Latest Update 11/23/06
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8/24/06
IAU 2006 General Assembly: Result of the IAU Resolution votesRESOLUTIONS
Resolution 5A is the principal definition for the IAU usage of "planet" and related terms.
Resolution 6A creates for IAU usage a new class of objects, for which Pluto is the prototype. The IAU will set up a process to name these objects.
IAU Resolution: Definition of a Planet in the Solar System
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.
RESOLUTION 5A
The IAU therefore resolves that "planets" and other bodies in our Solar System be defined into three distinct categories in the following way:
(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.
(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 (2) , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects (3) except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".
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(1) The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
(2) An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
(3) These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
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IAU Resolution: Pluto
RESOLUTION 6A
The IAU further resolves:
Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1
For more information, click here.
11/23/06
Why Planets Will Never Be Defined
Before the dust even settled after the Great Pluto War at the International Astronomical Union (IAU)'s General Assembly in Prague, one thing became clear: There will never be an accepted scientific definition for the term "planet." Rather than crafting an acceptable definition, the IAU alienated members, put the group's authority in jeopardy and fueled schisms among astronomers on theoretical grounds and even nationality. And the whole affair was scientifically pointless, many astronomers say. The controversial planet-definition resolution, passed Aug. 24 in a vote of just 424 IAU members, will not stand as worded. Some 300 astronomers have pledged not to use it, and many others say it must be redone to eliminate contradictions. It will be reworked, at the least, and possibly overturned at the 2009 IAU General Assembly in Rio de Janeiro, Brazil.
To read the story, click here.10/23/06
Teachers See Educational Value in Pluto Demotion
Pluto may be no more than a distant, icy rock in the minds of astronomers who stripped it of planethood, but its downgrade to a "dwarf planet'' has created a teachable moment in classrooms nationwide. So what if museums have to adjust their exhibits and publishers update their textbooks? That's just science, many teachers said Friday at a regional meeting of the National Science Teachers Association.
To read more, click here.9/14/06
Interview with the IAU President on Pluto's Demotion
Last month, Catherine Cesarsky became the president of the International Astronomical Union (IAU). Cesarsky, the first woman to hold this prestigious position, started her presidency at a time when many scientists are questioning IAU's recent decision to strip Pluto of its planetary status based on a vote of just 424 members at a meeting in Prague. Cesarsky served as the director general of the European Southern Observatory since 1999 and is famed for her research work in central areas of modern astrophysics. She also led the design and construction of the ISOCAM camera onboard the Infrared Space Observatory (ISO) of the European Space Agency (ESA). In an email interview with SPACE.com, Cesarsky discusses her thoughts on the role of the IAU as a governing body and the split of the scientific community on the new definition and the way the process was handled, effectively excluding 10,000 professional astronomers around the globe.
To read the interview, click here.9/14/06
Pluto is Now Just a Number: 134340
Pluto has been given a new name to reflect its new status as a dwarf planet. On Sept. 7, the former 9th planet was assigned the asteroid number 134340 by the Minor Planet Center (MPC), the official organization responsible for collecting data about asteroids and comets in our solar system. The move reinforces the International Astronomical Union's (IAU) recent decision to strip Pluto of its planethood and places it in the same category as other small solar-system bodies with accurately known orbits.
To read the story, click here.9/10/06
Planetary Politics: Protecting Pluto
When the IAU voted to demote Pluto from the pantheon of planets, they generated a storm of protest from the public. Reclassifying Pluto as a "dwarf planet" did little to stem the criticism. From kindergarteners to grandparents, people love Pluto. Why do they love this tiny, icy globe? I'm not entirely sure, but it probably has a lot to do with third-grade science fair projects and an animated dog.
To read more, click here.9/7/06
Clyde Tombaugh's Family Joins Protest of Pluto's Downgrade
Defenders of Pluto as a planet rallied at New Mexico State University last week, joined by the wife and son of Pluto's discoverer, Clyde Tombaugh. The Sept. 1 gathering in Las Cruces was spurred by last month's decision by the International Astronomical Union (IAU) to reclassify Pluto as a "dwarf planet" and, by the new definition, not really a planet at all. The message from the protestors: Don't rewrite the textbooks yet as the debate's not over.
To read the article, click here.9/7/06
Pluto supporters to IAU: The debate's not over
Friends and colleagues of the late Clyde Tombaugh, discoverer of Pluto, had this to say Friday about the International Astronomical Union's decision to reclassify Pluto as a "dwarf planet": Don't rewrite the textbooks yet. "Why not? Because the debate is not over," New Mexico State University astronomer Bernie McNamara told a high-spirited group of Pluto supporters outside the university's Zuhl Library.
