How far off were the Newtownian estimates for orbits?

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willpittenger

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I remember reading that Newton's theory of gravity predicted in correctly the orbits of Mercury, Uranus, and Neptune. Could you describe how big the errors were? It would help if the errors could be stated in AU, planetary diameters, or fractions of the major axis of the orbit. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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vogon13

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Mercury's orbit around the sun 'precesses' 4 arc seconds per <i>century</i> more (IIRC) than Newton allowed.<br /><br />This is roughly half a genital follicle extrusion on a gnat.<br /><br />I am not sure what you are referring to in regards to Uranus and Neptune. Newtons theories were <i>entirely</i> adequate for Voyager II to have <i>successfully</i> reached them in 1986 and 1989 respectively.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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willpittenger

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<blockquote><font class="small">In reply to:</font><hr /><p>I am not sure what you are referring to in regards to Uranus and Neptune. Newtons theories were entirely adequate for Voyager II to have successfully reached them in 1986 and 1989 respectively. <p><hr /></p></p></blockquote><br />All three planets had errors that causes astronomers at the turn of the century to look for more planets. Mercury had astromonmers looking for Vulcan near the Sun (closer than Mercury). Uranus led to Neptune. Those two planets together had Lowell looking for "Planet X". When Clyde Tombaugh fount Pluto, it was much smaller than predicted even if in the correct spot. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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vogon13

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Newtonian math was used entirely for discovery of Neptune and predictions of objects further out.<br /><br />So I still don't know what your getting at.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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vogon13

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The discrepancy in Uranus' orbit (anomalous acceleration until it passed between Neptune, then undiscovered, and sun and then anomalous deceleration afterwards) was put through the Newtonian math backwards (so to speak) to generate an orbit and masss for the unknown body.<br /><br />Your 'drift' implies Newtonian methods 'fail' at Neptune when in fact, it is one of it's greatest triumphs.<br /><br />That Adams and Leverrier came up with such similar predictions using the same 'software' (so to speak) is also a great endorsement of the scientific method. <br /><br />When is the last time 2 psychics (or prophets, for that matter) came up independently with the same thing?<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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vogon13

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Lowell made a mistake?<br /><br />'Residuals' of Neptune's orbit small in Lowell's day, and after Voyager II's extremely accurate and successful flyby even smaller now.<br /><br />Seems Voyager 'corrected' value for Neptune's mass 1/4% (IIRC) and 'the books balance' now.<br /><br />Back on Mercury, the tiny discrepency in it's orbit was explained by Einstien. The suns gravity represents a large amount of energy. Energy and mass are equivalent per the famous equation E=MC2. Converting the gravitational energy to mass, adding it to the suns mass, and then recalculating Mercury's orbit the 'old fashioned' Newtonian way comes out correct. <br /><br />It turns out a gravitational field has a gravitational field of its own, weird, huh?<br /><br /><br />Newton twern't wrong, just incomplete.<br /><br /><br />(I have grossly simplified things here, but the gist of it is reasonably close, btw)<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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CalliArcale

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He was wrong on the orbit too, actually. He found Pluto by pure luck; it just happened to be where he expected the ninth planet to be.<br /><br />The error was not Newton's fault. The error was a result of inaccurate measurements. As the data became better, the unexplained deviations in Neptune's orbit disappeared. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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