# Did there used to be twelve planets? **URL:** \ **Category:** Factual Questions\ **Created:** [August 24, 2006, 8:27pm UTC](https://boards.straightdope.com/t/did-there-used-to-be-twelve-planets/370087 "2006-08-24T20:27:14Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [August 24, 2006, 8:27pm UTC](https://boards.straightdope.com/t/did-there-used-to-be-twelve-planets/370087/1 "2006-08-24T20:27:14Z")
In the current news about Pluto’s demotion, I read a passing reference that when Ceres, Vesta, Pallas and Hygiea were first discovered they were classified as planets for several decades before being reclassified as asteroids. First I heard of this. Is it true that if you had asked somebody back around 1825 how many planets there were, he’d have told you twelve? ---
**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\ **Post date:** [August 24, 2006, 8:43pm UTC](https://boards.straightdope.com/t/did-there-used-to-be-twelve-planets/370087/2 "2006-08-24T20:43:12Z")
[QUOTE=Little Nemo] In the current news about Pluto’s demotion, I read a passing reference that when Ceres, Vesta, Pallas and Hygiea were first discovered they were classified as planets for several decades before being reclassified as asteroids. First I heard of this. Is it true that if you had asked somebody back around 1825 how many planets there were, he’d have told you twelve? [/QUOTE] In 1825 it would have been 11, and they would not have included Neptune (which was discovered in 1846). Four asteroids were discovered in 1800 to 1807, then Astraea in 1845 (making 12 planets), then Neptune would have been the 13th planet. But then in the next decade (1847-1856) another 36 asteroids were discovered, and in 1857-1866 a further 49 (making 91 up to the end of 1866). Some time during these discoveries astronomers would have decided that they couldn’t all be planets, and demoted the lot of them to take it back to 8. > **[List of minor planets: 1–1000](https://en.wikipedia.org/wiki/List_of_asteroids_%281-1000%29)** > > The following is a partial list of minor planets, running from minor-planet number 1 through 1000, inclusive. The primary data for this and other partial lists is based on JPL's "Small-Body Orbital Elements" and data available from the Minor Planet Center. Critical list information is also provided by the MPC, unless otherwise specified from Lowell Observatory. A detailed description of the table's columns and additional sources are given on the main page including a complete l Also see the summ... ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [August 24, 2006, 9:12pm UTC](https://boards.straightdope.com/t/did-there-used-to-be-twelve-planets/370087/3 "2006-08-24T21:12:57Z")
[QUOTE=Little Nemo] In the current news about Pluto’s demotion, I read a passing reference that when Ceres, Vesta, Pallas and Hygiea were first discovered they were classified as planets for several decades before being reclassified as asteroids. First I heard of this. Is it true that if you had asked somebody back around 1825 how many planets there were, he’d have told you twelve? [/QUOTE] Check out: [\*\* Bad Astronomy \*\*](http://www.badastronomy.com/)