"Who want's to see our Moon become designated as a planet? It will eventually meet all the criterea..."<br />I'd be surprised if <i>anyone</i> on this board sees the Moon become a planet! That wouldn't happen for some 4 billion years or so!<br /><br />Really! The <i>entire</i> span of human recorded history is only 5,000 years! Do you honestly think this definition is going to last for the next 5,000, let alone 4 billion, years? No-one for the foreseeable future is going to see a Moon become a planet by way of orbital recession - let's have a definition that's usable for our current needs and in the light of our current knowledge. The unimaginably far future can take care of itself!<br /><br />"I really like that the new proposal keeps the planet designation only for the largest and most significant members of Solar Systems..."<br /><br />Most significant? To whom? And defined as....?<br /><br />Anyway, it's not even true. Imagine a solar system with five objects the size of Ceres, and two objects the size of Jupiter orbiting each other whilst going round their star. And nothing else apart from some small asteroids, comets etc.<br /><br />The five Ceres-sized objects would be planets by the new definition, but the two Jupiter-sized ones would not!
- Status
If we are to have a taxonomy of planets it simply must include moons as well in the definition. Which two objects have more in common, jupiter and ceres, or the moon and mercury ? My definition would center around an ordering of the planets, 0 order = stray planets or those floating in free space, first oder = planets orbiting stars, second order planets ordering first order planets. the ordering could be placed on a log scale, so for example planets with erratic orbits, or twin planets, would have an intermediate ordering (say 1.3). A suffix would then be used to apply a roddenberry like system, so for example you would have 1G for planets like jupiter and saturn (gas giants), 1T for terrestrials like earth and venus, and 2T for bodies such as titan and ganymede. the taxonomy must be comprehensive for it to make any sense, and should not exclude objects on the basis of their orbital characteristics, since this has no bearing on their physical characteristics. We should use maybe a term such as planetoid instead of planet and moon.
The moon should be included simply because it is a significant object which has much in common with a terrestrial (currently acepted) planet. Indeed, if current theories surrounding the fomration of the moon are to be believed, we will have no choice but to include it as such, since physically the moon has much in common with earth. Ignoring satellites in planetary definitions is rather like excluding sea mammals from taxonomies of mammals, simply because they live in the sea. Its plain daft.
Moon is cause of human astronomy.When men first looked at night sky the thing impressed them is moon changes position,varies in size.It gives light ,gives tides .Only then interest in stars came.The moon is source of inspiration for mans finer side.Thousands of years we love the moon.Calling moon anything else is departure from tradition of civilisation.There is only one moon in solar system.Satellites are satellites,astronomically they are not moonsAstronomically they are satellites only..We retain the real moon.
One might want to call moons planets at the same time. <div class="Discussion_UserSignature"> </div>
alokmohan;<br /><br />The Moon (capital M) is the Earth's moon. That's the difference between a moon and The Moon.
Perhaps they should classify planets according to the number of songs written in italian about them - oh dear, I think "La Luna" will win that hands down :-(. <br /><br />
That's actually an interesting idea for taxonomy. I highly doubt the public and astronomers would go for categories such as 1T, 2D, 1G, etc though. In conversation, you'd have to fully explain what you mean by 1T...whereas if you mentioned "gas giant planet", most would immediately know what kind of object you're talking about. So I don't think that classification will work in the near future.<br /><br />I used to favor calling moons planets for the same reasons you argue, and I still think you make great points. If we do totally disregard orbit for planets and adopt moons as planets, I don't think the term moon would vanish. I don't think it should -- we need a term or prefix to distinguish those round bodies that orbit other round bodies. Moon is already widely accepted as this term, so I say stick with it. But can we call them moons and still officially recognize them as planets? Possibly. It means you have a class of planets called "satellite planets" or more likely "moons." This is okay, but then in fairness, we should have a similar nickname for star-orbiting planets. And we don't right now...can't think of any that would stick like moon does. <br /><br />So rogue planets, moon planets, and...uh, planets?<br /><br />It's one of the better ideas, but doesn't quite make an appeal to me, just seems a little too awkward. It also hampers the nice idea of sub-categorizing planets by size (giant, terrestrial, dwarf)...including moons means "a terrestrial moon planet" alongside a "terrestrial planet" and a "dwarf rogue planet." Just gets too messy. This is all in my own opinion. Like I said, it's a good attempt and maybe this suits some people, just not me. <br /><br />Personally, I think we can lump planets, rogues, and moons (all seperate classes) under one large-scale class called planemos. The term planemo can be used to describe...in general terms...any non-fusing spheroid. Planemo is then sub-divided into those 3 classes based on orbit. Those classes can then each neat
I actually think that kids excitement is just no reason for choosing terminology even if I can see dad's excitement over new sparked interests in new planets. It is just bad as criterion for choosing that way. <br /><br />A prominent Czech astronomer Jiri Grygar expressed big misgivings before today's vote on the issue over the proposed naming and would like the voting to be put off to some future ocasion. He thinks that proposed definition will in short time lead to many additional planets as more bodies are discovered and that even if it is accepted, that there will be a lot od disent in future and the definition will have to be reworked again, probably sooner than later...<br />BTW he is not some ivory tower astronomer but a well known populizer of astronomy <br />he also doesn't like that idea about the common center of gravity of orbiting moon to be within a planet for it to be called moon, I myself find it too technical point to bring in as deciding point plus we'll have way too many crazy planets that way<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>
I have had a periodicity which probably should be used to define planets available to anyone since ~2001 on the internet. Looking for some feedback?<br />http://www.1ceres.com/<br />
http://www.int.iol.co.za/index.php?newslett=1&em=52618a6a20060823ah&click_id=31&art_id=qw1156278422680B252&set_id=1.YOU may like to read this also.The debate has caused a big bang in its word.
