posted August 16, 2006 04:26 PM              

Astronomers meet to define 'planet'

An artist's concept of 2003 UB313, an icy body that lies beyond the planet Neptune.

Tuesday, August 15, 2006; Posted: 5:29 p.m. EDT (21:29 GMT)

PRAGUE, Czech Republic (AP) -- Nearly 2,500 astronomers from 75 countries gathered in Prague Monday to come up with a universal definition of what qualifies as a planet and possibly decide whether Pluto should keep its planet status.

For decades, the solar system has consisted of nine planets, even as scientists debated whether Pluto really belonged. Then the recent discovery of an object larger and farther away than Pluto threatened to throw this slice of the cosmos into chaos.

Among the possibilities at the 12-day meeting of the International Astronomical Union in the Czech Republic capital: Subtract Pluto or christen one more planet, and possibly dozens more.

But the decision won't be an easy one. Scientists attending the conference are split over whether Pluto should be excluded from the list of planets, Pavel Suchan of the meeting's local organization committee said.

"So far it looks like a stalemate," Suchan said. "One half wants Pluto to remain a planet, the other half says Pluto is not worth being called a planet."

Participants hope to set scientific criteria for what qualifies as a planet. Should planets be grouped by location, size or another marker? If planets are defined by their size, should they be bigger than Pluto or another arbitrary size? The latter could expand the solar system to 23, 39 or even 53 planets.

The debate intensified last summer when astronomer Michael Brown of the California Institute of Technology announced the discovery of a celestial object larger than Pluto. Like Pluto, it is a member of the Kuiper Belt, a mysterious disc-shaped zone beyond Neptune containing thousands of comets and planetary objects. Brown nicknamed his find "Xena."

The Hubble Space Telescope measured the bright, rocky object officially known as 2003 UB313, at about 1,490 miles (2,384 kilometers) in diameter, roughly 70 miles (112 kilometers) longer than Pluto. At 9 billion miles (14 billion kilometers) from the sun, it is the farthest known object in the solar system.

The discovery stoked the planet debate that had been simmering since Pluto was spotted in 1930.

For years, Pluto's inclusion in the solar system has been controversial. Astronomers thought it was the same size as Earth, but later found it was smaller than Earth's moon. Pluto is also odd in other ways: With its elongated orbit and funky orbital plane, it acts more like other Kuiper Belt objects than traditional planets.

Some argue that if Pluto kept its crown, Xena should be the 10th planet by default -- it is, after all, bigger. Purists maintain that there are only eight traditional planets, and insist Pluto and Xena are poseurs.

Still others suggest a compromise that would divide planets into categories based on composition, similar to the way stars and galaxies are classified. Jupiter could be labeled a "gas giant planet," while Pluto and Xena could be "ice dwarf planets."

A decision on whether Pluto should be excluded or if "Xena" should be included on the list of planets will not be known before the end of the conference, Suchan said.

"We of course need the definition of a planet first."

posted August 16, 2006 04:32 PM              

By SETH BORENSTEIN , 08.16.2006, 03:12 PM

The idea that our nine-planet solar system may soon join the obsolete world of eight-track tapes and slide rules should send science teachers, textbook writers and toymakers back to the cosmic drawing board.

"Does it make our products obsolete?" asked Kim McLynn, spokeswoman for Illinois-based Learning Resources, which makes an inflatable solar system and a Planet Quest game. "Wow, a whole new universe."

Though not approved yet, the 76-year-old lineup of the solar system's planets would grow to 12 under a proposal by leading astronomers. Their recommendation will be decided by a vote of the International Astronomical Union on Aug. 24.

For people who make their living on the old Mercury-through-Pluto system, a change in the planets means quick but welcome revisions, no matter how costly.

"This is, of course, a huge headache for publishers," said Gilbert Sewall, director of the American Textbook Council, a New York-based research institute that follows educational textbooks. Last-minute changes are expensive, but won't break any publisher, he said.

For example, Pearson Prentice Hall has science texts for next year going before California's textbook approval board and will try to get the 12-planet revision in for the state officials to review, said Julia Osborne, the publisher's science editorial director.

"It's worth it because this is such an exciting thing," Osborne said. But 2006 textbooks are already at schools, she said, so for "most students this fall it will be out of date."

