Paulibus
- 203
- 11
. There's a bit of confusion here. In an empty model universe the orbits for two masses attracted to each other by gravity are always "planar" and "axial; relative motion then lies in a plane defined by two lines: one joining the two masses and the other along their relative velocity as seen by any observer (assuming the two lines to not be collinear). You might say that a lump traveling in any direction "it wishes" orbits a central attracting mass it encounters in a plane determined by what this "wish" was when they first met and began perceptibly to gravitate, but this is a bit wooly, don't you think?Codex34 said:Can gravity form non-axial rotations such that any stars, planets and moons do not rotate in planar orbits but orbit in any orbital direction they wish?
Random axial rotation would be logical only if one took a large enough average over many independently-formed systems. Logical in the case of planetary systems formed by gravitational collapse in different parts of a galaxy, yes. But not in planet formation in say, our solar system. Henry Ford was wrong: history is not bunk, and planetary formation initiated by gravitational shear in a single rotating disc is a process with a shared history.Chronos said:Random axial rotation would be a logical conclusion. Have you examples to the contrary? Shear only affects the process of collapse.
Don't most of our planets rotate (roughly -- ignore their seasons) in the same sense (clockwise or anticlockwise) if viewed from a distance, along the ecliptic axis? With their moons? I'll check. If so, that's your example. Just remember, shear and gravity go together, like a horse and carriage.