So double planets do not exist? Btw, the definition has of course no been made for kids 
. An easy, yet not oversimplifcated, way of defining planets without years of bureaucracy. <div class="Discussion_UserSignature"> </div>
. An easy, yet not oversimplifcated, way of defining planets without years of bureaucracy. <div class="Discussion_UserSignature"> </div>dunno about double planets, not around here anyway<br /><br />I'd say talk about double planets when they really tumble around each other, the barycenter above surface condition is to me what bureaucracy is precisely all about with things decided simply by consulting preset rules and a particular context and common sense be damned<br /><br />as I see it, planethood should be decided (when controversy exists) by vote, one voting open to general public and another to professional astronomers and maybe the professional vote would cary more weight and that would settle things<br /><br />thing is, this particular terminology is in place ultimately for us people, for our convenience, science won't be worse off for it if we decide just as we feel like it in this departement <br /><br />it doesn't have to be technically justified by some hard and fast set criteria what is and what is not planet, IMO tradition should be looked to and respected here and if Pluto has been called planet so far, it should remain one, period<br />the other objects out there we might include or not, as we feel and reason about them and decided by that vote I mentioned<br /><br />problem is people seem to crave bureaucratic hard and fast rules written in black and white even where they are not warranted, nature in this case just doesn't cooperate and what we call planets has more to do with our human, that is by and large non-scientific commonsense viewpoint than anything else<br /><br />we should not make any hard and fast rules here precisely because there is longstanding controversy over the issue indicating that no satisfactory resolution by some made up rules is not going to satisfy even the majority of debaters<br /><br />as for me personally, astronomy is not my pet subject, I am only concerned with it as far as physics goes and I don't really care much what is decided, ultimately I will think for myself what is a planet and what is not, after all much worse things have happened in the world than this, it <div class="Discussion_UserSignature"> </div>
Pluto was christened in 1930.Due to wrong thinking that it Lowells planet ,scientists called it planet.Why should Pluto sffer for fault of Clyde Tombough?The later expired few years back.But pluto shall not pay for his mistakes.
I don't think Pluto cares what scientists or the general public thinks <img src="/images/icons/smile.gif" />. Pluto will carry on and do it's thing wether we call it a planet or not. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
BTW -- I've heard from a knowledgeable source that they've decided to drop the word "Pluton" from consideration because the geologists were ticked...<br /><br />Revised proposals now under review look to demote Pluto -- and today's (Thur.) vote may be delayed to work out last minute details. <img src="/images/icons/rolleyes.gif" /><br /><br />------<br />OK; now it seems that the members will vote on "Several" proposals... <img src="/images/icons/rolleyes.gif" /><img src="/images/icons/rolleyes.gif" /><br /><br />Here's a diagram of a "Possible" New Solar System!<br /><br />A "Real" Planetary Classification List!<br /><br /><br />----------------------------------<br />I believe this is the "FINAL" wording of what the IAU members will be voting on:<br /><br />Final Version of Resolution on the Definition of a Planet At the second session of the General Assembly which will be held 14:00 Thursday August 24 in the Congress Hall, members of the IAU will vote on the resolutions presented here. There will be separate sequential votes on Resolution 5A and Resolution 5B. <br /><br />Similarly, there will be separate votes on Resolutions 6A and 6B. Resolution 5A is the principal definition for the IAU usage of “planet” and related terms. Resolution 5B adds the word “classical” to the collective name of the eight planets Mercury through Neptune. <br /><br />Resolution 6A creates for IAU usage a new class of objects, for which Pluto is the proto-type. Resolution 6B introduces the name “plutonian objects” for this class. <br />The Merriam-Webster dictionary defines “plutonian” as: Main Entry: plu•to•ni•an <br />– Pronunciation: plü-’tO-nE-&n – Function: adjective – Usage: often capitalized – : of, relating to, or characteristic of Pluto or the lower world. <br /> <br />Resolutions Committee members will be available at the IAU Exhibit (situ
The formal proposal on the IAU website is here.<br /><br />I can't see 5A not passing, so the important resolution is 5B. If it passes, then we have 'classical planets' and 'dwarf planets' - i.e. two categories of planet - so that Pluto (and other objects) is a planet, albeit a dwarf one. If it fails, we have 'planets' and 'dwarf planets' - i..e they are distinct - so that Pluto is not a planet.<br /><br />It's now down to the plurality of astronomers. We shall see what the non-planetary astronomers think of the matter.<br /><br />(To be honest, I think that whichever way 5B goes, the public are going to regard both planets and dwarf planets <i>as</i> planets, because that is the way English is generally constructed. If 5B fails, I foresee plenty of people trying to explain the solar system to the public starting sentences with: 'Yes, I know it has the word planet in it, but a dwarf planets isn't a planet because [insert explanation of your choice here]".)<br /><br />ETA - According to Newscientistspace, a group of astronomers wanted to chagne the resolution to substitute plenetino instead of dward planet. The reason is obvious - that no matter which way 5B goes, Pluto would then not be a planet, which is why Newscientistspace thinks the IAU Executive Committee will not accept the amendment.