To read the story, click here.9/2/06
Planetary Scientists and Astronomers Oppose New Planet Definition
On August 24th, a session of the International Astronomical Union (IAU), meeting in Prague, passed a resolution re-defining the planets of our solar system. Just after the August 24th vote, serious technical and pedagogical flaws were pointed out in the IAU's definition of planets. As a consequence of these flaws, a grass roots petition stating, "We, as planetary scientists and astronomers, do not agree with the IAU's definition of a planet, nor will we use it. A better definition is needed "was placed on the web at http://www.ipetitions.com/petition/planetprotest and circulated by email to a small fraction of the world's astronomical research community.
To read the news, click here.9/2/06
Pluto: Down But Maybe Not Out
If you did not like Pluto's demotion, don't give up hope. Arguments over the newly approved definition for "planet" are likely to continue at least until 2009, and astronomers say there is much that remains to be clarified and refined. While it is entirely unclear if the definition could ever be altered enough to reinstate Pluto as a planet, astronomers clearly expect some changes. In a statement today, the largest group of planetary scientists in the world offered lukewarm support for the definition, which was adopted last week by a vote of just a few hundred astronomers at the International Astronomical Union (IAU) General Assembly meeting in Prague.
To read the article, click here.8/26/06
Pluto: Solar System's Loss is Collectors' Gain
Text books aside, there are hundreds if not thousands of products that were or are now on the market that include Pluto as the ninth planet of the solar system. On Thursday, 424 astronomers voted to strip the small body of its planethood. Instead, Pluto is now categorized a "dwarf planet," one of hundreds that might be identified in the coming months and years. In essence, the International Astronomical Union decided that when it came to planets, eight really was enough. This may be bad news for Pluto fans, but for collectors, it presents an opportunity.
To read the story, click here.8/26/06
New Planet Definition Leaves Scientific Loose Ends
The controversial vote today that reduced our solar system's planet tally to eight has left a series of loose scientific ends in its wake. Not only does it leave NASA with a robotic mission en route to an "unplanet," astronomers are wondering what names will be given to all the little round objects in the outer solar system, decisions that will force changes in textbooks and curricula. But it's all for the good, many astronomers say.
To read more, click here.8/24/06
Honey, I Shrunk the Solar System
If you woke up Thursday morning and sensed something was different about the world around you, you're absolutely right. Pluto is no longer a planet. The International Astronomical Union, wrapping up its meeting in Prague, Czech Republic, has resolved one of the most hotly-debated topics in the cosmos by approving a specific definition that gives our solar system eight planets, instead of the nine most of us grew up memorizing.
To read the news, click here.
Hi there,
I just wanted to chip in and let it be known that I think the IAU's demotion of Pluto sucks. Not because it overturns tradition, but because it is cynical, atrocious science.
I have serious problems with their clause that a planet must have cleared the space in its orbit. By that definition, Earth would not qualify as a planet. I know enough about astronomy to know that there thousands of Near Earth Objects that are relatively close to the Earth, with more being found every year. The Earth itself gets
bombarded by thousands of meteors each year, many of which can be seen from the ground as they burn up in the atmosphere.
And what if you go back a couple of billion years? The rocky body planets of the solar system would have long since formed and coalesced, but the solar system would have been a much dirtier place. The craters on the moon give ample evidence just how unswept the orbit around Earth was back then. Yet, both the Earth and moon had clearly formed as rocky planets, but suddenly, we are to believe that Earth wouldn't qualify as a planet because of the IAU? This simple thought experiment shows just how atrocious the new definition is.
I can only conclude the only reason the orbit clause was added was to demote Pluto. It seems that Pluto qualifies as a planet in every other way, so the orbit clause was added cynically to disqualify it, just to avoid the potential problem of finding more Pluto-like objects in the future. Except, what happens if astronomer find a Mercury-size or Venus-size object beyond the orbit of Pluto? BAAAAD science is at work here, and it stinks to the heavens.
Sadly, it seems that the IAU has also demoted Earth and quite possibly a number of the other planets, too. What the IAU did last week was not science, it was politics, pure and simple. I mean, when less than 10% of the IAU's members were present to vote, doesn't that violate some universally accepted ideas of a quorum? Even if it wasn't against the rules, doesn't the vote violate all sense of common decency and professional respect?
So either the IAU's vote be overturned in a very dramatic fashion for its act of midnight democracy, or astronomers should form a new international union to supplant it. The new definiton cannot stand.
Just my $0.02 worth.
Paul Lee