IAU made a change to the "Astronomical Unit"...now 149,597,870,700 meters

"Basic solar system measure redefined"

September 17th, 2012

SPACEDAILY

Astronomers meeting in Beijing say they've agreed on a new definition of the fundamental unit of distance between objects in the solar system.

The "astronomical unit," defined as the distance between the sun and the Earth, is now set at exactly 149,597,870,700 meters (163,602,220,800.53 yards or 92,955,807.27 miles), the meeting of the International Astronomical Union declared.

That's 9 meters, or about 30 feet, more than the previously agreed distance, which was based on the average distance between Earth and the sun and was also tied to the mass of the sun.

But the sun is constantly losing mass as it radiates energy, which technically changes the value of the AU over time, astronomers said.

"The old definition was good when we were not able to measure distance precisely in the solar system," Sergei Klioner of the Technical University of Dresden, Germany, who has been calling for the change since 2005, told NewScientist.com.

But scientists can now make precise measurements of astronomical distances using lasers and space probes.

"I've been teaching celestial mechanics for 20 years and it was always a pain to explain the old definition," Klioner said. "It was clear that it was unnecessarily complicated."

Laurel Kornfeld has a legitimate request regarding astronomical nomenclature

Laurel has for a long time been an advocate for Pluto and in general questioned substantiation of some of the basic definitions adopted and promoted by the IAU [International Astronomical Union]. Here is her current letter to the IAU.

August 22, 2012

Dear Dr. Williams, Members of the IAU Executive Committee, Members of the

Secretariat, Members of the Working Group on Planetary System Nomenclature, Members of the Working Group on Small Bodies Nomenclature, and Delegates to the 28th IAU General Assembly,

For the second time, I am writing to respectfully request the General Assembly officially reopen the planet definition issue in order to address ongoing questions and controversy that resulted from the 2006 planet definition vote as well as to incorporate new data on objects in our own solar system and on exoplanets into a more broad, inclusive, and comprehensive understanding that streamlines the spectrum of sub-stellar bodies ranging from tiny asteroids and comets to the largest sub-brown dwarfs in this and in all stellar systems in the universe.

As I did in 2009, I ask specifically that you reconsider and add Resolution 5b from 2006, which would establish “planets” as a broad, umbrella category under which both classical and dwarf planets would be included; that the definition be expanded to include objects that orbit a star or are free-floating, to accommodate exoplanets and rogue planets; and that electronic voting be enabled to allow IAU members who are unable to physically attend General Assemblies to vote remotely.

In the six years since the 2006 vote, there have been significant discoveries in both our solar system and others that call into question the utility of the planet definition then adopted. Many exoplanets since discovered would not fit the planet definition adopted then even if it were expanded to include objects other than those that orbit the Sun. Astronomers have discovered exoplanet systems in which two planets share the same orbit; systems with two giant planets in 3:2 resonances; systems with as many as six planets all orbiting within a distance from their star comparable to Mercury’s orbit; planets that orbit their stars backward; and planets that formed directly from stellar nebulae the way stars do. Many exoplanets discovered have extremely elliptical, even comet-like, orbits.

In our solar system, the Dawn mission has revealed Vesta, which is not quite in hydrostatic equilibrium, to be far more like a terrestrial planet than like an asteroid. Vesta turns out to be a complex, geologically layered body with an iron core that formed in a process similar to the way terrestrial planets like Earth did. Dawn’s revelations have led some astronomers to question whether Vesta should be considered the solar system’s “smallest terrestrial planet. Vesta is not a simple ball of rock. This is a world with a rich geochemical history. It has quite a story to tell,” according to Dawn Principal Investigator Dr. Chris Russell.

As members of the IAU are well aware, Dawn is now departing Vesta and heading for Ceres, which it will study in similar detail.

The initial reason that prompted the 2006 General Assembly to determine a need for defining the term “planet” was the discovery of Eris, which was at the time believed to be larger than Pluto. However, in November 2010, when Eris occulted a star, a team of astronomers led by Dr. Bruno Sicardy determined that Eris is smaller than previously believed, marginally smaller than Pluto though about 27 percent more massive. This is significant because it calls into question the initial “need” for a definition since this “need” was based on erroneous information.

I am troubled by what appears to be an inflexible stand by the IAU, a determination to never reopen the planet definition discussion at any General Assembly, even into the indefinite future. This makes absolutely no sense. The 2006 discussion was based on new data discovered about Eris and the Kuiper Belt. Now, in 2012, we once again have more new data on bodies in this and other solar systems. Three years from now, we will have even more data on small planetary bodies via the Dawn mission to Ceres and the New Horizons mission to Pluto.