Because schools keep textbooks for five to 10 years, it will be about seven years before most school books have 12 planets in them, said Osborne and Sewall.

Pity Jack Horkheimer, director of the Miami Space Transit Planetarium and host of PBS' "Star Gazer" show. His very first book, a full-length cartoon guide to naked-eye astronomy, features an entire chapter on the solar system - the nine-planet version.

It won't be out for four more weeks - after the world's astronomers are likely to open the solar system doors to three new planets: Ceres, Charon, and one nicknamed Xena to be renamed later.

"My book is out-of-date before it even hits the bookstands," Horkheimer said. "It's kind of like buying a computer. By the time you get it out of the box and get it hooked up, it's already obsolete."

At the Adler Planetarium in Chicago, the main pavilion has a model of the solar system - the sun and nine planets (Earth is the size of a softball). The planetarium will likely have to add three new planets.

"They're pretty small," said astronomy director Geza Gyuk of the proposed new planets. "Maybe we can bring in a pingpong ball and that'll do the trick."

The Adler already has a planetary anachronism. When it opened 76 years ago, plaques had already been commissioned for just eight planets. Pluto was discovered a few months laterGyuk doesn't see the Adler adding plaques for Pluto or the three proposed planets because "we just don't have space."

For the several thousand planetariums around the world, this is more exciting than difficult, said Susan Reynolds Button, president-elect of the International Planetarium Society.

"It's not a problem," Reynolds Button said. "We already have the visuals. We already have the equipment to do it. It's just a matter of presenting new data."

Reynolds Button, who used to take planetarium shows to schools, said the addition of three new planets "is a real nice juicy topic to get kids excited about."

Dan Reidy, a sixth-grade science teacher in Moultonborough, N.H., was sitting in his classroom preparing for the new school year and gazing at his model of the solar system. He usually asks his students, "What's wrong with this picture?" The correct answer is that the planet sizes and their distances from the sun are all out of proportion.

If the planet lineup changes, there will be something else wrong with his model.

Reidy will also have to figure out where to place the new planets on a large parachute-cloth solar system map that demonstrates proper size and scale, but he said it was exciting.

The race to change solar system toys more permanently is already on.

Discovery Channel Store spokeswoman Pamela Rucker predicted new 12-planet toys could be in stores in time for the Christmas season.

"We're already starting to work on 12 planets," said McLynn of Learning Resources.

posted August 16, 2006 04:46 PM              

The International Astronomical Union is debating a plan to establish that our solar system has 12 planets.

Wednesday, August 16, 2006 Posted: 1408 GMT (2208 HKT)

PRAGUE, Czech Republic (AP) -- Our solar system would have 12 planets instead of nine under a proposed "Big Bang" expansion by leading astronomers, changing what billions of schoolchildren are taught about their corner of the cosmos.

Much-maligned Pluto would remain a planet -- and its largest moon plus two other heavenly bodies would join Earth's neighborhood -- under a draft resolution to be formally presented Wednesday to the International Astronomical Union, the arbiter of what is and is not a planet.

"Yes, Virginia, Pluto is a planet," quipped Richard Binzel, a professor of planetary science at the Massachusetts Institute of Technology.

The proposal could change, however: Binzel and the other nearly 2,500 astronomers from 75 nations meeting in Prague to hammer out a universal definition of a planet will hold two brainstorming sessions before they vote on the resolution next week. But the draft comes from the IAU's executive committee, which only submits recommendations likely to get two-thirds approval from the group.

Besides reaffirming the status of puny Pluto -- whose detractors insist should not be a planet at all -- the new lineup would include 2003 UB313, the farthest-known object in the solar system and nicknamed Xena; Pluto's largest moon, Charon; and the asteroid Ceres, which was a planet in the 1800s before it was demoted.

The panel also proposed a new category of planets called "plutons," referring to Pluto-like objects that reside in the Kuiper Belt, a mysterious, disc-shaped zone beyond Neptune containing thousands of comets and planetary objects. Pluto itself and two of the potential newcomers -- Charon and 2003 UB313 -- would be plutons.

