is pluto a planet??

Question

my friend told me that pluto has been takin out of the listings as a planet.... is this true she said it was on the news??

Answer 1

DEFINITIONS

The International Astronomical Union held a meeting in Prague on 24th August at which it passed three new definitions, of a planet, a dwarf planet and a Small Solar System Body. The IAU definitions are:

PLANET: a celestial body having all the following attributes as a "planet". It:

(1) is in orbit around a star or stellar remnants;
(2) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape;
(3) is above the minimum mass/size for a planet in our solar system*;
(4) if in our solar sytem it has cleared the neighbourhood around its orbit; and
(5) is below the limiting mass for thermonuclear fusion of deuterium.

(*What this mass/size is has not been specifically defined. However, it must be somewhere between the mass required in (2) above, and the mass of the planet Mercury.)

Our solar system is considered to have eight planets under this definition: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Three bodies in orbit around our Sun and which only fulfil conditions (1) and (2), but not (4), and are not natural satellites, are now classified as dwarf planets: Ceres, Pluto and Eris. To date, there have been more than two hundred planets discovered orbiting other stars.

The IAU further defines any celestial object having any of the following attributes as not being a planet:

(1) it is below the minimum mass/size for a planet in our solar system;
(2) it is above the limiting mass for thermonuclear fusion of deuterium; or
(3) it is a free-floating object in a young star cluster.

(MY INTERJECTION: the point about fusing deuterium is to distinguish planets from brown dwarf stars, which can be as small as about twelve Jupiter masses.)

DWARF PLANET: a dwarf planet as an object 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
c) Has not "cleared the neighbourhood" around its orbit
d) Is not a satellite of a planet, or other nonstellar body

SMALL SOLAR SYSTEM BODY: A small solar system body (SSSB) is a term defined in 2006 by the International Astronomical Union to describe solar system objects which are not planets or dwarf planets:

"All other objects orbiting the Sun shall be referred to collectively as "Small Solar System Bodies" ... These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies."

Therefore it refers to these objects that can be further classified based on their orbit or composition:

all known minor planets that are not dwarf planets, i.e.:
i) the classical asteroids (except the largest one, 1 Ceres);
ii) the Centaurs and Neptune Trojans;
iii) the smaller Trans-Neptunian Objects (except dwarf planets such as Pluto and Eris);
iv) all comets;

It is not yet clear whether there will be a lower bound on the group of small solar system bodies, or if it will encompass all material down to the level of meteoroids.

Some of the larger "small solar system bodies" may be reclassified in future as dwarf planets, pending further examination to determine whether or not they are in hydrostatic equilibrium.

MY COMMENT: All rather legalistically phrased and a little dry to read, but that is because these were formal motions put to a General Assembly for approval.

HISTORY

There have been as many as 27* solar system bodies that were greeted as planets on discovery (most recently first Sedna and then Eris were so hailed by newspapers when they were discovered) but were later removed from that status, so Pluto is merely the latest in a long line to have been reclassified, The number of planets has gone up and down like a yo-yo as a result.

First to get the chop, in the 16th Century, were the Sun and the Moon, regarded as planets from antiquity.

Then in the 17th Century, the 4 Galilean moons of Jupiter and Titan, Iapeter and Rhea, the first 3 moons of Saturn to be discovered. were defined by their discoverers as planets but came to generally be regarded as moons, as that new concept became accepted.

Since the acceptance of the heliocentric model over the geocentric model, the solar system has been seen as having various numbers of accepted planets over the years:

1543 - six (Mercury, Venus, Earth, Mars, Jupiter and Saturn) (among those who accepted the new view)
1781 - seven (with Uranus)
1807 - eleven (with 1 Ceres, 2 Pallas, 3 Juno and 4 Vesta)
1845 - twelve (with 5 Astraea)
1846 - thirteen (with Neptune)
1851 - twenty-three (with 6 Hebe, 7 Iris, 8 Flora, 9 Metis, 10 Hygiea, 11 Parthenope, 12 Victoria, 13 Egeria, 14 Irene and 15 Eunomia)
1852 - eight (without Ceres and the asteroids)
1930 - nine (with Pluto)
2006 - eight (without Pluto)

