Comments on: Halfway to Pluto!

By: HID Kit

HID Kit — Mon, 21 Jun 2010 04:22:43 +0000

I’d be kind of neat to have both the largest asteroid Ceres & the brightest asteroid Vesta (the onlyone visible to the unaided eye) count as dwarf planets. Ceres is certainly round enough but I think Vesta is borderline with a massive crater “chipping” it.

Far as I know the asteroid candidates for asterodis are pretty much limited to those two and Pallas unlike the ice dwarf candidates (Makemake, Haumea, Quaoar) etc .. which a lot more numerous.

By: Bernard

Bernard — Thu, 18 Mar 2010 20:07:37 +0000

The IAU never had the power to demote or promote anything. It is a matter of language. If enough people call Pluto a planet it is. A segment calls it a planet and a segment doesn’t. You can’t rewrite old usage so that suddenly it is wrong. I invented the slowly catching on word Exodwarf and wrote an article about Planet definition on my blog that I am fixing to allow comments.

By: MaDeR

MaDeR — Mon, 11 Jan 2010 11:11:48 +0000

StevoR: your discussion “twelve reasons…” is too long. So I will take it one by one, starting from easiest (yeah, I am lazy ***).

“7. When planetary systems are forming, planetary orbits often cross and interact in unpredictable ways – but this doesn’t stop planets”
Ever heard about so-called “protoplanets”?

“from being planets!”
These objects weren’t planets YET in that moment of solar system history.

Do you have something to say? Or we can now discuss another point from “ELEVEN reasons…”? :>

By: Astroquoter

Astroquoter — Mon, 04 Jan 2010 03:16:31 +0000

“…Marc Buie can very easily imagine what it must be like to walk around on Pluto: with less than 1% of your weight on Earth because of the low gravity, at temperatures of 230 degrees below zero, in the twilight because the Sun is nothing more than a dazzling star in the black sky, across snowfields of methane ice and transparent crystals of frozen nitrogen and with a gigantic moon hanging overhead – at least if you are on the right side of the planet.”
- Page 61, ‘The Hunt For Planet X’, Govert Schilling, Copernicus Books, 2009.

By: Spectroscope

Spectroscope — Sat, 02 Jan 2010 15:34:33 +0000

@ 50 Jack Hagerty :

No worries. Glad to hear it.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 02 Jan 2010 15:32:55 +0000

@ 49. Spectroscope Says:

(I presume you meant DPC’s not asteroids which they’re already classed as MTU! (48) )

You mean here?

“Far as I know the asteroid candidates for ~~asterodis~~ dwarf planets are pretty much limited to those two and Pallas …”

Er .. yes. (Blushes.)

By: Jack Hagerty

Jack Hagerty — Sat, 02 Jan 2010 10:00:24 +0000

Thanks, everyone, for the good health wishes. This is just a garden variety cold (not the “flu” or anything that would garner some sympathy).

It’s ground down to just some sinus pain. Not even enough to keep me away from the keyboard…

- Jack

By: Spectroscope

Spectroscope — Sat, 02 Jan 2010 06:32:00 +0000

^ Vesta ( http://en.wikipedia.org/wiki/4_Vesta) is quite likely not round enough with, yes, a very large crater distorting its shape.

The Dawn spaceprobe (http://en.wikipedia.org/wiki/Dawn_Mission) will give us a good view of Vesta from 2011 when it’s scheduled to start orbiting it – just next year now.

Both Vesta & Pallas (http://en.wikipedia.org/wiki/2_Pallas ) are borderline Dwarf Planet Candidates and, as far as I know, are the only asteroid DPC’s with Ceres currently the very smallest officially recognised dwarf planet (I presume you meant DPC’s not asteroids which they’re already classed as MTU! (48) )

It seems having a mainly icy composition makes it a lot easier to get round than rock does. Pallas appears to be roughly octahedron rather than round and my gut feeling is that it & Vesta will just narrowly miss out on DP-hood but I guess we’ll have to wait & see.