How can the IAU justify not reopening this discussion in light of all this new data? If this year’s General Assembly is determined to not take up the discussion, why not commit to putting it on the agenda for 2015? That would be an ideal time to take up the planet question again, as there will likely be a host of new information from the Dawn and New Horizons missions on two of the objects directly at the center of this debate.

As I did in 2009, I emphasize that this request is not about Pluto; it is about the need for a more useful, clear definition that encompasses both orbital dynamics and planetary geophysics, one that covers both our solar system and others.

The IAU considers communicating astronomy with the public as one of its essential tasks. I remind the organization that communication is a two-way street. Members of the public, astronomy enthusiasts, and amateur astronomers have consistently communicated dissatisfaction with the 2006 planet definition resolution. Isn’t it time the IAU hear them and respectfully respond to their concerns instead of ignoring and disenfranchising them?

Planetary science is constantly evolving with new discoveries, and in light of this, it makes sense that definitions will need to be updated and refined continuously. The 2006 vote was a first attempt at a definition, but it should not be considered a final one. This is not religion, where an authoritative body speaks once for all eternity, issuing a decree that can never be changed. By reopening the planet definition discussion, the IAU will affirm its relevance and flexibility through willingness to constantly reconsider previous decisions when new data call those decisions into question.

However, if the IAU continues to dig in its heals and refuse to even consider a new discussion on planet definition, the organization risks being viewed as emotional, bureaucratic, and dogmatic, and will become increasingly irrelevant as an authoritative body on the science of astronomy. At that point, other groups and individuals will very likely fill the void and take up the issue on their own, to the point that the matter may fall completely outside the influence of the IAU.

In order to further respectful two-way communication with the public, I urge the IAU to actively seek input on important issues such as this one from a broader population, including professional astronomers who are not IAU members, amateur astronomers and groups representing them, and astronomy students at all levels.

Regardless of the fact that no action on the planet classification issue has been planned for this General Assembly, I implore the IAU’s leadership, delegates to the GA, and members to do what needs to be done, to show courage and sensitivity to both scientists and lay people by admitting the planet definition issue remains unresolved and by adding a provision to this year’s GA reopening the planet definition discussion, or at least committing to putting it on the agenda of the 29th GA in 2015.

More specifically, I also ask that the Resolutions Committee place a resolution on the General Assembly floor for a vote on August 31, 2012, to officially reconsider resolution 5b of 2006, which if passed would establish dwarf planets as a subclass of planets. I also ask that a second resolution be put to the GA floor to include exoplanets in all further planet definition discussions. Finally, I ask that a resolution allowing for electronic voting be adopted before any other resolutions are considered to allow the IAU’s full membership to vote on all relevant issues, a provision badly needed in these difficult economic times when so many cannot afford the expense of travel and lodging to attend the GA in person.

Sincerely,

Laurel E. Kornfeld

Highland Park, NJ, USA

Writer, amateur astronomer, astronomy student and blogger

http://laurelsplutoblog.blogspot.com

http://laurele.livejournal.com

Pluto fizzled at IAU's Rio meeting

The IAU's Rio meeting never discussed the sensitive issue of Pluto's status.

"Pluto still not a planet after astronomy meeting"

by

Dan Vergano

August 13th, 2009

USA Today

An international astronomy meeting ended Thursday in Rio de Janeiro, and Pluto is still not a planet. The closing ceremonies of the 2009 International Astronomical Union (IAU) concluded with nary a peep about the planetary brouhaha that saw walk-outs and table-banging three years ago at the venerable astronomer's assembly, in Prague.

"None of that stuff at all came up," said IAU spokesman Lars Lindberg Christensen, speaking from a taxi speeding away from the meeting for one of Rio's restaurants. "I believe people still disagree, but the focus was really on science at the meeting."

In 2006, the IAU meeting assembly demoted Pluto into a "dwarf planet" (sometimes called a "plutoid") because it has failed to have "cleared the neighborhood around its orbit," in the words of the assembly's resolution. Pluto only weighs 0.07 as much as the rest of the objects in its orbit, which includes "Kuiper Belt" comets and Neptune, an ice giant planet. Earth, in contrast, weighs 1.7 million times more than the remaining objects in its orbit, asteroids and the moon, making it a planet, according to the just-released Pluto Confidential: An Insider Account of the Ongoing Battles Over the Status of Pluto, by astronomers Steve Maran and Laurence Marschall.

The two authors split on whether Pluto is a planet, with Maran arguing for the demoted world. "Pluto is still the people's planet and, if anything, more popular as an underdog than ever before," Maran writes.