"A prominent Czech astronomer Jiri Grygar expressed big misgivings before today's vote on the issue over the proposed naming and would like the voting to be put off to some future ocasion. He thinks that proposed definition will in short time lead to many additional planets as more bodies are discovered "<br /><br />I don't consider him prominent, five years ago possibly, not today. While his rif raf about a high amount of objects might be valid, it looks like he want to gain prestige by talking.<br /><br /><br />
There isn't as much bureacracy in finding barycenter as finding out whether the "neihbourhood" is cleaned. And we can't vote for planetary status for every new big object found out there! The numbers of exo planets found every year is gonna increase rapidly with the years. <div class="Discussion_UserSignature"> </div>
Last Updated: Thursday, 24 August 2006, 13:34 GMT 14:34 UK <br /><br /> E-mail this to a friend Printable version <br /> <br />Pluto loses status as a planet <br /> <br />Pluto's status has been contested for many years <br />Astronomers meeting in the Czech capital have voted to strip Pluto of its status as a planet. <br />About 2,500 experts were in Prague for the International Astronomical Union's (IAU) general assembly. <br /><br />Astronomers rejected a proposal that would have retained Pluto as a planet and brought three other objects into the cosmic club. <br /><br />Pluto has been considered a planet since its discovery in 1930 by the American Clyde Tombaugh. <br /><br />The ninth planet will now effectively be airbrushed out of school and university textbooks. <br /><br />The decision was made at a meeting of the International Astronomical Union (IAU) in Prague. The astronomers voted by raising their yellow ballot papers for a count. <br /><br />"The eight planets are Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus and Neptune," said the IAU resolution, which was passed following a week of stormy debate. <br /><br /> PLUTO - A 'DEMOTED PLANET' <br /> <br />Named after underworld god<br />Average of 5.9bn km to Sun<br />Orbits Sun every 248 years<br />Diameter of 2,360km<br />Has at least three moons<br />Rotates every 6.8 days<br />Gravity about 6% of Earth's<br />Surface temperature -233C<br />Nasa probe visits in 2015 <br />The IAU's proposal <br /> <br />
The problem is this definition is even more ambiguous than the first. I don't find it scientific either. Using phrases "like cleared the area." This means we will no doubt find objects as large as Mars that aren't planets around other stars. I think (and have always suspected) that they just wanted to keep planets "sentimental." They just didn't like the idea that the number of planets in the solar system could be double or even triple digit numbers. I guess sentimentality won over scientific reason today.
So does this new definition mean that Earth isn't a planet any more? Because 3753 Cruithne shares its orbit with Earth (along with NEOs that cross Earths orbit), so it could be argued that Earth hasn't "cleared the area" around itself.
No, the new definition is better. There is a very precise definiton of "cleared out":<br /><br />http://xxx.lanl.gov/abs/astro-ph/0608359<br /><br />A planet would be at least 100 times larger than anything else that shares it's orbit.
Still not a good definition. Once the moon leaves Earth's orbit in a few billion years or so, it will probably orbit the sun very near by. The moon has a diameter 27% that of Earth. When this happens Earth will no longer be a planet. I'm sure we will find many examples outside the solar system of such things. Like what about the gas giants in large elliptical orbits. They may cross the orbits of numerous smaller planets that size of Earth and Mars. By this definition those smaller planets wouldn't be planets. Also the gas giant wouldn't be either if it wasn't 100 times bigger. Bad vague definition.
- Status
Similar threads
TRENDING THREADS
-
Basic Error: The accelerating Universe conclusion - reason- Started by Gibsense
- Replies: 188
-
-
-
Definition of Universe requires clarification, to enable discussion
- Started by Catastrophe
- Replies: 38
-
-
Just a couple of questions please about just how far back we can model.- Started by Starstruck
- Replies: 12
Facebook
Twitter
Instagram