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2011/10/07

Uranus got double-tapped? | Bad Astronomy

(For Urantia Book explanation see bottom. Urantia Book said our solar system came from big bang nebula Andronover 875 billion years ago, created our sun star Monmatia. Then 4.5 billion years ago came closer  the Angona system which drew parts of the sun and created solar system today.)
Uranus got double-tapped? | Bad Astronomy:
One of the enduring mysteries of our solar system is why Uranus is tilted over on its side. If you measure the angle of a planet’s rotation axis (the location of its north pole) compared to the plane of its orbit, you find that all the planets in the solar system are tipped. Jupiter is only 3°, but Earth is at a healthy 23° angle; Mars is too. Venus is tipped so far over it’s essentially upside-down (we know this because it spins the wrong way).
Uranus, weirdly, is at 98°, like it’s rolling around the outer solar system on its side. The best guess is that it got hit hard by something planet-sized long ago, knocking it over (though there are other, more speculative, ideas). The problem with that is that its moons and rings all orbit around its equator, meaning their orbital planes are tipped as well. It’s hard to see how that might have happened, even if you assume the moons formed in that collision (as, apparently, our Moon formed in an ancient grazing impact with Earth by a Mars-sized body).



Well, a team of astronomers have come up with a new idea: maybe Uranus wasn’t hit by one big object. Maybe it was hit by two smaller ones.



It would’ve happened when the planet was still forming, and surrounded by a disk of leftover material that was in the process of forming its moons. A proto-planet could’ve hit it, knocking it over somewhat, and sending up a vast cloud of debris that puffed the disk up into a torus (that’s what us scientist-types call a donut). A second collision some time later would’ve completed the task. After more time elapsed things settled down and Uranus would’ve been rotating sideways, and the torus would’ve flattened back into a disk aligned with Uranus’ equator due to tidal forces.

It’s an interesting, if surprising idea. If there were only one collision at that time, the astronomers found the dynamics would’ve made the moons orbit the planet the wrong way (retrograde, against the spin of the planet). It would’ve taken a second hit to add enough momentum to the debris disk to get the moons orbiting prograde.

I wonder if this would also somehow explain the weird magnetic field of Uranus. It’s not aligned at all with the rotation axis, and is even off-center from the core of the planet! It’s unclear why this might be, though it may have to do with Uranus being an ice giant (PDF), with a different composition and structure than Jupiter and Saturn, the two gas giants. I’ll note Earth’s magnetic field isn’t well aligned with our spin axis either, but at least it has the courtesy to be centered on the center of our planet! One idea I’ve seen is that the magnetic field of Uranus isn’t generated in its core, like ours is (or, to be more accurate, in the outer layer of our core — this stuff gets complicated pretty quickly), but might be created higher up in the interior. Clearly, there’s a lot left to figure out here.

All of these things are clues to Uranus’ origin and evolution, its history. The characteristics we see today had some cause, and by piecing all this together we can, perhaps, understand the story of this giant planet. And we need to sometimes entertain unusual ideas — as long as the science supports them — because if there’s one thing that’s usual about the bodies inhabiting the solar system, it’s that they’re unusual.

Image credit: Erich Karkoschka (University of Arizona) and NASA






Related posts:

- Did Herschel see the rings of Uranus?

- Ooo-RAN-us

- Yes, yes, rings around Uranus, haha

- A new ring around Uranus (and this followup)



URANTIA BOOK about Angona System who came and affected our solar system, some 4,500,000,000 years ago, created planets such as Jupiter, Saturn, Uranus etc.


