonna get, unless we go back to moving permanent object in the sky visible to the naked eye, but the basic problem is that what we traditionally think of as planets don't form a natural group.

Or reserve "planet" for terrestrial bodies, calling gas giants that (or jovians) and iceballs iceballs.

 

[The Last Conformist]

Both gas giants and terrestrials have roughly circular orbits in the ecliptic plane. Pluto and other Kuiper belts planetoids doesn't fit these criteria so I wouldn't consider them as planets.

IIRC, some of the KBO do have nigh-circular orbits in the ecliptic plane.

 

[Perfection]

Well, I think planet is an important term because all 8 share a similar devlopment path and a number of characterestics like considerable gravitational control of thier orbital path and nearby ones.

Though I do see your point that the debate is symantic and taxonomic and not of scientific thoery and the only potential goal is clearer communication

 

[The Last Conformist]

Remind me, is Ceres big enough to've melted it's interior by radiogenic heat?

 

[Perfection]

Remind me, is Ceres big enough to've melted it's interior by radiogenic heat?

Not sure, I poked around the internet a bit and I'm not getting good results.

You wouldn't happen to have an advisory staff of astronomers to go with your biology staff would you?

 

[madviking]

Lets see...
My Very Educated Mom, Sally, Taught Us uhh.... Nothing... Simple?

 

[MarineCorps]

Could it be .... ???

Oh no, not you too. Wyrm think its that planet Niburu.

 

[Perfection]

Anyone who needs a mnemonic device to know the order of the planets isn't cool in my book

Though I will admit to using Met Dr. T? Hip! to remember the order of Saturn's major moons

(Mimas, Enceladus, Tythes, Dione, Rhea, Titan, Hyperion, Iapetus, Pheobe)

Though Hyperion and Pheobe are boderline major.

 

[The Last Conformist]

It's Phoebe.

 

[Perfection]

It's Phoebe.

Now, now, noone likes a spelling-Nazi.

 

[Chieftess]

10th Planet - from CNN

Astronomers claim discovery of solar system's 10th planet

Saturday, July 30, 2005; Posted: 6:39 a.m. EDT (10:39 GMT)


This artist's concept, released by NASA, shows the planet catalogued as 2003UB313.
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Manage Alerts | What Is This? PASADENA, California (CNN) -- A group of astronomers announced Friday that an object they discovered in the distant reaches of the solar system is large enough to be classified as the 10th planet -- a claim likely to reignite a debate over just how many objects should really have the title of planet.

The object -- located 96 times as far from the Earth as the Earth is from the sun, or nearly 9 billion miles away -- was first photographed in October 2003 by astronomers at the California Institute of Technology's Palomar Observatory, north of San Diego.

While researchers say they aren't yet sure of its actual size, they have determined the object is bigger than Pluto, currently the smallest planet and the one most distant from the sun.

"If Pluto is a planet, it seems reasonable that something that's bigger than Pluto, and further away than Pluto, should be called a planet, too," said Mike Brown, a Cal Tech planetary scientist who made the discovery with colleagues Chad Trujillo of the Gemini Observatory and David Rabinowitz of Yale University.

However, a number of astronomers dispute whether Pluto, discovered in 1930, should really be classified as a planet, because it is so dissimilar from the other eight. Instead, they believe it should be classified only as a Kuiper Belt object, part of an array of icy debris in the outer reaches of the solar system.

Thousands of Kuiper objects have been discovered, and more are being found all the time.

Brown concedes that both Pluto and his new planet are Kuiper objects -- but he argues they are also both big enough to be classified as planets.

The International Astronomical Union, the official arbiter of such disputes, has classified Pluto as a planet and recently declined to demote it. Brown said resolving the argument over whether the object his team found is a planet will take years.

Brown's team has submitted a name for its proposed planet to the IAU, which won't be announced until the astronomy group hands down its ruling.

While the object was first photographed in 2003, its motion was not detected until January because it was so far away. Since then, astronomers have been studying the object to estimate its size and motion.

Brown said the planet-sized object probably wasn't discovered earlier because it was in a location where planets aren't expected.

"All of the planets are in a disc around the sun, and this object is 45 degrees out of that disc," he said.

I wonder how many "10th planets" were claimed to have been discovered in the past 10 years.

 

[Perfection]

I wonder how many "10th planets" were claimed to have been discovered in the past 10 years.

Numerous, it's just that Astronomers had the good sense not to consider it a planet. There is no way that this should be the tenth planet. If this is considered the planet, then it's gotta be like the 18th or something because Sedna, Quaoar, 2003 EL61, 2005 FY9, Orcus, Varuna, 2002 TC302 and a bunch of other meaty suckers should be considered planets too