Even more heavenly bodies!!

[stephen55]

I just can't get enough of heavenly bodies. Perhaps you are the same, so...

Pluto has yet another moon. Nicknamed P4, the moon was recently discovered a team led by Mark Showalter (SETI Institute) and Douglas Hamilton (University of Maryland).

http://media.skyandtelescope.com/images/Pluto_P4_341px.jpg

http://www.skyandtelescope.com/news/home/125893913.html

So now, Pluto has four moons and the solar system's planetary satellite total increases to 171.

 

[Zeb_Carter]

Well your definition of heavenly bodies and mine are completely different...

This heavenly body has one moon, but does have a couple of surprising peaks on it's surface as well a deep canyon rift at one end.

 

[Handley_Page]

Both are a delight, although for different reasons.

Has Pluto been restore to "planet" status ?

 

[mynameisben]

I don't think you can accurately say that the solar system's planetary satellite total just increased to 171. P4 cannot technically be counted a planetary satellite because P4 does not orbit a planet. It's just another tiny little rock orbiting a demoted planet in the middle of a frozen nowhere.

That's not to say the discovery of P4 is any less astounding. It's a huge technological achievement to build an instrument as sensitive as the Hubble Space Telescope, launch it into orbit, and have it resolve a faint little speck some 3 billion miles away. That's truly amazing!

This whole damn business of naming every celestial body after a Greek or Roman mythological character is tired and has to end somewhere. There are billions of pieces of space junk out there but only a limited number of mytho-names. I'm going to lobby the IAU to officially give P4 the name Styxitinuranus, just because.

 

[stephen55]

Has Pluto been restore to "planet" status ?

No and it never will be. While Pluto's demotion from planet to dwarf planet has generated a lot of press, mostly about scientists with too much time on their hands, it was actually the result of a major conference tasked in part, with the job of defining just what is and what isn't a planet.

According to the International Astronomical Union (IAU), which is the body that makes the rules, solar system planets and dwarf planets are defined as...

(1) A planet is a celestial body that

(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" is a celestial body that

(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape
(c) has not cleared the neighbourhood around its orbit, and
(d) is not a satellite.

http://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf

I don't think you can accurately say that the solar system's planetary satellite total just increased to 171. P4 cannot technically be counted a planetary satellite because P4 does not orbit a planet. It's just another tiny little rock orbiting a demoted planet in the middle of a frozen nowhere.

It's all in the definition. In astronomy, just like any other science, words must have a well defined and understood meaning. P4 is orbiting a dwarf planet. It is a satellite of a dwarf planet and thus is very much a planetary satellite. It just happens to be the satellite of a dwarf planet.

This whole damn business of naming every celestial body after a Greek or Roman mythological character is tired and has to end somewhere. There are billions of pieces of space junk out there but only a limited number of mytho-names. I'm going to lobby the IAU to officially give P4 the name Styxitinuranus, just because.

Good luck with that. The IAU is not known for it's sense of humor. As for "naming every celestial body after a Greek or Roman mythological character", for reasons known only to the IAU (at least they aren't letting me in on the secret) all of the moons of Uranus are named after characters from Shakespeare's plays.

 

[mynameisben]

It's all in the definition. In astronomy, just like any other science, words must have a well defined and understood meaning. P4 is orbiting a dwarf planet. It is a satellite of a dwarf planet and thus is very much a planetary satellite. It just happens to be the satellite of a dwarf planet.

Oh, now you're just splitting hairs. The International Space Station is a satellite. It orbits a real planet. Why not count that too? Then there is the Satellite Motel on Route 66. It may not be in orbit, but it's ON the planet Earth. That makes it planetary in my book. That makes 173.

Yes, one can latch onto whichever definition suits one's fancy and count anything however one wishes. We are both guilty. The IAU is, too.

Good luck with that. The IAU is not known for it's sense of humor. As for "naming every celestial body after a Greek or Roman mythological character", for reasons known only to the IAU (at least they aren't letting me in on the secret) all of the moons of Uranus are named after characters from Shakespeare's plays.

Hey, that's right! I forgot all about the moons of Uranus. Thanks! I shall aim my Illudium Q-36 Space Modulator elsewhere.

 

[Zeb_Carter]

I have to agree with Ben, the International Astronomical Unit is just a bunch of old fuddy duddies swinging their shwing around the room to see what sticks to the wall.

Pun intended.

 

[stephen55]

Hey, that's right! I forgot all about the moons of Uranus. Thanks! I shall aim my Illudium Q-36 Space Modulator elsewhere.

http://www.mobiles5.com/files/wallpapers/9634-Marvin-The-Martian.jpg

Where's my Earth shattering Kaboom!! I want my Earth shattering Kaboom!!

