# planets **URL:** \ **Category:** Factual Questions\ **Created:** [January 27, 2010, 6:00am UTC](https://boards.straightdope.com/t/planets/526631 "2010-01-27T06:00:40Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![BigBertha](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@BigBertha](https://boards.straightdope.com/u/BigBertha)\ **Post date:** [January 27, 2010, 6:00am UTC](https://boards.straightdope.com/t/planets/526631/1 "2010-01-27T06:00:40Z")
Was there ever a planet between mars and jupiter? ---
**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:** [January 27, 2010, 6:21am UTC](https://boards.straightdope.com/t/planets/526631/2 "2010-01-27T06:21:27Z")
No, unless you count Ceres. It was once popular to think that the asteroid belt was the remains of a planet that got somehow destroyed, but all of the asteroids combined would mass less than Pluto. The current consensus is that the entire Solar System was once something like the asteroid belt, and that while everything else ended up merging into a few planets, the stuff in the belt just never came together to begin with. This is at least partly because Jupiter, in the orbit it’s in, would naturally tend to prevent things from coalescing in that region of space. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [January 27, 2010, 6:36am UTC](https://boards.straightdope.com/t/planets/526631/3 "2010-01-27T06:36:24Z")
Almost certainly not. There was at one time a theory that such a planet existed but was disrupted, with the asteroids as its remnants. This theory has been rejected by virtually every planetological astronomer; only some non-scientists, largely but nto all crackpots, hold it today. (Exception: the ‘Planet V’ hypothesis suggests a possible planet that was thrown into an eccentric orbit about 4 billion years back; the principal justification for this concept is the high incidence of large-object impacts on Earth (and Mars and the Moon) attributed to that time period. It is not considered likely by most competent scholars but at least has more rational support than the discarded and crackpot theories.) For the record: 1. Phaeton was the name assigned the hypothetical Asteroid Belt planet when that theory had some popular support. 2. Ceres, the largest and first-discovered asteroid, was for a short time thought to be the fifth planet. 3. Opalcat will have to live with a two-point list; there are no other salient points I can think of to make on the topic. ETA: What **Chronos** said. ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [January 27, 2010, 3:26pm UTC](https://boards.straightdope.com/t/planets/526631/4 "2010-01-27T15:26:00Z")
Velikovsky’s theories suggested that there was. 😃 ---
**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:** [January 27, 2010, 3:35pm UTC](https://boards.straightdope.com/t/planets/526631/5 "2010-01-27T15:35:15Z")
For 38 years (1807-1845) there were 4 planets between Jupiter and Mars (1 Ceres, 2 Pallas, 3 Juno, and 4 Vesta). It was with the discovery of 5 Astraea that: > [@](#): > > it became apparent that these four were only the largest of a whole new type of celestial body. > **[5 Astraea](https://en.wikipedia.org/wiki/5_Astraea)** > > 5 Astraea (/æˈstriːə/) is an asteroid in the asteroid belt. This object is orbiting the Sun at a distance of 385 million kilometres (2.5735 AU) with a period of 4.13 yr and an orbital eccentricity of 0.19. The orbital plane is inclined at an angle of 5.37° to the plane of the ecliptic. It is spinning with a period of 16.8 h. The surface of Astraea is highly reflective and its composition is probably a mixture of nickel–iron with silicates of magnesium and iron. It is an S-type asteroid in the Tho... So those 4 planets were demoted around 1845. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 27, 2010, 3:37pm UTC](https://boards.straightdope.com/t/planets/526631/6 "2010-01-27T15:37:42Z")
Lotsa science fiction stories use the idea, because it’s irresistible (Heinlein’s **Stranger in a Strange land** and James Hogan’s _Giants_ series, to name two examples), but the idea has been discredited for a long time. But it fits so nicely into the Titius-Bode-Blagg-Richardson law. ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [January 27, 2010, 3:49pm UTC](https://boards.straightdope.com/t/planets/526631/7 "2010-01-27T15:49:52Z")
Ceres is now classified as a dwarf planet. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [January 27, 2010, 5:33pm UTC](https://boards.straightdope.com/t/planets/526631/8 "2010-01-27T17:33:45Z")
> [@Anne\_Neville](#): > > Ceres is now classified as a dwarf planet. Cool! Can we travel there and meet them? 🙂