When the objects 1 Ceres, 2 Pallas, 3 Juno and 4 Vesta were found orbiting between Mars and Jupiter in the early 1800s, they were declared and accepted as planets (though Herschel, who had discovered Uranus 20 years beforehand, felt they were disappointingly small and did not really rank alongside his discovery; he therefore coined the term "asteroid" for them),

They remained classed as planets for many years. However, as more and more objects began to be found in the same region of the solar system, they became classified as asteroids, along with their orbital kin. Just as well as we now know of over 340,000 asteroids. To have 340,0008 planets would be getting silly.

A similar scenario has occurred with Pluto. It was first discovered beyond Neptune in 1930 and was accepted by the IAU as a planet after it was initially believed to be larger than the Earth. However, after further observation it was found that Pluto was actually much smaller, being less massive than the Moon.

After more than 1,000 similar new bodies were found beyond Neptune during the 1990s and the early 2000s, the IAU decided to reclassify Pluto as a dwarf planet in 2006.

Answer 2

Pluto, the last planet to join the heavenly pantheon, became the first to leave it. The status of Pluto had been under discussion for some time, but with the discovery of 2003 UB313, nicknamed Xena, the question became acute, for it seemingly had as much right as Pluto to be called a planet.

On August 24, 2006, the International Astronomical Union surprised the world by voting in a new definition of planet, one that would exclude Pluto and bring the total number down to eight. (There had previously been been strong speculation that the redefinition would bring the total up to 12 instead of down.)

Pluto was instead classified as a dwarf planet, along with Ceres and the aforementioned Xena. The main difference between a dwarf planet and the real thing is that the dwarf variety has not cleared the area of its orbital path.

This redefinition met with a wave of protests from those who wanted to see the ninth planet grandfathered in, including but not limited to supporters of the late Clyde Tombaugh, who discovered Pluto in 1930. His widow, however, said he would have been accepting of the IAU's decision since "he was a scientist" and understood that astronomers had to take into account newly discovered objects in the Kuiper Belt (where Pluto is located).

But opponents of Pluto's demotion remain unconsoled and have generated a thriving industry in T-shirts, mugs and other memorabilia. Among the many slogans of this movement was one which played on the mnemonic for the names of the erstwhile nine:

Answer 3

A few hundred astronomers at an IAU voted to create a definition of "planet" and Pluto doesn't meet its definition. It's just a nomenclature thing. Nothing changed about Pluto. It's still a frozen ball orbiting the Sun. It doesn't care what we call it.

What they decided does make some sense: they're finding more objects like Pluto out there, some bigger. If Pluto's a planet then all those other ones ought to be (and we might have thousands of "planets" in the Solar System). Or if those other big ones out there aren't planets, then Pluto shouldn't be one.

But keep calling it a planet if you want. There aren't any astronomy police who'll come after you.

Answer 4

Sorry, Pluto's off the list.

Pluto Gets Downsized
[e-mail]

Prague - The international committee of astronomers decided this week to remove Pluto from the list of planets. A spokesman released this statement, "We're awfully sorry to have to let Pluto go, but this restructuring is necessary to move this solar system forward. We've got to tighten our asteroid belt and make difficult decisions. We've really enjoyed working with Pluto in the past and wish it no ill will. We look on this event as a great opportunity to revitalize our system."
Behind the scenes however, things were reportedly more heated. Rumors abound that Pluto orbited slower than other planets, often appearing sluggish and possibly intoxicated. Some have reportedly complained about off color jokes directed at Uranus. Lawsuits by several asteroids demanding inclusion in the solar system reportedly also motivated the committee to take a hard line on planet definition. An original plan to use the world "Pluton" was rejected by their lawyers as demeaning and discriminatory.

Others have defended Pluto, claiming the decision to downsize was based on unjust discrimination. One anonymous insider claimed, "It's a new solar system, and if you're not wearing rings, or you're too small, you're just not flashy enough for the kids today. Besides, the committee was always uncomfortable with the attraction between Pluto and its long-term partner, Charon. It's just prejudice I tell you."

