Measuring sun's true direction

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21 years 8 months ago #4631 by tvanflandern
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>How do we know (measure) the sun's true 'graviton' direction or true direction that the sun is pulling the earth from?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

Think of the other inner planets as signposts at known locations fixed in space relative to the Sun. Then we on Earth need only bounce radar signals off each signpost to see how far we are from it and how fast we are moving relative to it. We can then figure out exactly what direction and speed the Earth has at each moment as it orbits.

The real inner planets move, of course. But the principle is the same because we know their orbits so well.

Once we know the Earth's precise motion (a curved path called its orbit), a simple calculation gives the direction of the acceleration that produces that curvature. (We calculate the direction of the "radius of curvature", for those who know what that means.) We can then compare the direction of Earth's acceleration with the direction of the apparent Sun and the direction of the true Sun. Earth's real acceleration happens to be toward the latter direction.

<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>If possible in lame men terms so I could also understand it. <img src=icon_smile_wink.gif border=0 align=middle><hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

You probably didn't intend this pun, but it is a good one. The English expression is "laymen". Look up the definitions of both. <img src=icon_smile_big.gif border=0 align=middle> -|Tom|-


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21 years 8 months ago #3616 by Rudolf
Replied by Rudolf on topic Reply from Rudolf Henning
Thanks, sorry for the typo. Hopefully I'm not lame...

Because the Earth's orbit is not a perfect circle this amount of diviation between the graviton and photon directions must change during the course of the orbit - I assume. Any ideas what the maximum and minimum values are?
This could in another way be a proof that the speed of gravity is not c because the orbital velocity will be different.

Rudolf

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21 years 8 months ago #4768 by Larry Burford
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Rudolf]
If possible in lame men terms so I could also understand it.
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
[tvf]
You probably didn't intend this pun, but it is a good one. The English expression is "laymen". Look up the definitions of both. -|Tom|-<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
[Rudolf]
Thanks, sorry for the typo. Hopefully I'm not lame...
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
I love puns, and this is one of the best I've seen in a long time.

Thanks,
LB

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21 years 8 months ago #2798 by tvanflandern
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>Because the Earth's orbit is not a perfect circle this amount of diviation between the graviton and photon directions must change during the course of the orbit - I assume. Any ideas what the maximum and minimum values are?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

The average difference is about 20.5 arc seconds. Because of Earth's eccentricity, that angle increases and decreases during the year by about 0.7 arc seconds. That variation is easily within the range of detection, and has been long known to exist in the observations. -|Tom|-


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21 years 8 months ago #3312 by Jim
Replied by Jim on topic Reply from
How does the gravity of Jupiter effect the odservation? If the sun/Jupiter system is moving both bodies wouldn't the sun's mass center be offset from the system's gravity center?

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21 years 8 months ago #4771 by tvanflandern
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>How does the gravity of Jupiter effect the observation? If the sun/Jupiter system is moving both bodies wouldn't the sun's mass center be offset from the system's gravity center?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

Perturbations by all the planets affect the Sun and the Earth in different ways. All this is both observed and included in the calculations used to compare with observations.

As a first approximation, Jupiter pulls both Sun and Earth off to one side of the so-called "barycenter" (an unseen stationary point), causing Earth and Sun to circle one another in the short term (yearly) but to circle the barycenter in the long term (12 years or more). -|Tom|-

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