If Uranus’ inclination is in fact due to an impact with something else, the impactor was probably itself orbiting more or less in the ecliptic. Compared to the size of the planet, it might have been very off-center (thus causing the inclination change), but compared to the size of the orbit, it wasn’t, so the plane of the orbit wouldn’t have changed much.
Does a planet only get it’s spin (rotation) from the time it formed out of some primordial cloud of hydrogen?
Wouldn’t an object large enough to knock Uranus sideways be big enough to perturb that rotation too? (Does Uranus wobble?)
When we say “knock it sideways”, we do mean perturbing the rotation. The planets are spheres, so the rotation is the only thing that gives them any sort of preferred axis. Likewise, without anything else to give a preferred axis, you don’t get wobbles, either.
I assume Uranus formed from a disk of gas that collapsed due to gravitational attraction, and while doing so, began to have motion. (Spin, or rotation.) Is that correct?
In almost all of the othe planets (I think), this spin is fairly close to the plane of the ecilptic. In the case of Uranus, it is not. Is it likely that Uranus is tilted so far off kilter because of a collision or merger with another object after it’s protoplanetary nebula had collapsed to it’s present volume? (It’s eccentricity and it’s inclination appear average.)
I’m asking because I am wondering if Uranus’s rotation may have already been “set” in place, nearer to the ecliptic, then got pushed over, or did the rotation just form at that angle?
Not sure anyone knows for sure what happened but I cannot see how Uranus would form out of the protoplanetary disk with a rotation like that. I think the most commonly held belief is that something big smashed into it after it had formed and knocked it on its side (in a manner of speaking).
One can imagine scenarios where its angular momentum was skewed drastically some time before it finished coalescing. I don’t know enough about the topic to say how likely such scenarios are, though.
Ok, thanks!
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One can imagine scenarios where its angular momentum was skewed drastically some time before it finished coalescing.
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Ok, thanks!
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For what it’s worth, Uranus’s rings and major moons all orbit in the planet’s equatorial plane, not its orbital plane — which to planetary astronomers suggests that the “Big Tilt” event, whatever that was exactly, probably happened very early in the planet’s history.
I read that, but the implications didn’t sink in. Thanks!