Astronomers also were being asked to get rid of the term "minor planets," which long has been used to collectively describe asteroids, comets and other non-planetary objects. Instead, those would become collectively known as "small solar system bodies."

If the resolution is approved, the 12 planets in our solar system listed in order of their proximity to the sun would be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon, and the provisionally named 2003 UB313. Its discoverer, Michael Brown of the California Institute of Technology, nicknamed it Xena after the warrior princess of TV fame, but it likely would be rechristened something else later, the panel said.

The galactic shift would force publishers to update encyclopedias and school textbooks, and elementary school teachers to rejigger the planet mobiles hanging from classroom ceilings. Far outside the realm of science, astrologers accustomed to making predictions based on the classic nine might have to tweak their formulas.

Even if the list of planets is officially lengthened when astronomers vote on Aug. 24, it is not likely to stay that way for long: The IAU has a "watchlist" of at least a dozen other potential candidates that could become planets once more is known about their sizes and orbits.

"The solar system is a middle-aged star, and like all middle-aged things, its waistline is expanding," said Jack Horkheimer, director of the Miami Space Transit Planetarium in the United States and host of Public Broadcasting's Stargazer television show.

Opponents of Pluto, which was named a planet in 1930, still might spoil for a fight. Earth's moon is larger; so is 2003 UB313 (Xena), about 70 miles (113 kilometers) wider.

But the IAU said Pluto meets its proposed new definition of a planet: any round object larger than 800 kilometers (nearly 500 miles) in diameter that orbits the sun and has a mass roughly one-12,000th that of Earth. Moons and asteroids will make the grade if they meet those basic tests.

Roundness is key, experts said, because it indicates an object has enough self-gravity to pull itself into a spherical shape. Yet Earth's moon would not qualify because the two bodies' common center of gravity lies below the surface of the Earth.

"There are as many opinions about Pluto as there are astronomers," Binzel said. "But Pluto has gravity on its side. By the physics of our proposed definition, Pluto makes it by a long shot."

IAU President Ronald D. Ekers said the draft definition, two years in the making, was an attempt to reach a cosmic consensus and end decades of quarreling. "We don't want an American version, a European version and a Japanese version" of what constitutes a planet, he said.

Neil deGrasse Tyson, director of the Hayden Planetarium at New York's American Museum of Natural History -- miscast as a "Pluto-hater," he contends, merely because Pluto was excluded from a planetarium solar system exhibit -- said the new guidelines would clear up the fuzzier aspects of the Milky Way.

"For the first time since ancient Greece, we have an unambiguous definition," he said. "Now, when an object is debated as a possible planet, the answer can be swift and clear."

posted August 24, 2006 06:35 PM              

INTERNATIONAL ASTRONOMICAL UNION
Astronomers have agreed only to recognize eight "classical" planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Aug. 24, 2006. 02:21 PM
ASSOCIATED PRESS

PRAGUE, Czech Republic — Leading astronomers declared today that Pluto was no longer a planet under historic new guidelines that downsize the solar system from nine planets to eight.
After a tumultuous week of clashing over the essence of the cosmos, the International Astronomical Union stripped Pluto of the planetary status it has held since its discovery in 1930. The new definition of what is — and isn’t — a planet fills a centuries-old black hole for scientists who have laboured since Copernicus without one.

The historic vote officially shrinks Earth’s neighbourhood from the traditional nine planets to eight. But the scientists made clear they’re as sentimental as anyone about the ninth rock from the sun.

Jocelyn Bell Burnell — a specialist in neutron stars from Northern Ireland who oversaw the proceedings in Prague — urged those who might be “quite disappointed” to look on the bright side.

“It could be argued that we are creating an umbrella called `planet’ under which the dwarf planets exist,” she said, drawing laughter by waving a stuffed Pluto of Walt Disney fame beneath a real umbrella. Later, she hugged the doll as she stood at the dais.

“Many more Plutos wait to be discovered,” added Richard Binzel, a professor of planetary science at the Massachusetts Institute of Technology.

The decision by the international group spells out the basic tests that celestial objects will have to meet before they can be considered for admission to the elite cosmic club.

For now, membership will be restricted to the eight “classical” planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Much-maligned Pluto — named for the god of the underworld — doesn’t make the grade under the new rules for a planet: “a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a .x .x . nearly round shape, and has cleared the neighbourhood around its orbit.”