For a list of DPC’s check the Wikipedia page here :

http://en.wikipedia.org/wiki/List_of_dwarf_planet_candidates

Thanks to everyone who wished me & others here a happy new year & same back at y’all. Have a great 2010 everyone.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 02 Jan 2010 05:42:56 +0000

@ 43. Jack Hagerty Says:

40. Plutonium being from Pluto Says: “I take it you mean Eris?”

Actually, I meant Vesta, another asteroid rather than a KBO. I have no idea why I said “Eros.” I blame the cold meds…

Far as I know the asteroid candidates for asterodis are pretty much limited to those two and Pallas unlike the ice dwarf candidates (Makemake, Haumea, Quaoar) etc .. which a lot more numerous.

Hope your feeling better Jack & hope everyone’s got the New Year off to a great start.

By: Plutonium being from Pluto

Plutonium being from Pluto — Fri, 01 Jan 2010 05:35:47 +0000

@ 43. Jack Hagerty Says:

40. Plutonium being from Pluto Says: “I take it you mean Eris?” Actually, I meant Vesta, another asteroid rather than a KBO. I have no idea why I said “Eros.” I blame the cold meds… – Jack

Fair enough. Hope you’re feeling better soon & hope you have a great new year too.

By: StevoR

StevoR — Fri, 01 Jan 2010 05:28:41 +0000

Yes, this discussion – but why call us “crackpots”?

Is it just that you disagree with us or do you have something to actually back up that insult?

What exactly makes my arguments & those of others who see that Pluto is indeed a planet & the IAU got it horribly wrong “crackpottery”? Do tell. Really – I want to know.

By: MaDeR

MaDeR — Fri, 01 Jan 2010 01:49:47 +0000

God, no, not THIS discussion again from Pluto crackpots…

By: Gary Ansorge

Gary Ansorge — Thu, 31 Dec 2009 16:57:31 +0000

43. Jack Hagerty:

Obviously, you were referring to some old Greek definitions of love(Eros, Platanos and Agape).

Have you had YOUR Eros today?

GAry 7

By: Jack Hagerty

Jack Hagerty — Thu, 31 Dec 2009 07:42:52 +0000

40. Plutonium being from Pluto Says: “I take it you mean Eris?”

Actually, I meant Vesta, another asteroid rather than a KBO. I have no idea why I said “Eros.”

I blame the cold meds…

- Jack

By: Plutonium being from Pluto

Plutonium being from Pluto — Thu, 31 Dec 2009 06:05:59 +0000

@ 29. Blizno Says:

I have decided to avoid dying from a car crunching my bicycling self or a gamma-ray burster toasting my planet before I can see Pluto up close. I expect Pluto to look like Mercury with less cratering and with a dusting of frozen atmosphere, but see it I must.

Yeah good idea – you’ll love it! My planet is much better looking than Mercury! We’ve got Moons, rings, craters, cyrovolcanoes – far bigger, more numerous & better than Triton’s, the whole “double planet” scene with Charon & our misty snowing atmosphere. New Horizons is in for a treat and I’m sure you’ll all love what you see.

@ 18. Jack Hagerty Says:

1. Plutonium Says: “hope you like your liquid nitrogen tea just above absolute zero.”

Wouldn’t that make it nitrogen ice by something like 100K?

Er .. yes well spotted – but it all depends on the pressure & a few anti-freezing impurities (ie the “tea” & alcohol) you see. Our kettles are very specially designed!

@ 31. Laurel Kornfeld Says:

… yes, Pluto is definitely a party planet. You should see the jacuzzis and pools some of us Plutonians have.

Oh Hades yes! You’re welcome to come celebrate Earth’s newest year here!

Wishing everyone a Happy New Year & clear skies for 2010 whether they’re on Pluto or Earth or the International Space Station or anywhere else!

By: StevoR

StevoR — Thu, 31 Dec 2009 05:49:45 +0000

For those that haven’t already seen them, here are my :

TWELVE REASONS WHY PLUTO *IS* A PLANET :

1. The orbital clearing condition which is the reason for eliminating Pluto is fatally flawed because it is too hard to define. Strictly speaking this criteria eliminates every object in our solar system from proper planethood as all planets have objects – comets and asteroids crossing their orbits!

2. A reductio ad absurdum approach reveals that this criterion fails because it leads to absurd results ruling out objects we’d clearly consider planets based on their location – an Earth or Jupiter-type planet hypothetically located in the Oort cloud would be excluded yet we’d clearly still call it a planet otherwise!