Pluto's press agent released this statement, "While Pluto is saddened by this turn of events, it's not bitter, rather Pluto looks on this as an oportunity to explore new and exciting projects."

Answer 5

Pluto is not a planet as our earth is it is a dwarf planet , and it has been said by astronomres bcoz pluto is even smaller than the moon 10,000,000 plutos will fit in the sun and eris is even larger than pluto . pluto has lost it's 7 decade status and it is not the first time for a planet to be disapproved , ceres which is now discovered was a planet in the olden times for 5decades and then was disapproved because it was said to be an asteroid and not a planet and was considered as the largest of the asteroids I gined this knowledge from the net www.space.com a few years ago and if you have any doubts about this answer you may check it I just want everyone to gain knowledge and to know more on planets and disapproved planets and pictures of planets visit: www.hubblesite.org/gallery this is the best site .
(If you like this answer then please vote for it as the best answer)

Answer 6

Pluto has been demoted to what they are now referring to as a Pluton, the same as its moon Charon, the asteroid Ceres and the body that had been known as Xena.

BUT, what the astronomers haven't figured out, is that in truth, Pluto is an example of something that is so rare, its never been seen before, and when the satellite currently on its way to study Pluto proves it, Pluto will be promoted back to being a planet.

What Pluto actually is, is one part of a binary planet. The other part is Charon. Instead of being a planet and moon, the two bodies revolve around each other, as well as revolving around the sun. That is the cause in the wobble in its orbit, and why the astonomers falsely demoted it.

Eventually they will learn to look at things with an OPEN mind.

Answer 7

pluto is not a planet. pluto and charon are considered a binary system, but two small bodies orbit this system. they are called nix and hydra.

http://www.iau.org/fileadmin/content/pdfs/Resolution_GA26-5-6.pdf
http://en.wikipedia.org/wiki/Pluto

pluto orbits the sun, is round, does not have an isolated orbit (a bunch of other similar bodies have similar orbits.), and is not a satellite so it is a dwarf planet. this does not change anything about the solar system or pluto. it just corrects the mistake of classifying pluto as a planet initially.

this same thing has happened before. beginning in 1800, astronomers found a few bodies orbiting between the orbits of mars and jupiter, and they finally stopped calling them planets after the fourth discovery. astronomers then added numerals to the names, and pluto recently got its numeral. 150 years from now, no one will think of "134340 pluto" as a planet. very few will even know we classified it as a planet. "1 ceres" and "136199 eris" are other dwarf planets.

i have been waiting for this since i was about twelve. i feel somewhat satisfied. i knew that pluto didn't fit the pattern set by the major bodies in the solar system so it was an anomaly. it just felt illogical and "out of place". this was the right thing to do, believe me. i don't understand why so many are having such a problem with this.

i don't know how long this will drag on tho. many planetary scientists are not satisfied that the definition is rigorous enough.

Answer 8

No, it is not a planet, and never has been, according to recent IAU guidelines. This is because Pluto has not cleared its orbit of other bodies, as its orbit crosses Neptune's, and contains other Kuiper Belt objects.

There are many good reasons why Pluto is not a planet:

1. It is quite a bit smaller than our own Moon.
2. It has not cleared its orbit.
3. Eris is larger than Pluto.
4. Its orbit is inclined to the ecliptic by about 17 degrees.
5. It is a Kuiper Belt Object.

Answer 9

Pluto (officially designated 134340 Pluto) is the second-largest known dwarf planet in the solar system.

In August of 2006 the International Astronomical Union (IAU) redefined the term "planet", and classified Pluto, Ceres, and Eris as dwarf planets.Pluto is also classified as the prototype of a family of trans-Neptunian objects. After the reclassification, Pluto was added to the list of minor planets and given the number 134340.

Answer 10

Yes. The International Astronomical Union demoted it to the status of 'minor planet' after a majority voted to put a new few rules that define what a planet is. The rule that Pluto didn't meet was "A planet must also dominate it's surroundings and clear the neighbourhood around its orbit."

Answer 11

Yes Pluto is no longer a planet.