Pluto no longer a planet!! Down to 8.

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Tachyon
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Post by Tachyon »

Science is constantly evolving, and new information is always being added. What is true today may not be tomorrow. However, I believe mistakes of the past should remain unless it is a fundamental misconception or hinders progress for the future. If Pluto was misidentified as a planet in the past, so be it! Will it cause the science of astronomy to be advanced backwards significantly if it is still called a planet? We could always set a rule that henceforth all objects to qualify for a planet should have the new criteria, but we do well to leave non-significant past mistakes alone.

To me, there are still 9 planets in our solar system, whatever the books may say...
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gwenyi
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Post by gwenyi »

it's always difficult to accept a change after you are so used to the system for such a long time.

something like u wake up every morning to run and suddenly u stop running for a day. u'll that feel something is amiss.

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jennifer1611991
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Post by jennifer1611991 »

I AM VERY UNHAPPY ABOUT THIS! I mean, i was going to buy an astronomy book and now, they're gone! YOU SEE WHAT HAPPENS WHEN YOU CHANGE THINGS! you know what, i can't wait till that space satelite thing reaches pluto. If it finds something that proves Pluto's a planet, well...=)... I'll be celebrating..

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philip
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Post by philip »

:( I too feel sad that Pluto was demoted, But on bright side the Universe will suprise us more :P much more. I have to let go of Pluto now and move on to the invisible Darkmatter as the next thing. Remember during Galileo time, he put in new ideas and model of OUR SOLAR system. He was jailed for that. I know we are passionate but must contain ourselves. Classify our solar system now then later. Children born after 2006 will benefit from this :D My 2 cents BTW, When Metric system was inroduced in Singapore back at 70, USA still uses imperial Inches and Feet now!. got the picture?my 1 cents
starry night, sunny day, nice day

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ALPiNe
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Post by ALPiNe »

Awwww.. Oh come on… Quit whining guys… No one has said anything about voting Pluto out in the first place. IAU merely agreed on consensus the definition of a ‘planet’ which unfortunately, Pluto didn’t make the grade. What’s the big deal really if only 400+ voted for the definition that would exclude Pluto? There’s no mentioning of the other ~2299 members voting against the decision during the IAU General Assembly? Where were these professionals and what were they doing? Eating popcorns? :roll: The decision has already been made, and now they are crying over spilled milk? It just goes to show one thing: that these professionals are indecisive or just sitting on the fence. No? Then these are probably some of the reasons why:

1) They didn’t know what a ‘planet’ is to begin with.
2) They didn’t know how to define a ‘planet’.
3) They intend to spend another 76 years to define what a ‘planet’ is.
4) They have better things to do then to define what a small icy ball of rock is.
5) “Heck, Pluto will be a planet because it IS a planet.”

Yes, it is a great embarrassment for the IAU to have such chaotic outcomes. But so what? Science is blind to the wimps of professionals and non-professionals alike. The Solar System isn’t going to change how it functions just because we think it should behave in a certain way, nor is it going to thank Earth for leaving Pluto alone and giving it 9 planets altogether.

If we have to come to a compromise on this whole issue, a sound and logical approach would be to focus not on Pluto, but strictly on defining what sets apart planets from the non-planets. Just putting 100% focus only on Pluto isn’t going to help much, which is too myopic. Step out, look at the bigger picture and you might see things differently.

Anyway, it’s nice knowing that Pluto has so many fans. If you love Pluto, then get out there and take a look at him. A 12-inch scope will show him up nicely.


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- ALPiNe
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ALPiNe
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Post by ALPiNe »

For those who really love Pluto, you might want to check out these links and do your part:

http://www.petitiononline.com/PP896/petition.html

http://www.cafepress.com/JusticeForPluto

http://www.spreadshirt.net/shop.php?sid=168240


Cheers,
- ALPiNe
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Last edited by ALPiNe on Mon Aug 28, 2006 6:08 pm, edited 1 time in total.
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ALPiNe
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Post by ALPiNe »

chrisyeo wrote:"Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's. " Seems that pluto was disqualified because it had not "cleared the neighborhood around its orbit".

However, that seems to disqualify Neptune as well as it had not cleared its orbit of Pluto ! Hmm..
"Although Pluto's orbit does in fact cross that of Neptune, it would be misleading to say that Neptune has failed to dominate its orbital zone. Pluto is just the largest (apparently) of a broad class of objects that are each in a 3:2 resonance with Neptune. That is to say, they complete two orbits for every three of Neptune's. These objects are called plutinos. They constitute the inner edge of the Kuiper Belt.

There are also objects called twotinos, which as you might expect, are in a 2:1 resonance with Neptune. They complete one orbit for every two of Neptune's. They *seem* to represent the outer edge of the Kuiper Belt, although it may be possible that there is merely a small gap, and there are more distant objects beyond that gap. However, that is not expected to be the case.

