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Metamorphium
2004-Jul-13, 11:35 AM
Hi all,

first things first. This site and especially "The Bad Astronomer" brought me to much deeper interest in Astronomy than I would ever imagine. Thank you Phil for this. Thanks goes also to everyone keeping this place very special. I have to admit though that the book IS very dangerous. Since I read the most in public transportations my uncontrollable bursts of laughter made my neighbors wonder about my mental health. Such a great book. Well enough of that.

I have a pretty weird question to ask:

Imagine the following hypothetical situation. You have a solar system which consisted of two suns placed from each other in some distance. You have also a few planets orbiting them. My question is if there is a possibility (some very weird mass consequence) that the planets will orbit not in a circle or elipse but as an 8 around these suns. This would mean that when the planet goes around the first star, it would be taken over by the gravity field of the second sun. For this idea to work it would be probably necessary for both stars to have very similar weight and other really unbelievable conditions.

Yet I need to know if this could ever happen.

Thanks a lot for explaining why this is not possible at all. :D

Yorkshireman
2004-Jul-13, 11:57 AM
Welcome to the board, Metamorphium.

I think a figure-8 orbit would be possible, but I very much doubt it would be stable for more than a handful of orbits. The 'crossing point' from sun A to sun B would be an area of very weak resultant gravity, and so any other disturbance (i.e any other nearby planets, or even other nearby stars) would tug it out of alignment pretty fast. Anyone else here willing to run a simulation?

Rob.

Moose
2004-Jul-13, 12:43 PM
Phil talks about orbits in binary systems in his phantom menace review here (http://www.badastronomy.com/bad/movies/starwars2.html). (About midway down the page.)

bigsplit
2004-Jul-13, 04:09 PM
Hi all,

first things first. This site and especially "The Bad Astronomer" brought me to much deeper interest in Astronomy than I would ever imagine. Thank you Phil for this. Thanks goes also to everyone keeping this place very special. I have to admit though that the book IS very dangerous. Since I read the most in public transportations my uncontrollable bursts of laughter made my neighbors wonder about my mental health. Such a great book. Well enough of that.

I have a pretty weird question to ask:

Imagine the following hypothetical situation. You have a solar system which consisted of two suns placed from each other in some distance. You have also a few planets orbiting them. My question is if there is a possibility (some very weird mass consequence) that the planets will orbit not in a circle or elipse but as an 8 around these suns. This would mean that when the planet goes around the first star, it would be taken over by the gravity field of the second sun. For this idea to work it would be probably necessary for both stars to have very similar weight and other really unbelievable conditions.

Yet I need to know if this could ever happen.

Thanks a lot for explaining why this is not possible at all. :D

I would not think it is possible for planet to do this. Planets have stable orbits, if they do not they do not stay planets very long. If the planets did revolve around both suns with stability, they would have to revolve around the center of gravity between both Suns, which would be somewhere between the two. If the Sun/Sun were to get a grip and pull the planet between it self and one of the suns it would swing back around towards the opposite sun and either settle into an orbit inside the Suns, crash into the opposite sun or move outside the sun, drifting off until the Sun/Sun system recaptures it.

But, I may be wrong.

tlbs101
2004-Jul-13, 08:54 PM
That kind of orbit is typical in Chaotic systems. The stars would not act as points for predictable Keplerian orbits, but they would act as attractors in Chaotic space (mathematical space). The exact location of the planet would not be very predictible, orbit-to-orbit, but the planet could draw out a figure-8 every time.

This is just a possibility.

Metamorphium
2004-Jul-13, 09:13 PM
Thanks for the info. This implies that if this planet had an 8 orbit, it would be only temporary. This helped me a lot since I can use this idea to justify some anomalies.

Thanks again :)