Moving on...

Oh, now you're just splitting hairs. The International Space Station is a satellite. It orbits a real planet. Why not count that too?

Not at all. Definitions in science do not split hairs. They exist partly, to prevent hair-splitting. Call the International Space Station a satellite all you want but to the IAU and to me, it is an artificial satellite.

The primary reason that the IAU, back in 2006, set about rigorously defining planet and dwarf planet was the 2005 discovery of a trans-Neptunian object, in a region of space beyond the Kuiper belt, which was called Eris.

At first, Eris was thought to be more massive than Pluto. (It may or may not be so.) It is also about three times the distance from the sun as Pluto, and thus is highly unlikely to have been born of the same collapsed disk of inter-stellar material that formed the sun and the planets. Pluto, with it's highly eccentric orbit (putting it sometimes inside the orbit of Neptune) and it's orbital inclination 17 degrees off that of the plane of the rest of the planets, is also unlikely to be of solar system origin.

The possibility of a planet larger than Pluto beyond the Kuiper belt, simply brought into question the whole idea of just what is and what isn't a planet. In science, it simply won't do to have definitions that bring about confusion and uncertainty. Appealing to uncertain definitions is a concept that has made wealthy many a lawyer but in science, advocating such uncertainty simply gets you shown the door.

Yes, one can latch onto whichever definition suits one's fancy and count anything however one wishes. We are both guilty. The IAU is, too.

Again, not at all. Feel free to latch onto which ever definition suits your fancy and to count anything you wish. The IAU is not guilty of such behavior and neither am I.

 

[mynameisben]

So, you don't want to count the International Space station as a planetary satellite because it is an "artificial" satellite. But you do want to count P4 as a planetary satellite because Pluto is a "dwarf" planet. There seems to be a fancy-suiting arbitrariness to your non-hair splitting ways.

 

[Zeb_Carter]

So, you don't want to count the International Space station as a planetary satellite because it is an "artificial" satellite. But you do want to count P4 as a planetary satellite because Pluto is a "dwarf" planet. There seems to be a fancy-suiting arbitrariness to your non-hair splitting ways.

Well you know what they say...whoever "they" are.

You can't make a silk purse from a sows ear. And an artificial satellite does not a planetary satellite make. Wait. What? So an artificial satellite is not a planetary satellite because someone made built it?

If it quacks like a duck, waddles like a duck, but it's man made, it's not a duck. No, it's an artificial duck. Better tell that male mallard to quit humpin' you leg then daffy.

 

[stephen55]

So, you don't want to count the International Space station as a planetary satellite because it is an "artificial" satellite. But you do want to count P4 as a planetary satellite because Pluto is a "dwarf" planet. There seems to be a fancy-suiting arbitrariness to your non-hair splitting ways.

Ben, I didn't make up the rules and the rules aren't arbitrary.

If you stand up at a graduate level colloquium in astronomy and start talking about planetary satellites, every one in the room knows exactly what you are talking about. No one will stand up and ask you to define your terms. No one will think that what you are talking about includes the International Space Station.

A while back, in that same astronomy colloquium, if you started to talk about planets, there was legitimate uncertainty about just what exactly you might be talking about. (Jupiter...certainly. Pluto...maybe. Eris...damned if I know.) If that colloquium was about the origin of the planets, the uncertainty of just what is and what isn't a planet would become untenable. Hence, the IAU conference back in 2006 and Resolution B5. Now, everyone in the room knows exactly what a planet is, what it isn't and there is no more confusion.

Giving very specific definitions to terms within any field is necessary (within the field) to avoid confusion. Outsiders often refer to such language as jargon and the word jargon is often tossed out as a disparaging term. Have fun with it. Call it arbitrary and hair-splitting. Just don't show up at a technical conference and expect anyone to agree with you, much less listen in the first place. You can no more call the International Space Station a planetary satellite than you can claim four strikes in baseball. It's against the rules; none of which were made by me.

 

[mynameisben]

Ben, I didn't make up the rules and the rules aren't arbitrary.

If you stand up at a graduate level colloquium in astronomy and start talking about planetary satellites, every one in the room knows exactly what you are talking about. No one will stand up and ask you to define your terms. No one will think that what you are talking about includes the International Space Station.

