# Planet with 3 suns!



## Rane Longfox (Jul 15, 2005)

http://www.cnn.com/2005/TECH/space/07/14/planet.suns.reut/index.html

Like... wow!


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## Jayaprakash Satyamurthy (Jul 15, 2005)

Seriously. More than Tatooine, I was reminded of the world of Marune, in Jack Vance's Marune: Alastor 933. The planet has three suns, each of which casts a different colour of light. The people in Marune order their lives according to a strict time-table based on the varieties of light provided by the suns singly or in various combinations. It's wonderful how the universe makes even the most far-fetched of sf writer's astronomical speculations come ture, somewhere or the other!


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## Leto (Jul 15, 2005)

However, this one is a gas planet. It could have been a four-sun system aborted.

If it was a terran-like, give me the sun block and I'll be ready to move.


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## Eradius Lore (Jul 15, 2005)

very cool, three suns! they must have hot summers, tatooine planets is a good name for it btw


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## Stalker (Jul 15, 2005)

Triple stars as scientists think fit  life very little because of higher instability of such a system. However, I remember _Cicle of Fire_ by *Hal Clement* where he researches the possibility of life in double (?) system and constructs two forms of life each of them accustomed to the separate astronomic cycle (aphelion and perihelion of the 2nd component of the system). As far as I remember (correct me if I mistaken because I read the book 20 years ago) there were 2 different species co-inhabiting the planet. We may also suppose that the same species may undergo metamorphosis in order to survive critical climatic change or cyclically give birth to a generation fitting the changed conditions.


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## Jayaprakash Satyamurthy (Jul 15, 2005)

Hal Clement is one author I've been rather remiss in exploring - I do have a copy of his classic *Mission of Gravity*, but it has lain unread on my shelf for nearly a year now. I must remember to remedy that sometime soon - all this planetary speculation is fun, and it's been a while since I've indulged, diverted as I've been into more fantastic by-lanes lately.


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## Stalker (Jul 15, 2005)

I would call Hal Clement an orthodox sci-fi writer. His benefit is that he always researches thoroughly the effects of the worlds he creates.


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## Brian G Turner (Jul 15, 2005)

I've written about a triple-star system as well in my main aspiring works - I think the biggest surprise would be if there weren't any.

The current level of understanding regarding plantary formation in science is just appalling.


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## zorcarepublic (Jul 15, 2005)

Cool...

Right, my setting in a three-star system doesn't sound so stupid now...

(well, its really a binary system (long-range, distance between stars is from sun to pluto) with a brown dwarf orbiting one of the stars around where Earth would be)


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## GOLLUM (Jul 15, 2005)

Looks like a great place to open a new bar.... 

That's amazing stuff Cal glad you posted this one.....


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## Rane Longfox (Jul 15, 2005)

Beat the Costa del Sol any day

But yes, the lack of knowledge about planetary formation is quite shocking. I had always thought it was accepted knowledge that a planet such as this one was impossible


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## Brian G Turner (Jul 15, 2005)

I thought it was equally common sense that it would be quite possible - just more complex mechanics.


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## Rane Longfox (Jul 16, 2005)

True I guess... the gravity would be quite complicated though, wouldn't it. Must be very rare.


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## PERCON (Jul 22, 2005)

A 3 sun system seems perfectly acceptable to me, if the planet orbits just one of the 3 suns then the gravitational pull from the other two may only affect it slightly or not at all meaning it is the same as our solar system in a way. The mechanics of a 3 sun system could become complex but visualising it is quite easy and so the idea is straight forward when you think about it and can picture the relationships between suns and planet.

However, what if a planet in a different system was being pulled by 3 suns equally and the suns were spread out at equal distances from one another, would the planet spin in it's own circle orbiting nothing?? 

Just wondering...  

_PERCON_


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## Brian G Turner (Jul 22, 2005)

The mechanics I believe would be pretty complex - if I recall, the "three body problem" is a classic chaos scenario in physics regarding gravity. Doesn't mean to say it's not possible, though.


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## The Master™ (Jul 22, 2005)

I would have thought that the gravitaional forces exerted by 3 suns would be enormous and any life-bearing planets would be impossible... They'd mostly be burnt out rocks or gas giants...


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## Stalker (Jul 22, 2005)

You understand the problem a little bit wrongly, PERCON. Simply replace Jupiter and, well Pluto with the stars - that's it! In triple system one star is always a main component - all the rest go their orbits around it, and the orbits may be very long, and even not lie in ecliptic. 
Gravitation? Generally agreeing with the Master, I should also admit that the gravitational force will depend upon the distances. Remember Newton: the force weakens in quadratic progression. Opportunities for life due to dramatic changes in gravitational forces and sources of radiation remain very narrow though.


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## The Master™ (Jul 22, 2005)

I might sound really daft here, but I need to ask... If there are three suns... who orbits who??? AND if it is a planetary star system with tertiary - or is it trinary(or even binary) stars, how do they orbit???


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## Stalker (Jul 22, 2005)

Well, the point here is distances. 

The simplest (and more stable) example is when two subordinate components revolve around the main component of tertiary system. As I said above, in order to fix it in your imagination just substitute two giant-planets with two more suns, then just arithmetically expand the distances between them, and you will get more or less stable tertiary solar system. Jupiter and Saturn, and Uran etc. have their sattelites. All right, Jupiter transforms into sun ten times as bigger, move his orbit 50 astronomic units farther, enlarge his sattelites and expand their orbits in the same way, and you'll get a star-component with the planetary sistem of its own, and the main component ill also have its rock planets along with the sun orbiting in the same ecliptic, the add the third component in the same way. Rough example but it should work. Sirius is the example of such a triple system. Got it?
Less stable tertiary system is when the third component orbits around the second component that, in its turn, orbits the main component...