3. The “dwarf planet-dwarf” star analogy – just as dwarf stars are still stars so surely are dwarf planets still planets. Extrapolating the “dwarf planets don’t count” line to the stellar realm would imply our Sun is not a proper star nor are 99 % of all stars – those 90% on the main-sequence and the 10 % of “stellar corpses” such as white dwarfs and neutron stars.

4. Inconsistency and inapplicability in regard to exoplanets – the IAU definition excluded planets of other stars. Yet surely planets orbiting other suns are no less planets for not orbiting our star! There are also more inconsistencies with at least one planet smaller than Pluto (PSR B 1257+12 e ) known and one exoplanetary situation (HD 45364.) analogous to Neptune-Pluto situation

5. Pluto is a complex world with the key aspects of planets – like the other outer planets (& beating Mercury & Venus) Pluto dominates its own family of three moons (Charon, Hydra & Nix), one of them large enough tobe aworld in its own right – and perhaps even has a system of rings too!

6. Pluto also has its own atmosphere, (unlike Mercury) and has a complex weather system incl. snowfall as well as being geologically (hadeologically?) differentiated and structured. It thus meets all the criteria for planethood with the sole exception of the absurd “orbital clearance” criterion.

7. When planetary systems are forming, planetary orbits often cross and interact in unpredictable ways – but this doesn’t stop planets from being planets! Yet by the IAU’s “orbital clearance” criterion, these objects – even ones Jupiter sized and above – are NOT strictly planets because their orbits are not yet cleared. This situation may later repeat in the distant future too eg. when our Sun passes through the red giant & white dwarf stages.

8. By IAU definitions planets cannot collide because their neighbourhood then isn’t clear. By the same logic nor can they exist as binaries or “double planets” . This appears contrary to common-sense and consistency. It also has potential for creating trouble with the possiblity that some exoplanets may exist in this form – even potentially twin Neptunes or Jupiters. Indeed, given that some would describe the Earth-Moon system as well as the Pluto-Charon one as such a ‘double planet’ then a strict definition of the IAU rule may rule our Earth out of planetary status!

9. The undemocratic manner in which the IAU ruling was made. Of the 10,000 IAU members only 2,500 attended the Prague meeting that demoted Pluto from planetary status. Furthermore, of those 2,500 only the merest handful – just 424 actually got to vote making therefore a very unrepresentative decision. Among those to excluded from voting and arguing their case in that last minute meeting were some highly relevant and articulate people – notably Pluto expert Alan S. Stern, head of the New Horizons mission.

10) The first proposed IAU definition of ‘planet’ (that would have included Pluto, Eris and Ceres) was much better in terms of logical consistency and general application as well as being more easily explained, understand and applied – ie. two main criteria for planets are that they are objects circling a star directly which are not themselves stars or brown dwarfs and are rounded by their own gravity. Other superior definitions to the IAU can also be found all of which include Pluto. (For example see comment # 39 above.)

11) Cultural and historical reasons – noting Pluto’s long-established and culturally scientific place as a recognised planet from its discovery in 1930 until its (hopefully brief) demotion in 2006. These include the slight to Clyde Tombaugh’s memory, widow and family plus the perceived political aspect of stripping from planetary status the sole planet discovered by an American.

12.) The demotion of Pluto has had a massively negative reaction being unpopular with the general public and many astronomers with a large number even refusing to accept the IAU’s authority outright. The IAU demotion of Plto has brought astronomy and science generally into disrepute and threatens to split the astronomical community – it is in their interests then for this mistake to be speedily corrected and Pluto restored to its correct planetary status.

*****

PS. If you think this looks familiar, yes, I’ve posted these ’12 reasons why Plut0 *is* a planet’ before here in other forms & variants before ages ago in past threads but I hope its still okay to post them again here – my apologies if not.

By: Plutonium being from Pluto

Plutonium being from Pluto — Thu, 31 Dec 2009 04:43:25 +0000

@ 34. Jack Hagerty Says:

I believe both Ceres and Eros are now classified as “dwarf planets.” The rationale is that they orbit the sun directly and are large enough to be spherical.

