# a planet with multiple suns? **URL:** \ **Category:** Factual Questions\ **Created:** [August 4, 2002, 7:41am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281 "2002-08-04T07:41:08Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Kevin\_Partida](https://avatars.discourse-cdn.com/v4/letter/k/b4bc9f/32.png) [@Kevin\_Partida](https://boards.straightdope.com/u/Kevin_Partida)\ **Post date:** [August 4, 2002, 7:41am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/1 "2002-08-04T07:41:08Z")
Ok, I know that there are planets with multiple moons orbiting around them. Now then, I am wondering if there is the possibility of a planet having 2, 3, or even 4 stars close enough to it that they could emit enough light for the planet to always be in a state of daylight (considering the stars were all positioned correctly). I know that the planet would have to be orbiting only one star (I assume). Can stars be close enough together to produce an affect that is similar to having multiple suns? ---
**Author:** ![taklon](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@taklon](https://boards.straightdope.com/u/taklon)\ **Post date:** [August 4, 2002, 11:45am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/2 "2002-08-04T11:45:58Z")
Apparently most star systems are binary systems, so i don’t see it couldn’t light a planet orbiting one star. Might not be anyone there to see it though. ---
**Author:** ![AV8R](https://avatars.discourse-cdn.com/v4/letter/a/898d66/32.png) [@AV8R](https://boards.straightdope.com/u/AV8R)\ **Post date:** [August 4, 2002, 12:26pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/3 "2002-08-04T12:26:49Z")
Let me be the first to recommend the short story _ **Nightfall** _ by Isaac Asimov. The story tells of a civilization that lives on a planet in a system of 6 suns. The inhabitants only experience nightfall about once every 2000 years. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [August 4, 2002, 12:45pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/4 "2002-08-04T12:45:26Z")
. This thread makes me homesick. 😉 😃 ---
**Author:** ![Improv\_Geek](https://avatars.discourse-cdn.com/v4/letter/i/b3f665/32.png) [@Improv\_Geek](https://boards.straightdope.com/u/Improv_Geek)\ **Post date:** [August 4, 2002, 12:48pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/5 "2002-08-04T12:48:34Z")
Well as I have the hobby of world creation and language creation I can comment on this. I was on a mailing list filled with physicists and other science big-dogs who debated this for a long time, and as I recall they decided it was possible with a figure 8 orbit, but that it would be incredibly unstable, super unstable. It was one of those “possible, but not going to happen” things. I left the mailing list (which has since gone defunct) because they used to many big words and terms which just threw me for a loop. Hope this helped. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 4, 2002, 1:49pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/6 "2002-08-04T13:49:29Z")
> [@](#): > > In a binary system, a planet must not be located too far away from its “home” star or its orbit will be unstable. If that distance exceeds about one fifth of the closest approach of the other star, then the gravitational pull of that second star can disrupt the orbit of the planet. [http://www.solstation.com/stars/alp-cent3.htm](http://www.solstation.com/stars/alp-cent3.htm) ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [August 4, 2002, 4:37pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/7 "2002-08-04T16:37:29Z")
Or you can have a planet rotate around the common centre of a binary star system. ---
**Author:** ![AHunter3](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ahunter3/32/368_2.png) [@AHunter3](https://boards.straightdope.com/u/AHunter3)\ **Post date:** [August 4, 2002, 4:45pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/8 "2002-08-04T16:45:57Z")
Keep in mind that a hypothetical planet orbiting Star#1 exclusively is still going to get enough light to read by (if not necessarily get suntans from) from Stars#2 and #3 if those stars are hot and intense, even if they are pretty far off compared to the star the planet is orbiting. Rigel at 0.8 light year would be one heck of a night light. ---
**Author:** ![The\_Bad\_Astronomer](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@The\_Bad\_Astronomer](https://boards.straightdope.com/u/The_Bad_Astronomer)\ **Post date:** [August 4, 2002, 5:58pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/9 "2002-08-04T17:58:07Z")
I wrote about binary star planets in my review of “Phantom Menace”. It might help: [here is the review](http://www.badastronomy.com/bad/movies/starwars2.html). ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [August 4, 2002, 7:42pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/10 "2002-08-04T19:42:02Z")
