Should Pluto be reinstated as a planet?

[freeztar]

Whenever people have brought up the subject of pluto and if it is a planet or not, I just say that we will wait until New Horizons gets to pluto and it will solve the argument once and for all :-)

 

Do you know when it's supposed to get to Pluto? It looks like it is almost to Uranus' orbit.

 

 

Source: Heavens-Above.com

[Theory5]

Given that New Horizons is roughly 14 AU away from the sun, I would say its probably between saturn and uranus right now because uranus is usually roughly 19 AU away from the sun.

[Moontanman]

Just exercising my sense of humor guys, (not to mention my imagination, if FTL is impossible we need to make other plans!) forgive me. I think Pluto is an example of a different class of planets just like Jupiter is an example of a giant planet, a class of planets different from the rocky inner planets. It seems a little disingenuous to claim Pluto is not a planet and then call it a dwarf "planet". Dwarf, rocky, giant, they are still planets. Personally I think Ceres (if it turns out to be differentiated into a core and mantle type set up) should at least be called a rocky dwarf planet if not a straight up rocky planet. Pluto should be an ice dwarf along with the other large bodies of mostly ices that inhabit the solar system but do not orbit other planets. I'm not sure what the size cut off should be but I think a planet should be more than a pile of rubble and spherical at the very least. What if we find an ice planet that is Earth mass in size? At that distance from the sun it could have a hydrogen/helium atmosphere, would that still be an "ice dwarf" ?

[freeztar]

This reminds me of Botanical explorations into nomenclature.

When does a flower become another species? How should we group them? etc.

We can now do DNA testing easily, but is it the end all be all?

What about phenology and phylogeny?

 

When is an iceball considered a planet? It has eccentric orbit and is way way far away from the sun, yet it orbits the sun. Perhaps we might call it a "regular collective comet". Seems more fitting. :eek:

 

I pseudo-vote no. I'm withholding my actual vote for any swaying arguments that may come. :)

[Southtown]

Moon stated my case better than I did. Why is a 'dwarf planet' not considered a 'planet?'

[Boerseun]

I just read an article about a suicidal Jupiter-sized planet that orbits its star in less than one Earth day. It creates massive tidal plasma bulges on both the planet and the star, and is expected to finally commit suicide by plunging into its sun in the next million years by its decaying orbit.

 

The more we learn from planets in other solar systems, the less it seems as if our layout is the norm.

 

Rocky planets, apparently, don't always develop in the inside track of the planetary plane, and giants not necessarily on the outside.

 

When we want to create a planetary taxonomy that would apply to all stars and planet systems in the galaxy, then all bets are off.

 

I'm sure our planetary system is about as odd and freakish to any other civilization out there, as theirs would be to ours.

 

I'm of the opinion that if Kepler can determine its orbit, then its a planet. They just vary greatly in size and composition.

 

If you think about it, if a paperclip is orbiting the sun in a straight-forward Keplerian orbit, it clearly is not a planet. But keep on adding paperclips until you have a ball of paperclips the size and density of the Earth. That would definitely be a planet. But between adding which two paperclips did it progress from being an orbiting "ball of paperclips" to being a bona-fide "planet"?

[Southtown]

Whenever people have brought up the subject of pluto and if it is a planet or not, I just say that we will wait until New Horizons gets to pluto and it will solve the argument once and for all :-)

Do you know when it's supposed to get to Pluto? It looks like it is almost to Uranus' orbit.

July 2015. I just watched a Naked Science: Pluto Rediscovered on hulu.

 

Hulu - Naked Science: Pluto Rediscovered - Watch the full episode now.@@AMEPARAM@@http://www.hulu.com/embed/eUzGSFyW-Xg3LEhXq0yeNg@@AMEPARAM@@eUzGSFyW-Xg3LEhXq0yeNg http://www.hulu.com/watch/91794/naked-science-pluto-rediscovered

[Pyrotex]

...Clyde Tombaugh, who discovered the planet-now-dwarf-planet, was born in Illinois.

...Meanwhile, New Mexico's House of Representatives proclaimed February 18, 2009, as "Pluto is a Planet in New Mexico Day" and praised Tombaugh, who worked in the state for decades and died there in 1997.

I had the distinct pleasure of meeting Clyde Tombaugh back in about 1990 or 1991.

 

It was in Houston, Texas, at the McDonnell Douglas building, near the NASA Johnson Space Center.

I was working on the Space Station Freedom project, and Clyde was invited to "bless" our efforts. He sat through several briefings, including one that I gave on the science that we were planning to do from the space station.

Somewhere, I have a picture of me shaking hands with Clyde.

He was a very patient and gracious guest. I'm sure he had to put up with a lot of silliness that day.

 

Did you know that Clyde was good friends with the science fiction writer, Robert A Heinlein?

Yes, indeed they were. In fact, in his short stories and novels, Robert often named the first or the biggest colony on the Moon, "Tombaugh Station".

 

I'll try to find that picture.

[DougF]

I think a 'dwarf planet' should be considered a 'planet?' :)

I Voted Yes!

[modest]

If you think about it, if a paperclip is orbiting the sun in a straight-forward Keplerian orbit, it clearly is not a planet. But keep on adding paperclips until you have a ball of paperclips the size and density of the Earth. That would definitely be a planet. But between adding which two paperclips did it progress from being an orbiting "ball of paperclips" to being a bona-fide "planet"?

 

I think what you say there is key.

