10-05-01, 10:19 PM
A friend of mine is writing a fantasy story. She asked me if, with a basic knowledge of physics (and specifically, gravitation) it would be possible to have a world with two equators... equators, meaning this planet would have two suns with some oddball orbital pattern.
Is such a thing at all possible?
And, please, don't say, "Well, if it's a fantasy story, you can bend the rules." The best fantasy stories are those based in reality. Besides, it'd be sidestepping the question.
You would have two equators in the solar sense, yes, but in order for an equator to be useful as a point of reference, you can only have one. The other one would be called something else (like Prime Meridian) to make things easier.
It's not fantasy, and since there are trillions of binary systems in the universe, there are trillions of planets where this will take place.
10-24-01, 03:37 AM
The equator of a planet is usually defined by its spin. The equatorial plane is perpendicular to the spin axis.
In a binary star system, it would be quite possible for the two stars to appear to orbit around different great circles of a planet. However, the planet can only spin around one axis at a time, so it will still have only one equator.
10-24-01, 10:46 AM
Well, the way a binary star system would work, I think that both stars would be in the plane of the planet that is orbiting them, since all of the components of a system orbit the center of mass. This would, however, result in some very bizzare seasons, I would think. Also, one star is usually bigger than the other, in the pair, so there would be the interesting color differences as one star gets closer and further, as well as the vegetation... they'd have very different cycles.