Why do all the planets orbit the sun horizontally instead of vertically, or at random angles?
In: Physics
Even if the solar system started as a “roundish” cloud of dust, the stars and planets only form when there is some rotation in the dust cloud. Due to conservation of momentum (both linear and angular), random collisions will eventually cause the dust cloud to become a “flat” spinning disk about the axis of rotation. Due to gravitational attraction, any particularly large accretion of dust starts to aggregate more and more material eventually forming the planets and the star at the center. This is why planets typically all orbit in a plane around a star. (occasionally larger stray bodies may be gravitationally captured after the system forms and those bodies may revolve at different angles – many comets, for example, are NOT orbiting our sun on the same plane as the planets)
In many cases, there may be enough material to form more than one star and you get binary systems.
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