# Pluto to be a planet again? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [October 3, 2014, 12:32am UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224 "2014-10-03T00:32:54Z")\ **Posts on this page:** 9\ **Page:** 3
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [October 3, 2014, 8:17pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/41 "2014-10-03T20:17:04Z")
I say this is all an astro-turf campaign quietly funded by Disney. I orbit the sun, and I’m pretty big, though I’m no Pluto. Still, I think I should be culturally defined as a planet. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [October 3, 2014, 9:02pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/42 "2014-10-03T21:02:42Z")
**Chronos** > [@](#): > > Certainly, the IAU’s current definition is absurd, since if applied consistently, it would rule out Earth. We share our orbit with another body large enough to be a planet-- In what sense have we “cleared our orbit”? Exactly. That classification is rather vague. Jupiter has [Trojan asteroids](http://en.wikipedia.org/wiki/Jupiter_Trojan) that orbit 60° ahead and 60° behind Jupiter. According to Wikipedia, there are 5,947 of these. That sounds as if Jupiter has done a rather lousy job in clearing its orbit. Will Jupiter suffer a planetary demotion because of this? ---
**Author:** ![Bozuit](https://avatars.discourse-cdn.com/v4/letter/b/edb3f5/32.png) [@Bozuit](https://boards.straightdope.com/u/Bozuit)\ **Post date:** [October 3, 2014, 9:42pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/43 "2014-10-03T21:42:48Z")
> [@Chronos](#): > > Certainly, the IAU’s current definition is absurd, since if applied consistently, it would rule out Earth. We share our orbit with another body large enough to be a planet-- In what sense have we “cleared our orbit”? > [@wolf\_meister](#): > > Exactly. That classification is rather vague. > > Jupiter has [Trojan asteroids](http://en.wikipedia.org/wiki/Jupiter_Trojan) that orbit 60° ahead and 60° behind Jupiter. According to Wikipedia, there are 5,947 of these. That sounds as if Jupiter has done a rather lousy job in clearing its orbit. > Will Jupiter suffer a planetary demotion because of this? Not “exactly”. Not even close. Earth’s orbit is the _most_ “clear”, relative to its mass, of all the planets in the Solar System. “Clearing the orbit” or “clearing the neighbourhood” means that other objects within the orbit of the body in question are under the influence of that body’s gravity. This means satellites and trojans have no bearing on whether or not a body is classified as a planet. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [October 3, 2014, 10:01pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/44 "2014-10-03T22:01:09Z")
I gave up on Pluto once I found and looked into the term quasi-satellite and how there are many such objects that are in a 3:2 resonance orbit with Neptune. It seems like Pluto has many quasi-satellites which would seem to help it’s planetary status but looking into it that is only because Neptune’s orbit is the reason they are all there, including Pluto. In other words the quasi-satellites are not Pluto’s but Pluto and the other quasi-satellites are in such a orbit because of Neptune. ---
**Author:** ![Dendarii\_Dame](https://avatars.discourse-cdn.com/v4/letter/d/bbce88/32.png) [@Dendarii\_Dame](https://boards.straightdope.com/u/Dendarii_Dame)\ **Post date:** [October 5, 2014, 8:11pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/45 "2014-10-05T20:11:10Z")
Personally, I’d go with whatever Interplanet Janet suggested. “There’s never been a planet Janet hasn’t seen.” And she saw Pluto. (Yes, she’s also been to the Sun, but I think we can agree that’s an exception. She said, “It’s a star!” and got its autograph.) 🙂 ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 5, 2014, 8:44pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/46 "2014-10-05T20:44:56Z")
[Wikipedia:](http://en.wikipedia.org/wiki/Planet#20th_century) > [@](#): > > In the absence of any formal definition, a “planet” came to be understood as any “large” body that orbited the Sun. Because there was a dramatic size gap between the asteroids and the planets, and the spate of new discoveries seemed to have ended after the discovery of Neptune in 1846, there was no apparent need to have a formal definition. > [@](#): > > However, in the 20th century, Pluto was discovered. After initial observations led to the belief it was larger than Earth, the object was immediately accepted as the ninth planet. Further monitoring found the body was actually much smaller: in 1936, Raymond Lyttleton suggested that Pluto may be an escaped satellite of Neptune, and Fred Whipple suggested in 1964 that Pluto may be a comet. However, as it was still larger than all known asteroids and seemingly did not exist within a larger population, it kept its status until 2006. Pluto has been a planet since it was discovered. In 2006 the IAU decided to create their own definition of planet that excluded Pluto. The concept of a planet that included Pluto had been recently formed when the planet was discovered. Prior to that the concept included at various times 3 large asteroids and the sun and the moon. So Pluto may not be an IAU defined planet currently, but using the commonly accepted concept of a planet it has been a planet since it was discovered and remains so. The IAU made a mistake by redefining a commonly understood term on an arbitrary basis. Scientific terminology should be selected based on clarity. They could have easily used different or qualified terms to distinquish orbiting bodies in our solar system. Pluto is now designated a Dwarf Planet while eight other bodies retain their designation as a Planet. They could easily have divided into Major and Minor planets or even more sensible categories that would not include both Mercury and Jupiter in a single definition. Kudos to Dr. Gingerich for being a champion of common sense. ---
**Author:** ![Wallaby](https://avatars.discourse-cdn.com/v4/letter/w/dc4da7/32.png) [@Wallaby](https://boards.straightdope.com/u/Wallaby)\ **Post date:** [October 5, 2014, 9:34pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/47 "2014-10-05T21:34:55Z")
> [@ElvisL1ves](#): > > Gotta read Mike Brown’s _How I Killed Pluto and Why It Had It Coming_, people. He’s not only a brilliant astronomer, responsible for finding enough Kuiper Belt Objects to establish that Pluto is one of them, he’s a marvelously entertaining writer too. This. Excellent book. I like his description of how an alien approaching the Solar System would describe what he sees. (Pause for ‘oogly oogly’ jokes. Thank you). First there would be a massive cloud of small icy bodies. Then a massive group of small, rocky bodies. Then, when the rocky bodies thin out significantly, there would be 4 large gas planets. Then another ring of small rocky bodies. Then a group of 4 reasonably large rocky planets. Then the sun. It makes far more sense to look at the Solar System as an entire structure (based on the sun’s gravitational effects), rather than just the Sun and whichever objects we arbitrarily choose to call the planets, while ignoring the rest. ---
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [October 5, 2014, 10:04pm UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/48 "2014-10-05T22:04:54Z")
I certainly hope it is deemed a planet again. If not, my Intergalactic passport may not be valid for travel to Pluto. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [October 6, 2014, 11:11am UTC](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224/49 "2014-10-06T11:11:01Z")
I hope it remains _not_ a planet. The word should not be “culturally defined” in a scientific context that doesn’t reference date of discovery or any such post-hoc attempt to include Pluto but exclude all the other KBOs…Either Pluto _is_ a planet and all the other large KBOs are , or Pluto is not and neither are the other KBOs. Preferably the latter. [Previous page](https://boards.straightdope.com/t/pluto-to-be-a-planet-again/700224.md?page=2)