"Pluto is dead" - Mike Brown, It's official |
"Pluto is dead" - Mike Brown, It's official |
Aug 24 2006, 01:58 PM
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#1
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Member Group: Members Posts: 531 Joined: 24-August 05 Member No.: 471 |
-------------------- - blue_scape / Nico -
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Aug 31 2006, 01:54 PM
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#2
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Senior Member Group: Members Posts: 1018 Joined: 29-November 05 From: Seattle, WA, USA Member No.: 590 |
Uranus and Saturn are both in less eccentric orbits than Mars. I've never heard anyone suggest that they used to be in more elliptical orbits. I HAVE heard the suggestion that they both formed further in and have gradually drifted further out, but that would have happened when the Solar System was new.
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Aug 31 2006, 06:07 PM
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#3
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Member Group: Members Posts: 147 Joined: 14-April 06 From: Berlin Member No.: 744 |
Uranus and Saturn are both in less eccentric orbits than Mars. I've never heard anyone suggest that they used to be in more elliptical orbits. I HAVE heard the suggestion that they both formed further in and have gradually drifted further out, but that would have happened when the Solar System was new. Well, it basically goes like this: "Jupiter and Saturn start out at roughly 5 and 8 astronomical units; Uranus and Neptune begin much closer to the Sun than their current positions, at about 13 and 14 AU. They stay pretty comfortably in those positions for about 100,000 years. Then, quite suddenly, that 1:2 resonance is reached. Saturn and Jupiter don't change a lot initially, but the orbits of Uranus and Neptune go nuts. They get much more eccentric, so that their orbits cross; at times Uranus even gets very close to Saturn. After about a million years, the eccentricity dies down, and Uranus and Neptune are on their way out to more distant positions in the solar system, at the same time that Saturn begins to acquire its present orbit eccentricity." The Whole Article -------------------- |
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Aug 31 2006, 06:42 PM
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#4
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
"Jupiter and Saturn start out at roughly 5 and 8 astronomical units; Uranus and Neptune begin much closer to the Sun than their current positions, at about 13 and 14 AU. I have a problem with that scenario. Namely, Saturn, Uranus and Neptune start closer in than they're now. * Saturn : 8 AU --> 9.5 AU * Uranus : 13 AU --> 19 AU * Neptune : 14 AU --> 30 AU All three are gaining momentum as they move into a higher orbit. Who's losing momentum here? You can't just get it out of nothing. There has to be a pretty large object that spirals inward as a consequence. I see Jupiter stayed pretty much where it is now so no luck there. -------------------- |
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