In part because of these resonances, none of these bodies approaches closer to Neptune than about 15 AU, and I don't think their orbits get any closer than about 5 AU.

Let's face it, the definition, as stated in the news release, is not designed to be precise. It is supposed to state the intent of the classification; it remains to the rivet artists to make the definition more precise, I suppose."

*Credits to Brian Tung <brian@praesepe.isi.edu>.


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ALPiNe
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Post by ALPiNe »

weedee wrote:Maybe the term "planets" was wrong from the start. The Greek astronomers called them "wanderers" because they see the planets move across the night sky.. Pluto's motion is hardly observable at all even with amateur telescopes.
Or maybe you just need to get yourself a more competent telescope. Even at 19.2 AU, Uranus’ motion is not easily detectable with small telescopes, not to mention Pluto’s.

weedee wrote:I guess the term "planet" should just be scrapped and we should all stick with "satelites of a star"
‘Planet’ is just a word, so there’s nothing wrong with it. But I have to agree that perhaps, the meaning or concept to which we attach to the word ‘planet’ has to be scrapped in order for us to classify the celestial objects in a more systematic order. To put it in perspective, we can throw in the term ‘Cabody’ to define what those planets are. But again, are ‘Cabodies’ planets? Moons? Or does ‘Cabody’ mean something else?


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ALPiNe
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Post by ALPiNe »

weedee wrote:hmm what does the part on "clearing its neighbourhood around the orbit" means?

there was a claim that due to trojan asteroids sharing Jupiter's orbit, Jupiter wont qualify for it..

and does it mean that it has a roche limit wide enough to significantly crumble a good area around its path?
If you have heard of the Trojan asteroids, then most likely you would have heard about the Lagrange points too, so I’m surprised why Roche limit was even mentioned in the first place. The Trojan asteroids are actually caught in a stable orbit near the L4 and L5 points ahead of Jupiter by about 60 degrees and following Jupiter by 60 degrees to balance the gravitational pull of the Sun and Jupiter. To visualize this, follow this link.

Unlike the Trojan asteroids, Jupiter’s gravity is able to ‘sweep away’ most debris that do not fall within the L1 and L2 points, thus keeping Jupiter isolated from other celestial objects. For those objects that do however, fall within the L1 and L2 points, they become Jupiter’s moons. In fact, the L1 and L2 points are what constitute the radius of the Hill Sphere, which is a gravitational sphere of influence of one astronomical body (Jupiter) on a third body (Moon). The Hill Sphere is not to be confused with Roche limit as the latter takes into account the tidal forces that would break up an object.

chrisyeo wrote:From Wikipedia: "clearing the neighbourhood"
Clearing the neighbourhood" is an informal description of part of the process of planet formation.

The phrase refers to an orbiting body "sweeping out" its orbital region over time, by gravitationally interacting with smaller bodies nearby. Over many orbital cycles, a large body will tend to cause small bodies either to accrete with it, or to be disturbed to another orbit. As a consequence it does not then share its orbital region with other bodies of significant size, except for its own satellites, or those collected later under its gravitational influence (such as Trojan asteroids).

[...]

The concept has been used by the IAU in its August 2006 redefinition of the term "planet" as one of the criteria differentiating a planet from a dwarf planet; a planet is a body with sufficient mass to largely clear its orbit of other objects. The IAU determined that Pluto will now be considered a dwarf planet because it has not cleared the neighborhood of its orbit (vis-à-vis Neptune and Kuiper Belt Objects such as the Plutinos).
If I am interpreting the IAU’s third criteria correctly, then the main concept behind the criteria used to define planets is also derived from Lagrange points. If an object is massive enough, it will be able to keep out most asteroids at the L4 and L5 points in order to balance its orbit around the sun, while retaining only a small number at its unstable L1 and L2 points. This criteria used could also have been due to IAU’s consideration of having a planet that is sufficiently massive enough to support its own orbit around the sun. To verify this though, maybe an expert in Astrophysics can feedback on this.


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weixing
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Post by weixing »

Hi,
Or maybe you just need to get yourself a more competent telescope. Even at 19.2 AU, Uranus’ motion is not easily detectable with small telescopes, not to mention Pluto’s.
Just wonder which telescope is competent enough to be able to observe Pluto?? Hubble Space Telescope?? Hee hee :P :P
Anyway, it’s nice knowing that Pluto has so many fans. If you love Pluto, then get out there and take a look at him. A 12-inch scope will show him up nicely.
Hmm... yes... show him nicely as a... dot (so which dot is Pluto???)... hee hee :P :P

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Yang Weixing
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