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## The Master™ (Jul 22, 2005)

Thanks for that info, now I understand it...


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## GOLLUM (Oct 1, 2005)

Thanks for the update Stalker....


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## ommigosh (Oct 2, 2005)

Good explanation Stalker, thanks.

I think I saac Asimov wrote a classic science fiction story called Nightfall about a planet with multiple suns.  It was always daylight there apart from every few thousand years or so when the suns all fell below the horizon together causing mass panic, riots and the sudden collapse of civilisation.. A good idea for a story, and I always trusted that Asimov was probably a good enough scientist to have worked out if such an arrangement of suns was possible.


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## Arkangel (Oct 5, 2005)

Stalker, I have a question. Wont the gravitational pull of one sun affect the other. Eventually one as to win over the other or their mass have to be identical. If it is a elliptical orbit wont the gravity pull of the bigger mass star be more at the closest point between the 2 and the one with higher mass pull on the other. If they have to be stable shouldnt they have a circular orbit.


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## dreamwalker (Oct 6, 2005)

Arkangel said:
			
		

> Stalker, I have a question. Wont the gravitational pull of one sun affect the other. Eventually one as to win over the other or their mass have to be identical. If it is a elliptical orbit wont the gravity pull of the bigger mass star be more at the closest point between the 2 and the one with higher mass pull on the other. If they have to be stable shouldnt they have a circular orbit.


Thats like 4 questions!



			
				Arkangel said:
			
		

> Wont the gravitational pull of one sun affect the other. Eventually one as to win over the other or their mass have to be identical.


This could happen but it's much more complicated than that. Let me explain.
If a red giant was orbiting a neutron star - (a big massive marshmellow of a star orbiting a tiny lead ball) in a very tight orbit close enough for the neutron stars gavity well to be greater than the force of gravity near the surface of the red giant, then matter may transfer from one star to another. but this would cause problems, because nuetron stars burn different fuel at a different rate to a red giant. Either star could become unstable and there orbits could become unstable. One star could nova, or the red giant could super nova. the Nuetron star could (and most probably over time) turn into a black hole as there super dense already. But the key for that to happen is that one star has to be dense and the other has to be puffy.



			
				Arkangel said:
			
		

> If it is a elliptical orbit wont the gravity pull of the bigger mass star be more at the closest point between the 2 and the one with higher mass pull on the other.


Not sure on exactly what you where trying to say but...
Its the same away jupiter doesn't effect the Earths orbit. Elliptical or not. In a complete cycle there'll always be farest from and closest too distance and the (comparitivly weak) gavitiational forces will be ballanced because the whole thing is in a closed system. It would take something from out of the closed system to upset the balance, eg rouge planetoid from outsie the star system to upset the gavitational balance.


			
				Arkangel said:
			
		

> If they have to be stable shouldnt they have a circular orbit.


No. -  Stable means the orbits don't degrade after some time. Comets like haleys have highly elliptical orbits but are (almost - they keep losing mass) in stable orbit. So is pluto - its in a very elliptical orbit considering its a planet.
After 5 billion years, you can be pretty much certain that everything you see in the solar system is in a stable orbit - so far as to say it hasn't escaped the solar system or been swallowed up.


About gravitational fields. It works on (nearly) the inverse square rule. Which means, on the surface of earth gravity is 1, travel 2 away from it and gravity will be a quarter, travel 5 away from it, gravity will be a 25th. So you need to be relativily close for gravity to grab you! Conversly, you'll never be out of the gravitational effect of an object no matter how far away you are.


Another thing. Were the common orbit center is close to the center of the largest star;
If they where near equal and the orbits stable, then there orbits center would be inbetween all three stars, and there orbits would never be the same twice. Its long been said that when there are 3 or more objects in an orbit, it becomes impossible to calculate any exact figure in relation to there orbits.

(I used to play astronaut)


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## Arkangel (Oct 6, 2005)

Thanks for answering dreamwalker


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## Stalker (Oct 6, 2005)

dreamwalker said:
			
		

> but this would cause problems, because nuetron stars burn different fuel at a different rate to a red giant.


AFAIK, neutron stars don't burn at all, they are the product of incomplete collupse of the star that has exhausted its fuel, so intertal outward pressure cannot balance its gravitational inward pull but gravitation is not enough to transform them into black holes. Such neutron star does not emit any rays, at least, in visible diapason. But, you are right such examples of neutron star-giant were observed, and astronomers fixed pumping the substance from the unfortunate giant that appeared to orbit the main component too close by to the neutron star.
To another point, well... if I understand you right, you are talking about prolonged elliptical orbits. In this case, yeah, such an orbit is more unstable that that one which approaches more rounded ellipse.
On all other points I agree completely with dreamwalker.


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## dreamwalker (Oct 6, 2005)

^^Yeah the nuetron star was just one example (poor one now I realise it) of a small super dense object that wasn't a black hole. I probably have to reseach whether they burn with nuclear fusion or not but im pretty certain some energy is emmited or else it would collapse and form a black whole due to density issuses.

As for orbits. My general understanding is...
It goes around = stable
It sprials = its unstable
the inverse square law that governs gravity allows stablity in orbits to be suprisingly easy although in reality, no orbit is truely stable over forever due to stellar friction and objects losing and againing mass- even within a closed system. 
But hey astronomys all about sitting on your ass generalising anyway so!


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