# Was Pluto the 8th planet from 1969 to 2009 and Neptune the 9th? **URL:** \ **Category:** Factual Questions\ **Created:** [May 2, 2011, 10:10am UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463 "2011-05-02T10:10:39Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [May 2, 2011, 9:28pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/21 "2011-05-02T21:28:18Z")
> [@The\_Man\_In\_Black](#): > > Sure it is. A bunch of geeks got together and voted that it isn’t a planet. We can get another group of geeks together and vote that it is a planet. Except that isn’t the case at all. The definition of planet has changed much over the centuries; at first it simply meant “point of light in the night sky with a noticeable movement against the background of the seemingly fixed stars.” When that definition was current there were only 5: Mercury, Venus, Mars, Jupiter, & Saturn. (Earth was not considered a planet.) As our knowledge expanded we discovered about the nature of the solar system, including the fact that those bodies were all much nearer to Earth than the fixed stars, and qualitatively different from them, and that the first three bodies were more like one another (and Earth) than any of them were like the latter two. So the definition was changed to make the word _planet_ something not quite so arbitrary. As we’ve learned more, the word as used by scientists has been adjusted. Does it bother you that atoms aren’t indivisible? ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [May 2, 2011, 9:29pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/22 "2011-05-02T21:29:29Z")
> [@Elendil\_s\_Heir](#): > > Well… I wouldn’t put up too much of a fuss if you wanted to name it after me. > > :: blushes :: So we can call them _isildurs_? ---
**Author:** ![Mr.Excellent](https://avatars.discourse-cdn.com/v4/letter/m/f19dbf/32.png) [@Mr.Excellent](https://boards.straightdope.com/u/Mr.Excellent)\ **Post date:** [May 2, 2011, 9:33pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/23 "2011-05-02T21:33:07Z")
> [@Lemur866](#): > > Pluto is a tiny ball of ice, and there are lots of larger balls of ice out there in the Kuiper Belt. You really want to call every little iceball we find out there a planet? Sure, if it maintains a spheroid shape due to gravitational attraction, has cleared its orbital neighborhood, and does not orbit another body (besides the Sun, of course). Why not? 😉 ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 2, 2011, 9:44pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/24 "2011-05-02T21:44:51Z")
> [@Skald\_the\_Rhymer](#): > > So we can call them _isildurs_? That’s not very damned funny. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [May 2, 2011, 9:52pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/25 "2011-05-02T21:52:33Z")
> [@Elendil\_s\_Heir](#): > > That’s not very damned funny. Next time I will point out that Venus is actually a guy in a flying sailboat with a magic sapphire on his forehead. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [May 2, 2011, 10:29pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/26 "2011-05-02T22:29:36Z")
The term 9th planet means 9th planet from the sun. If you were given interstellar directions and was told to go to the 9th planet from the sun during that time period that would mean Neptune. ---
**Author:** ![Biffy\_the\_Elephant\_Shrew](https://avatars.discourse-cdn.com/v4/letter/b/e47c2d/32.png) [@Biffy\_the\_Elephant\_Shrew](https://boards.straightdope.com/u/Biffy_the_Elephant_Shrew)\ **Post date:** [May 2, 2011, 10:35pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/27 "2011-05-02T22:35:40Z")
> [@Chronos](#): > > Mercury, Venus, Earth, Luna, Mars, and Ceres are rockballs, Jupiter, Saturn, Uranus, and Neptune are gasballs, and Pluto, Eris, Quauar, Sedna, and a bunch of other objects are iceballs. So the generic term for all three would be _spaceballs_? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 2, 2011, 10:36pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/28 "2011-05-02T22:36:31Z")
> [@](#): > > You forgot to use Latin terms for your categories. OK, “rockballus”, “gasballus”, and “iceballus”. Happy now? 😉 And a nitpick to **Skald** , in classical times there were seven planets, not five. The Sun and Moon were also included in that category. And it’s a flying _aluminum_ sailboat with a magic sapphire. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 2, 2011, 10:40pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/29 "2011-05-02T22:40:01Z")
Quoth **Biffy** : > [@](#): > > So the generic term for all three would be spaceballs? No, by analogy a “spaceball” would be a spherical object composed primarily of space, which would presumably refer to a black hole. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [May 2, 2011, 10:52pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/30 "2011-05-02T22:52:55Z")
> [@Chronos](#): > > OK, “rockballus”, “gasballus”, and “iceballus”. Happy now? 😉 > > And a nitpick to **Skald** , in classical times there were seven planets, not five. The Sun and Moon were also included in that category. > > And it’s a flying _aluminum_ sailboat with a magic sapphire. There’s no proof it was a sapphire. You should have nitpicked THAT. You’re right about the sun and moon being considered planets by the Greeks & Romans. And someone who isn’t me could make a good argument that Luna should still be considered a planet; I’ve emailed her with a request to join us. Count me in the group that thinks they were right to declassify Pluto as a planet; I thought so as long as sophomore year astronomy. (By which I mean Brother What’s-his-name convinced me so.) But I also have a problem with calling the terrestrial planets the same sort of body as the gas giants. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [May 2, 2011, 11:18pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/31 "2011-05-02T23:18:32Z")