Yes for Ceres there but not for Eros which is a saddle -shaped elongated Near-Earth Asteroid – the one the NEAR-Shoemaker probe explored and landed on some years ago! I take it you mean Eris?

Or did you mean another asteroid? There are a number of possible asteroid belt dwarf planets or candidates for that status – Ceres, Pallas, Vesta and maybe one or two others.

@ 35. Chris A. Says:

@Shawn Smith (33):

“…Ceres was considered a planet for a short time.”

Only if you consider two-thirds of a century to be a short time: Pluto had a slightly longer run as a planet. Big deal. Our knowledge changes. Accept it, move on.

The IAU definition deliberately designed by a tiny anti-Pluto minority of the Prague meeting was NOT a change in knowledge but a political decision that makes little if any scientific sense.

The third criteria for the IAU definition – to do with planets clearing their orbits – is problematic in being vague, hard to define in itself and is illogical & unscientific.

It fails among other things the reductio ad absurdum test of logic because it means that if Earth or even Jupiter was orbiting in the Edgeworth-Kuiper belt they would not be planets either which everyone would agree is absurd.

(In the fact, the planets of Fomalhaut b and those around HR 8799 which were photographed the other year – among others – do NOT count as planets under the IAU definition because of this criteria yet are many times more massive than Jupiter!)

The sole reason that such a, let’s face it, totally unscientific and downright stupid criteria was added to the IAU definition of planet was to exclude Pluto from planethood. This decision was made at the very last minute by just a handful of astronomers with the advocates of Pluto’s planethood – notably Alan Stern – excluded from the final decision and vote.

It was very much NOT a case of knowledge changing but rather a mistake made because of a tiny minority of biased people who, for dubious and illogical reasons that are known only to them had a nasty prejudice against Pluto.

Such mistakes need changing and correcting – the sooner the better for *all* astronomers.

Thngs will move on indeed – because in the future hopefully even the near future we will look back at the aberration of Pluto’s temporary “non-official planethood” and wonder what the blazes those fools were thinking & how they could ever have made such a blatantly wrong, silly decision.

By: StevoR

StevoR — Thu, 31 Dec 2009 04:10:57 +0000

@ 15. Matthew Ota Says:

By the time New Horzons gets to Pluto, perhaps it’s status will have been restored to full planethood…or at least it will get some new respect from planetary scientists.

Me too – agreed 100%.

@ 31. Laurel Kornfeld Says:

Pluto IS a planet. The real paradigm shift some are having trouble adjusting to is a solar system with potentially hundreds of planets instead of eight or nine. Planets are not rare or special; they are everywhere. This is an extension of the Copernican principle. It’s the IAU who are being revisionists by trying to artificially narrow the definition of planet because they cannot deal with the idea of a solar system with numerous planets.

Absolutely spot on & well said.

My definition for a planet – a reasonable definition unlike the ridiculous IAU one – is that an object is a planet if it is :

a) Never self luminous by nuclear fusion thus not a star or brown dwarf,

b) Not directly orbiting another planet thus not a moon

c) Large enough to be round or, if rapidly spinning oblate spheroidal, through its own gravity thus not a comet or asteroid.

Planets can then be divided into various classes & sub-classes depending on their composition and orbital positions such as Gas Giant, Hot Jupiter, Eccentric Orbiter, Hot Neptune, Ice Giant (Neptune-like), Gas Dwarf, Super-Earth, Earth-like or Terrestrial planets & Ice dwarfs.

Our solar systems has three main types of planets each occupying their own zone around our Sun – the rocky, the gassy & the icy!

By my reckoning & classification system (which I make no claims to have invented or anything like that, its really pretty much common sense.) we have four rocky or Earth-like planets, four gas giant or Jovian planets* and many ice dwarf planets of which Pluto, Eris and Makemake are the largest currently known.

Now doesn’t that make more sense – isn’t much better and clearer than the IAU’s mess?

—–

* I like this basic division into the rocky, the gassy & the icy but if you wish to get more technical you can if desired separate the smaller Ice Giants Neptune & Ouranos from the “proper” Gas Giants Jupiter & Saturn. Ceres could be considered an asteroidal planet or an ice dwarf while other candidates for asteroidal planet class include Pallas & Vesta. From an observational viewpoint it can also be useful to use the “Inferior planets /superior planets” division with Mercury & Venus being inferior ie. closer to our Sun & also near it and setting or rising close to twilight. Plus folks can also call the planets visible to the ancient pre-telescopic times “classical” & the later discovered Ouranos, Neptune, Pluto, Ceres, Haumea etc .. post-Telescopic planets and so forth.