"I believe that the IAU had no interest in revisiting the question of Pluto this year. The vocal disagreements that occurred at the General Assembly in 2006 embarrassed the organization. The decision made then, whether we like it or not, solved the IAU’s practical problem, by specifying how objects in the Kuiper Belt will be classified, for purpose of assigning names to them, an IAU responsibility. They name planets according to one practice and dwarf planets and asteroids in another way," Maran says. "Meanwhile, astronomers are generally agreed that the 2006 IAU planet definition is not helpful in our scientific work, and will fall into disuse. That may not bring Pluto back, however."

Indeed, the IAU meeting ended with a resolution to develop more astronomical resources for poorer nations, instead of a fight over Pluto. But the battle isn't likely over. "I expect people will still argue, and that's probably a good thing for science," Lindberg says.

Pluto's status in IAU Rio meeting?

The subject may never come up.

"Pluto's planetary plea not in scientists' scope"

Formerly known as a planet, heavenly body's demotion is likely to stick at new meeting

by

Eric Berger

August 2nd, 2009

Houston Chronicle

When they convene Monday in Rio de Janeiro, the grand pooh-bahs of astronomy appear unlikely to revisit their decision from three years ago to demote Pluto, the heavenly body formerly known as the solar system's ninth planet.

The ostracism of Pluto comes despite a slow boil among many U.S. astronomers seething ever since the International Astronomical Union's declassification, as it was the only planet ever found by an American astronomer, Clyde Tombaugh.

"My guess is that the officers of the IAU are going to do their level best to keep Pluto's head from rising at this meeting," said astronomer Stephen Maran , co-author of a new book called Pluto Confidential.

"I think they were very embarrassed about what happened at the last general assembly."

When the IAU general assembly last met three years ago, the world watched as a majority of just 424 total votes were cast to put Pluto in what astronomers felt was its rightful place.

Not only did the scientists at the Prague-based meeting vote to classify Pluto as a "dwarf planet," Maran said, but with perhaps a tinge of anti-Americanism amid the Iraq War they also took the punitive step of ruling that dwarf planets themselves were not planets.

Within weeks of its demotion, Pluto was given the numerical designation 134340 by the IAU's Minor Planet Center, which largely catalogs asteroids. Pluto was now just a number.

The swift and unexpected demotion of Pluto startled the American public, which protested through state legislature resolutions, petitions signed by astronomers to restore Pluto to planethood, and even a song by the band SubPlot A dubbed Pluto Rocks.

Despite all of this, with the first opportunity to finally change Pluto's official status, it's nowhere to be found on the IAU agenda.

"No resolution was submitted in the past months, so it is unlikely that the Pluto issue, or any other solar system naming matters, will come before the General Assembly," said Robert Williams , a Baltimore-based astronomer who is the IAU's president-elect.

So with no revision to Pluto's status is the former planet's demotion officially a fait accompli?

Not likely, said Mark Sykes, director of the Planetary Science Institute in Tuscon, Ariz.

"The IAU executive committee does not want to address it," Sykes said. "They put out their encyclical, and they're basically done with it. But does the IAU dictate thought? No, they're not the holy mother church. There are a lot of scientists who will simply ignore what they have done and continue to refer to and write about Pluto as a planet."

Celestial evidence

Sykes said he believes evidence will come out within the next decade that will force the IAU to reverse its decision on Pluto.

Two separate probes, the Dawn mission to the large asteroid Ceres and the New Horizons probe to Pluto, should reach their respective targets in the year 2015.

The IAU definition essentially treats dwarf planets such as Ceres and Pluto as innate hunks of rock, Sykes said. But both of these bodies have atmospheres, and Sykes believes the probes will also find evidence of geological activity. Ceres might even have a sub-surface ocean.

"I think we're going to find that these planets are much more like the Earth than Earth is like Jupiter," he said.

Not all American astronomers agree. Foremost among Pluto's detractors is Neil deGrasse Tyson , who as director of the Hayden Planetarium at the American Museum of Natural History in New York City in 2000 omitted Pluto from an exhibit of the planets.

At the Houston Museum of Natural Science, Pluto remains entrenched in an outdoor diagram of the planets, with a plaque that still lists it as a planet.

"We have no plans to remove the object since it's still there in the real solar system," said Carolyn Sumners , the museum's director of astronomy. "Since changing plaques is expensive and Pluto's status is still in flux, we decided to leave the plaque as it is and see if the astronomical community can reach a more permanent consensus."

Type Pluto in the search engine for more material.