Planet Pluto Gets The Boot :sadwave:

Interesting, never stop finding new.

I remember Pluto was added not too long ago now remove from number of planets.
 
Here we go again... changing history!

I remember back then when we only had 4 food groups. Now, we have 5 food groups.

Before, we had 9 planets. Now, we have 8. Ugh!
 
Here's a picture that compares the largest of the small outer solar system objects with some large main belt asteroids, Mercury, Earth and its Moon.

Comparison of the largest TNOs

Here's a picture comparing Pluto to the largest moons in the solar system. Earth's Moon, Jupiter's Io, Europa, Ganymede and Callisto, Saturn's Titan and Neptune's Triton are all larger than Pluto.

Pluto's size compared with the largest moons

This is a picture like the above, but includes Mercury and Uranus' Titania. Titania is Uranus' largest moon and the one in the picture that Pluto beats.

The Largest Moons and Smallest Planets

Ceres and some other large asteroids were considered planets for decades until the 1850s when they discovered a lot more asteroids. Now Pluto, Ceres and 2003 UB313 are dwarf planets and there is a list of other objects that could be dwarf planets.

The New Horizons spacecraft will get a Jupiter gravity assist next year and reach the Pluto system in 2015. The Dawn spacecraft will be launched next year, get a Mars gravity assist in 2009 and reach Vesta in 2011 and Ceres in 2015.

Vesta is on the list of possible dwarf planets. It's not a sphere, but being a sphere is not required for hydrostatic equilibrium because it's a blance between outwards and inwards forces. Objects like Saturn and 2003 EL61 are oblate because of their rapid rotation, but Saturn is in hydrostatic equilbrium because its shape results from a balance between gravity and the outward force due to rotation. 2003 EL61 could be in this state too so it's on the list of possible dwarf planets. For smaller objects, they are not in hydrostatic equilbrium because rigid body forces prevent a balance from happening, allowing the material to keep irregular shapes. The point at which this happens for icy objects is lower than for rocky ones because ice can flow and deform over time better than rock.

The reason Saturn is a planet and Vesta and 2003 EL61 could only be dwarf planets is because the latter two did not remove other objects of similar sizes from their neighborhood. There are great distances between the orbits of Saturn and those of Jupiter and Uranus.
 
Pluto demotion irks NASA scientist

SAN ANTONIO, Aug. 25 (UPI) -- A NASA scientist in San Antonio, Texas, is criticizing the International Astronomical Union for voting to remove Pluto from the solar system's list of planets.

Alan Stern at the Southwest Research Institute called the move by the IAU's General Assembly sloppy science and said it would never pass peer review, the BBC reports.

The official naming body for astronomy since 1919, the IAU approved a definition of a planet Thursday that demoted Pluto to the category of dwarf planet.

Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune.

"Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets," says Stern. "It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups.'"

Stern, who is the lead scientist on NASA's robotic mission to Pluto, called the IAU ruling embarrassing.
 
starrygaze said:
Pluto demotion irks NASA scientist

SAN ANTONIO, Aug. 25 (UPI) -- A NASA scientist in San Antonio, Texas, is criticizing the International Astronomical Union for voting to remove Pluto from the solar system's list of planets.

Alan Stern at the Southwest Research Institute called the move by the IAU's General Assembly sloppy science and said it would never pass peer review, the BBC reports.

The official naming body for astronomy since 1919, the IAU approved a definition of a planet Thursday that demoted Pluto to the category of dwarf planet.

Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune.

"Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets," says Stern. "It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups.'"

Stern, who is the lead scientist on NASA's robotic mission to Pluto, called the IAU ruling embarrassing.
Click to expand...

Alan Stern is the principal investigator for New Horizons. Here's the IAU definiton:

IAU said:
The IAU...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".

Footnotes:

[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.

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.
Click to expand...