A while back, in that same astronomy colloquium, if you started to talk about planets, there was legitimate uncertainty about just what exactly you might be talking about. (Jupiter...certainly. Pluto...maybe. Eris...damned if I know.) If that colloquium was about the origin of the planets, the uncertainty of just what is and what isn't a planet would become untenable. Hence, the IAU conference back in 2006 and Resolution B5. Now, everyone in the room knows exactly what a planet is, what it isn't and there is no more confusion.

Giving very specific definitions to terms within any field is necessary (within the field) to avoid confusion. Outsiders often refer to such language as jargon and the word jargon is often tossed out as a disparaging term. Have fun with it. Call it arbitrary and hair-splitting. Just don't show up at a technical conference and expect anyone to agree with you, much less listen in the first place. You can no more call the International Space Station a planetary satellite than you can claim four strikes in baseball. It's against the rules; none of which were made by me.

You know, there isn't a single thing you said up there that I disagree with. Definitions have their value. So be it, amen.

What perplexes me, as it has since the very beginning of this intercourse, is how you can unequivocally state that the count of planetary satellites is now 176 and includes P4. Who says? You're so adept at cut & paste argument. Can you cut and paste here any evidence supporting your claim that the planetary satellite count is now recognized by the IAU to include P4 and officially stands at 176? Granted, the discovery of P4 is still very young, and official word is slow to issue from a genuine authority (your mileage may vary). This lies at the heart of why I consider your count of 176 as fanciful hair splitting. To include P4 as a "planetary satellite" requires you to make an assumption before the fact. It implies that the governing authorities would agree with your assessment that P4 qualifies as a planetary satellite, without contradiction to their carefully worded definitions.

Personally, I do not believe that, if asked, the IAU would include P4 in a planetary satellite count. To do so would undermine their definition of planet, which you took such surprising pains to quote. To claim P4 and Charon, Nix and Hydra had equal standing with Europa, Oberon, Titan and the Moon would weaken the IAU's claim that Pluto is not a full-fledged planet. But never mind what I think. In the absence of an official statement, your count of 176 has no authority to stand on -- without regard to the number of astronomy web sites you may have bookmarked at the ready, without regard to the number of graduate level colloquia you may have attended.

Don't get me wrong. I have read and completely agree with the 2006 IAU definitions for planet, and I agree that Pluto doesn't cut the mustard, for logical, physically fundamentally sound reasons. We're just arguing over how the IAU is gonna count their rocks. You're speculating, and I'm waiting. That's all. Whether the IAU says 175 or 176 doesn't mean a hill of beans to me one way or the other.

 

[stephen55]

Can you cut and paste here any evidence supporting your claim that the planetary satellite count is now recognized by the IAU to include P4 and officially stands at 176? (sic)

I already have.

When I stated that the total of all planetary satellites (now) stands at 171, I took that from the original linked article.

"Astronomers using the Hubble Space Telescope have discovered a new moon orbiting the icy planet Pluto. Designated S/2011 (134340) 1 by the International Astronomical Union — but nicknamed P4 — the newcomer orbits Pluto every 32 days at a distance of about 37,000 miles (59,000 km). This puts it between the paths of Nix and Hydra, two moons found circling Pluto in 2005."

"The discovery brings the tally of Pluto's moons (including Charon, its largest) to four, and the total of all known planetary satellites to 171."

http://www.skyandtelescope.com/news/home/125893913.html

If you want another one...
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[mynameisben]

I already have.

When I stated that the total of all planetary satellites (now) stands at 171, I took that from the original linked article.

"Astronomers using the Hubble Space Telescope have discovered a new moon orbiting the icy planet Pluto. Designated S/2011 (134340) 1 by the International Astronomical Union — but nicknamed P4 — the newcomer orbits Pluto every 32 days at a distance of about 37,000 miles (59,000 km). This puts it between the paths of Nix and Hydra, two moons found circling Pluto in 2005."

"The discovery brings the tally of Pluto's moons (including Charon, its largest) to four, and the total of all known planetary satellites to 171."

http://www.skyandtelescope.com/news/home/125893913.html

If you want another one...
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You already have not.

Your first cited article is the opinion of a Sky & Telescope beat writer, not necessarily the opinion of the IAU. Your second source [wisely] does not even address the issue of whether P4 is a "planetary satellite."

 

[stephen55]

S/2011 (134340) was announced yesterday.

The IAU has yet to give it an official name.

From what I've read, the leading contender for a name is 'Cerberus', and damn!...it's from both Greek and Roman mythology, a multi-headed dog (usually three heads) who guards the gates of the Underworld, preventing those who have crossed the river Styx from ever escaping.

God(s) knows that whatever name the IAU decides on for this planetary satellite, you won't accept it.