> [@Chronos](#): > > And it’s a flying _aluminum_ sailboat with a magic sapphire. Hey! ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [May 2, 2011, 11:25pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/32 "2011-05-02T23:25:41Z")
> [@Skald\_the\_Rhymer](#): > > The definition of planet has changed much over the centuries; at first it simply meant “point of light in the night sky with a noticeable movement against the background of the seemingly fixed stars.” When that definition was current there were only 5: Mercury, Venus, Mars, Jupiter, & Saturn. (Earth was not considered a planet.) Depending on how strictly you want to hang on the the “point” bit, the moon and the sun could also be considered to be planets (the moon was considered a planet in some Greek astronomical systems, AFAIK, though the sun might not have been). ETA: beaten by a mile by Chronos. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [May 2, 2011, 11:37pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/33 "2011-05-02T23:37:50Z")
> [@Superfluous\_Parentheses](#): > > Depending on how strictly you want to hang on the the “point” bit, the moon and the sun could also be considered to be planets (the moon was considered a planet in some Greek astronomical systems, AFAIK, though the sun might not have been). **Chronos** beat you to it. Hang your head in shame, as you also repeated my erroneous use of the word _point_ in the definition. In the future we will expect better of you. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 2, 2011, 11:47pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/34 "2011-05-02T23:47:54Z")
> [@](#): > > And someone who isn’t me could make a good argument that Luna should still be considered a planet; I’ve emailed her with a request to join us. I’m one such person: You’ll note that I included Luna on my list of rockballs. It meets the criteria: It feels a stronger gravitational force from the Sun than from the Earth, it orbits (more or less) in the plane of the ecliptic (certainly closer to the ecliptic than to the Earth’s orbital plane), it’s big enough to maintain a spherical shape from gravity, it’s got a planet-like composition. It hasn’t cleared its orbit, but that’s a silly criterion anyway, since neither has Earth. And good point about the sapphire. Some of the Elven-gems are explicitly said to have been made from mithril, but the Silmarils weren’t specified. ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [May 2, 2011, 11:49pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/35 "2011-05-02T23:49:25Z")
> [@Skald\_the\_Rhymer](#): > > **Chronos** beat you to it. Hang your head in shame, as you also repeated my erroneous use of the word _point_ in the definition. In the future we will expect better of you. Well blast your eyes. 😃 [Here’s a video of Sagan to make up for things.](http://www.youtube.com/watch?v=p9TIeuBF9Ss) ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [May 2, 2011, 11:53pm UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/36 "2011-05-02T23:53:00Z")
> [@Chronos](#): > > I’m one such person: You’ll note that I included Luna on my list of rockballs. It meets the criteria: It feels a stronger gravitational force from the Sun than from the Earth, it orbits (more or less) in the plane of the ecliptic (certainly closer to the ecliptic than to the Earth’s orbital plane), it’s big enough to maintain a spherical shape from gravity, it’s got a planet-like composition. It hasn’t cleared its orbit, but that’s a silly criterion anyway, since neither has Earth. So are you in the _Terra & Luna are a double-planet system crowd_ too? ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [May 3, 2011, 12:09am UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/37 "2011-05-03T00:09:27Z")
> [@Superfluous\_Parentheses](#): > > [Here’s a video of Sagan to make up for things.](http://www.youtube.com/watch?v=p9TIeuBF9Ss) That was _fantastic_. What a spectacular idea, to take that photograph, and what a speech to go with it! ---
**Author:** ![cochrane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cochrane/32/10441_2.png) [@cochrane](https://boards.straightdope.com/u/cochrane)\ **Post date:** [May 3, 2011, 12:31am UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/38 "2011-05-03T00:31:27Z")
> [@Bytegeist](#): > > So if you’re going to insist Pluto’s a planet despite them, I think you should come up with a new name for it too. I vote we name it Goofy. Who’s with me? ---
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [May 3, 2011, 1:06am UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/39 "2011-05-03T01:06:03Z")
> [@Hari\_Seldon](#): > > Although I was perfectly aware that Pluto was inside Neptune’s orbit, it would never have occurred to call it anything but the ninth planet. Yeah, I thought everyone knew about it. It’s what I was taught in elementary growing up. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [May 3, 2011, 3:52am UTC](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463/40 "2011-05-03T03:52:45Z")
> [@Mahaloth](#): > > Yeah, I thought everyone knew about it. It’s what I was taught in elementary growing up. It’s not like the teachers ever taught something wrong by over simplifying it is it. This is why I asked the question. I thought there might be people, besides the author that considered Pluto would be the 8th planet during the stated period. I was interested in what was the point of view when the book was published. [Previous page](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463.md?page=1) [Next page](https://boards.straightdope.com/t/was-pluto-the-8th-planet-from-1969-to-2009-and-neptune-the-9th/580463.md?page=3)