The part called silly is part c of section 2. They must've meant clearing away similarly sized objects and dominating smaller objects in similar orbits, but didn't specifiy it in that way. So that means if Earth haven't cleared away the Near Earth Object asteroids, it's isn't a planet. There are a few known asteroids in the Trojan regions of Mars and Neptune orbits and Neptune haven't cleared away Pluto and a lot of other objects, so they are not planets. Jupiter haven't cleared out its 100,000 Trojan asteroids, so it's not a planet. They should have worded it more carefully and said cleared out similarly sized bodies and dominating smaller ones like Trojan objects instead of being too general.

Another silly thing is the replacement of the term minor planet with small solar system object. What about those not in our solar system? A not yet confirmed small object is thought to be orbiting pulsar PSR B1257+12 along with three confirmed planets detected by their periodic gravitational influence on the pulsar's signal. The small object can only be up to 0.2 Pluto or 0.0004 Earth mass. So it could be an extrasolar asteroid or comet. It would make sense to call it an extrasolar minor planet, but not an extrasolar small solar system object. So maybe the term is only meant for our solar system.

And another silly thing is that they're talking about Pluto as not being a planet, but calling it a dwarf planet. Isn't the word dwarf an adjective of the noun planet? It looks like a subset of planets, so they shouldn't call Pluto a nonplanet. It's like calling a sports car a noncar, a tabby cat a noncat for silly reasons like particular motor specifications or coat pattern that aren't core features of the basic type. Maybe the people who wrote this need an English class. :crazy: They should call the eight large planets major or large planets because that's the opposite of dwarf. Then we would really have at least 12 planets, with some being major and others being dwarf ones.

I read that only 400 something astronomers out of about 10,000 professional astronomers were allowed to vote. So it could've been done better. They call the defination 'final' and expect it to be official but they shouldn't be suprised that not everybody likes it like this::bowdown: It's just a defination and they can't enforce it. I came up with a different system that is just as valid and usable. They didn't send an army to the American Museum of Natural History when Pluto was removed from the Solar System exhibit there.

Splitting hairs by trying to do this with a wide range of different kinds of objects isn't that useful to science. They're still interesting objects and New Horizons will be the first one to see the type of object Pluto is up close and find things nobody knew before.
 
Well there are alot more planets out there than just 9 of them...over the years, the scienists found about 7 more or so planets out there and they are WWWWAAAAAAAYYYYYYYYY far out of our sight.

I'm not surprised that some ppl would think that pluto isnt a planet since it's a huge ball of ice anyway...and is WAY colder than Earth's north pole indeed. It would be hard to decided if its either a planet or not. of course, we all know the sun is not a "planet" but rather a huge ball of fire and is obviously the giant star we ever seen. So maybe pluto isn't really a planet but have the reason to be THAT far and maybe spread the cold around since its very far away from the sun...thats just my opinon.

science always change.
 
Will Pluto Ever Hit Neptune?
Monday August 28, 2006

Jason asks: "Since Pluto's orbit intersects Neptune's orbit, will Pluto ever crash into Neptune or become one of Neptune's moons?"

Answer: No. From 1979 to 1999, Pluto was the eighth planet from the sun. In 1999, it slipped beyond Neptune to become the ninth. But Pluto's 248-year orbit around the sun takes it 17 degrees above and below the plane in which Neptune and the other planets travel. So their paths don't actually cross as they swap positions. Imagine you are the sun in the middle of your back yard. The fence is Neptune's orbit. You toss a boomerang way out over the neighbor's houses and it comes back, being on both sides of your fence during its travels without hitting the fence. Of course, activity like that can be frowned upon, and in Pluto's case helped lead to its demotion.

LiveScience.com: Life's Little Mysteries - Will Pluto Ever Hit Neptune?
 
since they mentioned that pluto is not a planet and do travel outside the orbit. maybe it is just asteriod or a small giant ball of ice which will be evolved into a comet? i wonder? hmm..

yes sun is a BIG star.. not a planet definitely not.. amazing phenomena ..
 
