The Gods Have Spoken!

[tfwthom]

The IAU draft definition of "planet" and "plutons"<br /><br />http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html<br /><br />According to the new draft definition, two conditions must be satisfied for an object to be called a "planet." First, the object must be in orbit around a star, while not being itself a star. Second, the object must be large enough (or more technically correct, massive enough) for its own gravity to pull it into a nearly spherical shape. The shape of objects with mass above 5 x 1020 kg and diameter greater than 800 km would normally be determined by self-gravity, but all borderline cases would have to be established by observation.<br /><br /> <br /><br />If the proposed Resolution is passed, the 12 planets in our Solar System will be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and 2003 UB313. The name 2003 UB313 is provisional, as a "real" name has not yet been assigned to this object. A decision and announcement of a new name are likely not to be made during the IAU General Assembly in Prague, but at a later time. The naming procedures depend on the outcome of the Resolution vote. There will most likely be more planets announced by the IAU in the future. Currently a dozen "candidate planets" are listed on IAU's "watchlist" which keeps changing as new objects are found and the physics of the existing candidates becomes better known.<br /><br /> <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[MeteorWayne]

The "Gods" have not spoken, they have proposed a definition to resolve the planetary controversy.<br />It has not been voted on yet.<br />And they are not gods, just a scientific body. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[tfwthom]

I don't think that they have ever failed to confirm a draft in the IAU. So plan on having 12 planets as of Aug 24th between 14:00 and 17:30 CEST. Besides after 2 years of work it would be foolish not to confirm.<br /><br />And they are the Gods of astronomy. (and I don't want to get into religion) <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[harmonicaman]

<b>MeteorWayne -</b><br /><br /><i>"The "Gods" have not spoken, they have proposed a definition to resolve the planetary controversy. <br />It has not been voted on yet."</i><br /><br />Great point; but it sure looks like a fait accompli... <br /><br /><i>"And they are not gods, just a scientific body."</i><br /><br />No; they're Gods... <img src="/images/icons/rolleyes.gif" /> <br /><br /><br />

 

[MeteorWayne]

<i>"And they are not gods, just a scientific body." <br /><br />No; they're Gods... </i><br /><br />Naah, just the poor suckers trying to unscramble the eggs <img src="/images/icons/smile.gif" /><br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[barrykirk]

Where did Sedna fall in this whole mess?

 

[MeteorWayne]

Good question, AFAIK, it would be a "small solar system body" <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[tfwthom]

Table 2: Planet candidates as per 24 August 2006 to be given future consideration if “Resolution 5 for GA-XXVI” is passed. <br /><br /> <br /><br />Object <br /> Unofficial diameter estimate<br /> <br />2003 EL61 <br /> 2000×1000×1200 km(3)<br /> <br />2005 FY9 <br /> 1500±300 km(4)<br /> <br />(90377) Sedna <br /> 1200-1800 km(5)<br /> <br />(90482) Orcus <br /> 1000±200 km(6)<br /> <br />(50000) Quaoar <br /> ~1000 km(7)<br /> <br />(20000) Varuna <br /> 600 ± 150 km(8)<br /> <br />(55636) 2002 TX300 <br /> <700 km(9)<br /> <br />(28978) Ixion <br /> 500±100 km(10)<br /> <br />(55565) 2002 AW197 <br /> 700±100 km(11)<br /> <br />(4) Vesta <br /> 578×560×458 km(12)<br /> <br />(2) Pallas<br /> 570×525×500 km (13,14)<br /> <br />(10) Hygiea <br /> 500×400×350 km(15,16)<br /> <br /> <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[tfwthom]

Table 1: Overview of the planets in the Solar System as per 24 August 2006 if “Resolution 5 for GA-XXVI” is passed. <br /><br /> <br /><br />Object <br /> IAU definition <br /> IAU planet category <br /> Descriptive category <br /> Unofficial mean diameter estimate(1)<br /> <br />Mercury <br /> Planet <br /> <br /> Classical <br /> 4,879 km <br /> <br />Venus <br /> Planet <br /> <br /> Classical <br /> 12,104 km<br /> <br />Earth <br /> Planet <br /> <br /> Classical <br /> 12,746 km <br /> <br />Mars <br /> Planet <br /> <br /> Classical <br /> 6,780 km <br /> <br />Jupiter <br /> Planet <br /> <br /> Classical <br /> 138,346 km <br /> <br />Saturn <br /> Planet <br /> <br /> Classical <br /> 114,632 km <br /> <br />Uranus <br /> Planet <br /> <br /> Classical <br /> 50,532 km <br /> <br />Neptune <br /> Planet <br /> <br /> Classical <br /> 49,105 km <br /> <br />Ceres <br /> Planet <br /> <br /> Dwarf <br /> 952 km <br /> <br />Pluto <br /> Planet <br /> Pluton <br /> Dwarf <br /> 2306±20 km <br /> <br />Charon <br /> Planet <br /> Pluton <br /> Dwarf <br /> 1205±2 km <br /> <br />2003 UB313 <br /> Planet <br /> Pluton <br /> Dwarf <br /> 2400 ±100 km(2)<br /> <br /><br />Other objects that appear large enough so that their shape satisfies the definition of “planet” will be further considered on a case by case basis.<br /> <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[MeteorWayne]

Oh, that's where all those planets-to be came from.<br />Thanks TFWThom <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jschaef5]

So is this at the point where this is what it is most likely going to be or is there still a chance it will stay with the just the nine? I will no longer be able to remember the planet order by: My Very Educated Mother Just Served Us Nine Pizzas.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[tfwthom]