Planets – the more, the merrier!

By: Jack Hagerty

Jack Hagerty — Thu, 31 Dec 2009 02:47:24 +0000

36. Alaskana Says: “Is this craft going to orbit Pluto for any amount of time, or is it just going to go cruising by, grabbing as much data as it can while it passes?”

This is a flyby mission. One quick glance, then it’s out of the solar system forever.

Well, not all that quick. I’m sure they will have the observation schedule highly optimized by the time it gets there and will spend months doing “close up” observations both before and after closest approach.

The reason it isn’t an orbiter is time. It’s on a coasting trajectory (i.e. no power, like with an ion engine) so we gave it as big a push as possible and picked up more from Jupiter, and even at that it’s taking over 9 years to get there. To be an orbiter it would have to approach Pluto at roughly its orbital velocity, which is a lot slower than it’s going to be travelling. Halley’s comet travels roughly this orbit (from just inside Earth’s orbit to just outside Neptune’s) and it takes 38 years to make the journey!

- Jack

By: Drei Finalisten für die nächste „New Frontiers“-Mission der NASA « Skyweek Zwei Punkt Null

Wed, 30 Dec 2009 23:21:45 +0000

[...] könnte ein Mitreisender immer noch nicht mit dem bloßen Auge sehen. (Discover, Cosmic Log, Bad Astronomy [...]

By: Alaskana

Alaskana — Wed, 30 Dec 2009 23:09:44 +0000

Is this craft going to orbit Pluto for any amount of time, or is it just going to go cruising by, grabbing as much data as it can while it passes?

By: Chris A.

Chris A. — Wed, 30 Dec 2009 21:27:40 +0000

@Shawn Smith (33):

“…Ceres was considered a planet for a short time.”

Only if you consider two-thirds of a century to be a short time:

Ceres discovered: 1801
Ceres listed as one of 11 planets (also including Vesta, Juno, and Pallas) in “First Steps to Astronomy and Geography”: 1828
Asteroid numbering convention introduced (by Encke), excluding Ceres, Pallas, Vesta, and Juno: 1851
Ceres, Pallas, Juno, and Vesta given asteroid numbers 1-4: 1855
Last listing in the same table with the planets (along with Pallas, Juno, and Vesta) by the Berlin Astronomical Yearbook: 1867

Pluto had a slightly longer run as a planet. Big deal. Our knowledge changes. Accept it, move on.

By: Jack Hagerty

Jack Hagerty — Wed, 30 Dec 2009 20:08:20 +0000

33. Shawn Smith Says: “I think Ceres was considered a planet for a short time”

I believe both Ceres and Eros are now classified as “dwarf planets.” The rationale is that they orbit the sun directly and are large enough to be spherical.

- Jack

By: Shawn Smith

Shawn Smith — Wed, 30 Dec 2009 17:28:33 +0000

Pluto is a satelite of Sol. It is the longest known of the Plutinos / dwarf planets. We don’t call, and almost never have called, any of the asteroid belt objects planets (I think Ceres was considered a planet for a short time). We haven’t called any comets planets. We haven’t called any of the asteroids at Jupiter’s Lagrange points planets. Laurel, it sounds like you are the one who is being a revisionist here, because you apparently want to call all those other things planets. The IAU simply chose some criteria for a definition of “planet” that seemed reasonable, mainly because it didn’t have one before, and it turned out Pluto didn’t meet the criteria. Eris, Makemake, Haumea, and Quaoar don’t meet the criteria either.

Interesting milestone for New Horizons. I also look forward to any information the New Horizons probe can provide us.

By: Gamercow

Gamercow — Wed, 30 Dec 2009 17:20:05 +0000

Pluto is a planet in the same way that a dwarf star is a star. Its just further classification. Therefore, there are 13(8 + Pluto, Haumea, Makemake, Ceres, and Eris?) named known planets in our solar system.