Let imagine that you were a kid in a class to learn about the planets, and you did not write down the last planet - Pluto so you could get "F" grade on a report card. Now as present, a kid might also get "F" if he/she writes the Pluto. Kinda of interesting? :ty:
 
Here's a new way to remember the planets:

("Is Pluto a planet?")

Many Very Eager Minds Just Said Undoubtedly No.
 
Pluto: Down But Maybe Not Out
By Robert Roy Britt
LiveScience Managing Editor
posted: 31 August 2006
02:38 pm ET

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.

Lukewarm support

The definition basically states that the eight worlds from Mercury to Neptune are planets, and that Pluto and other small round objects in the outer solar system are not planets but will be referred to as dwarf planets.

The wording has been heavily criticized as being vague and arbitrary and failing to include planets around other stars. One highly controversial aspect is the idea that a planet must control a zone of space by clearing it of other objects. In fact, Earth and some of the giant planets have not cleared their paths—asteroids cross the planetary orbits frequently and in some cases orbit in lockstep with the planets.

Nonetheless, the Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) "recognizes the authority of the IAU to render a decision," today's statement reads. "All definitions have a degree of fuzziness that requires intelligent application: what does 'round' really mean? What does it mean to 'control a zone'?"

The statement suggests there are at least three years of wrangling ahead:

"These are technical issues to be addressed by Division III of the IAU, currently chaired by Ted Bowell, a fellow DPS member. There is still work to be done, too, in constructing a definition that is generally applicable to extra-solar planetary systems. These and other changes, radical or moderate, presumably will be addressed at the next IAU General Assembly in Rio de Janeiro in 2009, and the DPS community will continue to be involved in all stages of this process.

Lack of authority?

Other astronomers have said or indicated that the IAU decision might not carry much weight.

David Morrison, an astronomer at NASA's Ames Research Center, was in Prague for the debates and the vote. He called the resulting definition "reasonable" but termed the IAU process "highly convoluted."

"The definition of a planet is not primarily a science issue. Scientists can (and often do) use all sorts of jargon," Morrison told SPACE.com. "This issue is of interest because non-scientists, including writers of science textbooks, want a definition. Now they have one. But it is not obvious to me that planetary scientists will adjust their terminology because of the IAU votes."

The IAU's final proposal was lambasted by many astronomers for having been slapped together at the last minute and for not adhering to recommendations from two separate committees. Morrison was on an IAU committee of astronomers that debated for months on a definition proposal. The one they adopted, Morrison said, was approved by the committee in a vote of 11-8. But it never saw the light of day. Ultimately, another committee of seven, including historians, was formed by the IAU, and the second committee's proposed definition was scrapped too, in the last moments in Prague.

"Is Pluto, then, still a planet? Yes and no," Morrison said. "The answer is semantic, based on whether dwarf planets are planets, just as dwarf pines are pines. I would say that Pluto is a planet, but it is a dwarf planet, and the first example of the class of trans-Neptunian dwarf planets."

Lack of science

The whole debate, many astronomers say, has little if anything to do with science.

Geoff Marcy, a researcher at the University of California, Berkeley, has led the discovery of dozens of planets outside our solar system. "The astrophysics of planetary bodies is so rich and complex that defining 'planet' has never been an issue under discussion among professionals," Marcy said in an email interview earlier this week.

Pressed on whether the definition made any sense, Marcy said: "It makes no scientific sense to have a definition that pertains only to our solar system and not to other planetary systems."

The DPS represents 1,300 astronomers, about a third of them from outside the United States. Today's statement included a phrase that hints at the discontent felt among many members and the likelihood that all is not said and done:

"Ultimately, the definition of a planet will come through common usage and scientific utility. There is no need to throw away current school texts; Pluto has not gone away."

Full Coverage: The Debate and the IAU Vote
 
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