The OP did ask about a planet which would always be in daylight. I really don’t think that’s possible with a binary system, and definitely not if it orbits one star, or the center of mass, or it makes a figure-8, or an equilateral triangle. _Nightfall_ notwithstanding, I don’t think it’s even possible to theorize such an orbit in any star system. ---
**Author:** ![taklon](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@taklon](https://boards.straightdope.com/u/taklon)\ **Post date:** [August 4, 2002, 9:20pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/11 "2002-08-04T21:20:27Z")
Or how about a planet that is the center of g in a binary system and stays stationary? The two star orbit around the planet. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [August 4, 2002, 9:38pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/12 "2002-08-04T21:38:47Z")
> [@](#): > > \*Originally posted by taklon \* > \*\*Or how about a planet that is the center of g in a binary system and stays stationary? The two star orbit around the planet. \*\* And while we’re at it, on that planet you can balance a needle on its pointy end. Sounds unlikely the initial conditions required would be possible. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 4, 2002, 10:01pm UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/13 "2002-08-04T22:01:01Z")
Brian Aldiss had a binary system in his Helliconia series; IIRC the planet was in orbit around a star smaller than our sun and this entire solar system was in orbit around a very much larger star; it’s an interesting scenario because you have summer/winter yearly and ‘great summer/winter’ on a much longer cycle but come to think of it, the system might not be terribly workable and would not result in total daylight all of the time. ---
**Author:** ![taklon](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@taklon](https://boards.straightdope.com/u/taklon)\ **Post date:** [August 5, 2002, 12:12am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/14 "2002-08-05T00:12:42Z")
> [@](#): > > \*Originally posted by David Simmons \* > \*\* > > And while we’re at it, on that planet you can balance a needle on its pointy end. > > Sounds unlikely the initial conditions required would be possible. \*\* … and on the head of that pin will be all those angels they keep talking about … 😛 ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [August 5, 2002, 12:17am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/15 "2002-08-05T00:17:34Z")
> [@](#): > > \*Originally posted by taklon \* > \*\*Or how about a planet that is the center of g in a binary system and stays stationary? The two star orbit around the planet. \*\* Gravity would probably tear it apart pretty quickly. ---
**Author:** ![taklon](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@taklon](https://boards.straightdope.com/u/taklon)\ **Post date:** [August 5, 2002, 12:33am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/16 "2002-08-05T00:33:27Z")
> [@](#): > > \*Originally posted by Bosda Di’Chi of Tricor \* > \*\* > > Gravity would probably tear it apart pretty quickly. \*\* two points to remember … (1) I don’t know what I am talking about (2) I’m having a bit of fun (not something I am particularly good at) … mind you if it was at the exact center of g then gravity of the two suns would cancel each other out… right?? then again maybe I don’t realize the gravity of the situation :smack: ---
**Author:** ![Manlob](https://avatars.discourse-cdn.com/v4/letter/m/96bed5/32.png) [@Manlob](https://boards.straightdope.com/u/Manlob)\ **Post date:** [August 5, 2002, 1:55am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/17 "2002-08-05T01:55:51Z")
Start with a planet significantly less mass than star A. Put the planet in a counterclockwise orbit around A with period one year. Take star B which is much more massive than star A, and put the star A + planet system in counterclockwise orbit around B with the distance chosen so that the period is also one year. If the planet started between the stars it will stay in between because both orbits take one year. This gives constant day and should be fairly stable. ---
**Author:** ![Happy\_Lendervedder](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_lendervedder/32/8488_2.png) [@Happy\_Lendervedder](https://boards.straightdope.com/u/Happy_Lendervedder)\ **Post date:** [August 5, 2002, 5:41am UTC](https://boards.straightdope.com/t/a-planet-with-multiple-suns/122281/18 "2002-08-05T05:41:12Z")
> [@](#): > > _Originally posted by ronincyberpunk_ > I left the mailing list (which has since gone defunct) because they used to many big words and terms which just threw me for a loop. > > Hope this helped. Yeah, I was wondering why you left! 🙂 Happy