Pluto is automatically disqualified because its oblong orbit overlaps with Neptune’s.

Instead, it will be reclassified in a new category of “dwarf planets,” similar to what long have been termed “minor planets.” The definition also lays out a third class of lesser objects that orbit the sun — “small solar system bodies,” a term that will apply to numerous asteroids, comets and other natural satellites.

Experts said there could be dozens of dwarf planets catalogued across the solar system in the next few years — handing the world’s school teachers a challenge.

Neil Crumpton, a science teacher at Mountfitchet High School in Stansted Mountfitchet, north of London, called the announcement “very exciting.”

“To be honest, this has been brewing for a while. Pluto has always been a bone of contention among astronomers because of the odd way it orbits the sun,” Crumpton said. “For a start, we’ll have to change all the mnemonics we use to teach children the lineup of the planets. But Pluto has not disappeared and it doesn’t hurt children to know about it.”

NASA said today that Pluto’s demotion would not affect its $700-million New Horizons spacecraft mission, which earlier this year began a 9 1/2-year journey to the oddball object to unearth more of its secrets.

“We will continue pursuing exploration of the most scientifically interesting objects in the solar system, regardless of how they are categorized,” Paul Hertz, chief scientist for the science mission directorate, said in a statement.

The decision at a conference of 2,500 astronomers from 75 countries was a dramatic shift from just a week ago, when the group’s leaders floated a proposal that would have reaffirmed Pluto’s planetary status and made planets of its largest moon and two other objects.

That plan proved highly unpopular, splitting astronomers into factions and triggering days of sometimes combative debate that led to Pluto’s undoing. In the end, only about 300 astronomers cast ballots.

Now, two of the objects that at one point were cruising toward possible full-fledged planethood will join Pluto as dwarfs: the asteroid Ceres, which was a planet in the 1800s before it got demoted, and 2003 UB313, an icy object slightly larger than Pluto whose discoverer, Michael Brown of the California Institute of Technology, has nicknamed “Xena.”

Charon, the largest of Pluto’s three moons, is no longer under consideration for any special designation. ation.

posted August 24, 2006 06:42 PM              

By Martin Roberts

TORONTO (Reuters) - Scientists may have demoted Pluto to the rank of a "dwarf planet" on Thursday but astrologers foretell no major changes in the way they read the heavens because of the move.

Russell Grant, a British astrologer and best-selling author, said Pluto's planetary demotion was not a surprise after years of discussion and he would not change the charts he uses for his clients or millions of visitors to his Web site.

"I personally am shaken not stirred," Grant said in a telephone interview from Britain. "It's very interesting that Pluto's been downgraded in a planetary sense because he could never be downgraded in a mythological sense.

"I will continue to use Pluto because he gives me the ability to look into people's charts and see where they're coming from psychologically," he said.

Grant noted that astrologers had long used non-planets, such as Earth's moon. He also charts several asteroids, which are inside the solar system but much smaller than planets.

Astrology, the belief that the relative position of celestial bodies can help in the understanding of human affairs and earthly events, arose several millenniums ago. Although hugely popular, it is quite separate from the modern scientific study of astronomy.

"Astronomers have had several cases in the past where they've made changes in the objects used by astrologers," said Lee Lehman, academic dean of Kepler College in Seattle, the only institute in the Western Hemisphere to award degrees in astrological studies.

Lehman said it took several decades for astrologers to reach a consensus on the relevance of Pluto after its discovery in 1930.

One of the reasons astronomers unseated Pluto was that technological advances made them aware it was actually smaller than a body discovered in 2003 and nicknamed Xena, after the warrior princess in the television show.

"There is now quite a bit of interest now in the astrological community about Xena," Lehman said, without being able to predict whether the body would have a significant impact on astrology.

Grant said Xena had limited use as its position meant it would currently only affect people whose sun signs were in Pisces and Aries, just two of 12 constellations in the zodiac, a celestial band observed by astrologers.

posted August 24, 2006 09:48 PM              

It's as you pointed out on the Astrology thread on this subject ,DD, the moon is not a planet either and it is a large part of astrology.