 

Whatever definition we give "planet", it needs to be well-enough defined to answer the above question. The current definition given by the IAU would say that it becomes a planet when it is capable of clearing the neighborhood around its orbit. I'm ok with that, but those voting yes should probably have some other determining factor for when a ball of paperclips become a planet.

 

I'm not sure how well it would work to say that anything being rounded by its own gravity would qualify. There are currently 70 such candidates and the list is estimated to expand to approximately 2,000.

 

List of dwarf planet candidates - Wikipedia, the free encyclopedia

 

I wouldn't want there to be 2,000 planets, so if Pluto is to be a planet then I'd think we need some way of setting a cutoff such that the number of planets could realistically be no greater than a few dozen even as we make new discoveries.

 

Any ideas?

 

Then again, maybe the people voting yes are not troubled by the prospect of a few thousand planets... :)

 

~modest

[Southtown]

I have no qualms with 2k planets. Whatever meets a certain definition, knowhatimean?

"

Although the EC's original proposal seems simple and based on physical concepts (a planet is massive enough to be rounded by its gravity, orbits a star, and is neither a star nor a satellite of a planet), the definition stirred controversy among the planetary community. The challenge: under the new definition, there could soon be dozens of new 'planets' in our solar system. That struck many astronomers as the wrong result.

" –

SPACE.com -- Planetary Definition Showdown! As Debate Rages, One Astronomer Says 'It's All About the Atmosphere'

[Moontanman]

I'm intrigued by the idea of being able to hold an atmosphere as a requirement for planetary status. this would mean that Pluto is a planet, as are many of the objects similar to Pluto via the low temperatures that far from the sun. By that definition Titan is also a planet. I think that for the most part people are looking for definitions that maintain the status quo of 9 planets.

[Southtown]

By that definition Titan is also a planet.

Well also planets have to orbit stars, otherwise it's a moon. Ignoring that prerequisite would create all sorts of problems.

[DFINITLYDISTRUBD]

ehn...The only planets that matter are those which can be inhabited or made habitable (through whatever means it can be achieved) by humans... it would most royally suck very much bad to have to memorize the names thousands of stones with grandiose delusions of planetary grandness.

[Southtown]

Well yeah. lol But the 'rounded by its own gravity' (I forget the technical term) stipulation remedies that scenario.

[CraigD]

My favorite aspect of the “Pluto is/isn’t a planet” “controversy” is it’s lack of seriousness. From scientists to politicians to most laypeople, whether Pluto is officially classified as a planet, dwarf planet, a KBO, SDO, TNO, Plutoid, or any of a wealth of classifications, isn’t, I think, of much consequence. The controversy is less of a debate than an opportunity to learn more about astronomy.

 

Nonetheless, I think the controversy would have long been a mere historic curiosity, if 16th century astronomy had moved toward the taxonomological rigor that biology did by the 18th century. The whole Pluto controversy is essentially about nomenclature – naming. We have descriptive, widely accepted terms for Sun-orbiting bodies such as “gas giant planet” that doesn’t “disqualify” its referents from the supercategory of “planets”, but the new “dwarf planet” term seems to be taken as in some sense derogatory. Why gas giant planets are considered planets, but dwarf planets not, strikes me as an twist of language and psychology. I’m puzzled that most people don’t share DougF’s opinion:

I think a 'dwarf planet' should be considered a 'planet?'

Perhaps the IAU definition of “planet” would have fared better with astronomers and the public at large if it had promoted an multi-word term like “orbit clearing planet” rather than restricting the definition of the canonic term “planet”. “The Solar System has only eight orbit-clearing planets” strikes me as less provocative than “The Solar System has only eight planets”.

 

Methinks maybe the roots of the controversy go back much further, to the unfortunate Copernican revolutionary choice to acknowledge the similar nature of the Earth and five other known Sun-orbiting bodies by terming them all “planets”. Planet, most of us know, is a Greek word for “wanderer”, descriptive of their irregular motion as viewed in the Earth’s sky. Terming Earth a “wanderer” was somewhat analogous to acknowledging the anatomical kinship between humans and birds by calling humans birds. :)

 

We could, therefore, reclaim the old, old school definition of “planet” as an object visible with the naked eye that moves relative to the stars. We’d then have somewhere from five to ten or so, depending on whether the Moon (or even the Sun) is included, and whether object that an extraordinarily sharp-eyed person can detect given precise directions where to look. By this definition, +5.4 visible magnitude Vesta is a planet, while +5.5 Uranus might not be, and +7.8 magnitude Neptune certainly isn’t. +13.7 magnitude Pluto – forgettaboutit.

[modest]

Well yeah. lol But the 'rounded by its own gravity' (I forget the technical term) stipulation remedies that scenario.

 

I don't see how. Icy planetoids are rounded by their own gravity at only 200 - 400 km, rocky planetoids at around 900 km. The current list of such 'candidates' in the solar system is greater than 70 and the list is expected to expand to 2,000:

However, based on present knowledge of how icy bodies gravitationally relax into equilibrium shapes, there are a significant number of potential candidates amongst the population of trans-Neptunian objects (TNOs).[4] There were some 70 candidates as of 2008, but it is possible that this number will increase to as many as 2000.

List of dwarf planet candidates - Wikipedia, the free encyclopedia

 

If we want to keep the number of planets below ~1,000 we need some further stipulation to the definition than hydrostatic equilibrium.

 

~modest