P.465 -§6 Some of the variable stars, in or near the state of maximum pulsation, are in process of giving origin to subsidiary systems, many of which will eventually be much like your own sun and its revolving planets. Your sun was in just such a state of mighty pulsation when the massive Angona system swung into near approach, and the outer surface of the sun began to erupt veritable streams--
P.655 - §9 4,500,000,000 years ago the enormous Angona system began its approach to the neighborhood of this solitary sun. The center of this great system was a dark giant of space, solid, highly charged, and possessing tremendous gravity pull.
P.656 - §1 As Angona more closely approached the sun, at moments of maximum expansion during solar pulsations, streams of gaseous material were shot out into space as gigantic solar tongues. At first these flaming gas tongues would invariably fall back into the sun, but as Angona drew nearer and nearer, the gravity pull of the gigantic visitor became so great that these tongues of gas would break off at certain points, the roots falling back into the sun while the outer sections would become detached to form independent bodies of matter, solar meteorites, which immediately started to revolve about the sun in elliptical orbits of their own.
P.656 - §2 As the Angona system drew nearer, the solar extrusions grew larger and larger; more and more matter was drawn from the sun to become independent circulating bodies in surrounding space. This situation developed for about five hundred thousand years until Angona made its closest approach to the sun; whereupon the sun, in conjunction with one of its periodic internal convulsions, experienced a partial disruption; from opposite sides and simultaneously, enormous volumes of matter were disgorged. From the Angona side there was drawn out a vast column of solar gases, rather pointed at both ends and markedly bulging at the center, which became permanently detached from the immediate gravity control of the sun.
P.656 - §3 This great column of solar gases which was thus separated from the sun subsequently evolved into the twelve planets of the solar system. The repercussional ejection of gas from the opposite side of the sun in tidal sympathy with the extrusion of this gigantic solar system ancestor, has since condensed into the meteors and space dust of the solar system, although much, very much, of this matter was subsequently recaptured by solar gravity as the Angona system receded into remote space.
P.656 - §4 Although Angona succeeded in drawing away the ancestral material of the solar system planets and the enormous volume of matter now circulating about the sun as asteroids and meteors, it did not secure for itself any of this solar matter. The visiting system did not come quite close enough to actually steal any of the sun's substance, but it did swing sufficiently close to draw off into the intervening space all of the material comprising the present-day solar system.
P.656 - §5 The five inner and five outer planets soon formed in miniature from the cooling and condensing nucleuses in the less massive and tapering ends of the gigantic gravity bulge which Angona had succeeded in detaching from the sun, while Saturn and Jupiter were formed from the more massive and bulging central portions. The powerful gravity pull of Jupiter and Saturn early captured most of the material stolen from Angona as the retrograde motion of certain of their satellites bears witness.
P.657 - §1 The planets do not swing around the sun in the equatorial plane of their solar mother, which they would do if they had been thrown off by solar revolution. Rather, they travel in the plane of the Angona solar extrusion, which existed at a considerable angle to the plane of the sun's equator.
P.657 - §2 While Angona was unable to capture any of the solar mass, your sun did add to its metamorphosing planetary family some of the circulating space material of the visiting system. Due to the intense gravity field of Angona, its tributary planetary family pursued orbits of considerable distance from the dark giant; and shortly after the extrusion of the solar system ancestral mass and while Angona was yet in the vicinity of the sun, three of the major planets of the Angona system swung so near to the massive solar system ancestor that its gravitational pull, augmented by that of the sun, was sufficient to overbalance the gravity grasp of Angona and to permanently detach these three tributaries of the celestial wanderer.
P.657 - §3 All of the solar system material derived from the sun was originally endowed with a homogeneous direction of orbital swing, and had it not been for the intrusion of these three foreign space bodies, all solar system material would still maintain the same direction of orbital movement. As it was, the impact of the three Angona tributaries injected new and foreign directional forces into the emerging solar system with the resultant appearance of retrograde motion. Retrograde motion in any astronomic system is always accidental and always appears as a result of the collisional impact of foreign space bodies. Such collisions may not always produce retrograde motion, but no retrograde ever appears except in a system containing masses which have diverse origins.

057. The Origin of Urantia . Life Carrier
058. Life Establishment on Urantia

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