They usually follow what a working group decides, though there is a chance that they will not.<br /><br />It will be hard not to go along with this working group:<br /><br />Members of the Planet Definition Committee<br /><br /> <br /><br />Dr. Richard Binzel is Professor of Earth, Atmospheric and Planetary Science at MIT and a specialist in asteroids and outer solar system small bodies, and is also a well known and respected educator and science writer.<br /><br /> <br /><br />Dr. Andre Brahic is Professor at Universite Denis Diderot (Paris VII) and is Director of the Laboratory Gamma-gravitation of the Commissariat a l'Energie Atomique. He specializes in planetary rings, and has co-discovered the rings and arcs of Neptune. For the French-speaking public, Andre Brahic is one of the best known popularisers of science and astronomy, having authored a number of books.<br /><br /> <br /><br />Dr. Owen Gingerich [chair], Professor of Astronomy and History of Science Emeritus at the Harvard-Smithsonian Center for Astrophysics, is an esteemed historian of astronomy with a broad perspective, and a prize-winning educator.<br /><br /> <br /><br />Dava Sobel is the author of the very successful books Longitude, The Planets, and Galileo's Daughter. She has a solid background in, and knowledge of, the history of science, astronomy in particular.<br /><br /> <br /><br />Dr. Junichi Watanabe is an Associate Professor and also Director of the Outreach Division of NAOJ. He is a solar system astronomer and highly appreciated in Japan as interpreter and writer of astronomy for the public and students. He has strong connections with amateur astronomers, science editors, school teachers and journalists.<br /><br /> <br /><br />Dr. Iwan Williams, Queen Mary University of Londo, is an expert on the dynamics and physical properties of Solar System objects. He is the current President of IAU Division III (Planetary Systems Sciences).<br /><br /> <br /><br />Dr. Catherine Cesarsky, Director General of ESO and President-El <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[barrykirk]

Wait a minute.....<br /><br /><br />After reading the definition...<br /><br />Part B<br /><br />(b) is in orbit around a star, and is neither a star nor a satellite of a planet." <br /><br />Now wait a second they just called Charon a "Planet" when it is a satellite of Pluto....<br /><br /><br />

 

[MeteorWayne]

It's not a satellite. They both are satellites about their common center of mass, to be technical. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[barrykirk]

Pluto<br /><br />Mass: 1.27e22 kg<br />Diameter : 2274 km<br /><br />Charon<br /><br />Mass: 1.90e21 kg<br />Diameter : 1212 km<br /><br />Pluto - Charon Distance : 19,640 km <br /><br />Pluto is 6.7 times the mass of Charon so the Center of mass of the system should be about 6.7 times closer to Pluto.<br /><br />Center of Mass of system should be about 2900 Km from the center of Pluto.... Outside of the surface of Pluto... Your right it is a double planet.... but by that definition the earth's moon would also be a planet.<br /><br />So the new list would be<br /><br />1) Mercury<br />2) Venus<br />3) Earth<br />4) Moon ( Luna )<br />5) Mars<br />6) Ceres<br />7) Jupitar<br />8) Saturn<br />9) Uranus<br />10) Neptune<br />11) Pluto<br />12) Charon<br />13) 2003UB313<br /><br />Actually, didn't Isaac Asimov once write a short piece on the the double planet?

 

[MeteorWayne]

Wait a minute.<br />I am sure I have read the barycenter of the earth-moon system is well below the earth's surface. Am I wrong?<br />Time for some research! ;p <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[halcyondays]

It's due to that rather arbitrary difference (ie. the earth/moon barycentre is within the earth itself) that the Moon is not a planet, while Charon is a planet. Am I the only one that finds that somewhat specious ?

 

[djtt]

seems quite reasonable to me<br />its measurable which doesnt go for quite a few planet/ nonplanet arguments

 

[vogon13]

(just because I love throwing stuff like this out)<br /><br />Did anyone take note that Ceres and Pallas (or is it Juno?) are in a 1:1 resonance in their path around the sun?<br /><br /><br /><br /><img src="/images/icons/laugh.gif" /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[barrykirk]

I seem to remember reading a Isaac Asimov short non fiction piece on the Earth-Moon system where he described the Earth-Moon system as unique in the solar system.<br /><br />I don't remember the details, but I think it had something to do with the moon being more gravitationally linked to the sun than the earth or something like that.

 

[alokmohan]

I remenber reading it.We may lobby for the moon also.

 

[tfwthom]

http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html<br /><br />IAU 2006 General Assembly: Result of the IAU Resolution votes<br /><br />24. August 2006, Prague<br /><br /><br /><br />IAU Resolution: Definition of a Planet in the Solar System<br />Contemporary observations are changing our understanding of planetary systems, and it is important that our nomenclature for objects reflect our current understanding. This applies, in particular, to the designation 'planets'. The word 'planet' originally described 'wanderers' that were known only as moving lights in the sky. Recent discoveries lead us to create a new definition, which we can make using currently available scientific information.<br /><br />RESOLUTION 5A<br />The IAU therefore resolves that "planets" and other bodies in our Solar System be defined into three distinct categories in the following way:<br /><br />(1) A "planet"1 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.<br /><br />(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) shape2 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.<br /><br />(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies". <br /><br /><br /><br /><br />--------------------------------------------------------------------------------<br /><br />1The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.<br />2An IAU process will be established to assign borderline objects into either dwarf planet and other categ <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[alokmohan]

Now we have eight planets.

 

[MeteorWayne]

Despite considering the valid argumants for the 12+ planet original resolution, this has always made the most sense.<br />Since I really began to think about the issue a few years ago, I've been an eight planet guy. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[tfwthom]

I actually don't care, I just want to know what to call an object when doing public outreach. When I have shown Pluto in the past you can't tell anything about it anyway. (not unless you sketch it) So maybe I'll add a dwarf planet tour. <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>