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- Larry Burford
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21 years 11 months ago #3617
by Larry Burford
Replied by Larry Burford on topic Reply from Larry Burford
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>... what about the redshift that is not observed in this matter? Since the Earth is in free fall into the gravity field of the sun the redshift is not observed.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
The Earth's orbit is not a perfect circle so we actually do observe a red shift of Sol's light for half of each year and a blue shift for the other half. The size of the shift is not large because the eccentricity of Earth's orbit is not large.
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>If a body was accelerating at .006 m/s^2 and at rest (not in orbit) at 1AU the redshift would be seen and the sun would be seen where it really is.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
If the acceleration results in motion toward Sol then you are actually dealing with blue shift.
The angular displacement of the real and apparent sun will be zero (because orbital velocity is zero), but (a fine detail) now there will be a radial displacement between the real and apparent sun that is not zero (because radial velocity is not zero). As you approach Sol it will appear to be farther away than it really is. I'm not sure if this is measureable at "normal" velocities, though.
Regards,
LB
The Earth's orbit is not a perfect circle so we actually do observe a red shift of Sol's light for half of each year and a blue shift for the other half. The size of the shift is not large because the eccentricity of Earth's orbit is not large.
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>If a body was accelerating at .006 m/s^2 and at rest (not in orbit) at 1AU the redshift would be seen and the sun would be seen where it really is.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
If the acceleration results in motion toward Sol then you are actually dealing with blue shift.
The angular displacement of the real and apparent sun will be zero (because orbital velocity is zero), but (a fine detail) now there will be a radial displacement between the real and apparent sun that is not zero (because radial velocity is not zero). As you approach Sol it will appear to be farther away than it really is. I'm not sure if this is measureable at "normal" velocities, though.
Regards,
LB
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21 years 11 months ago #4252
by Jim
Replied by Jim on topic Reply from
I would love to see the data that shows the red/blue shift cycle for the yearly cycle that you say is oberserved. The radial motion of an accelerating body at a distance of 1AU from the sun is zero if the rate of acceleration is .006ms2.
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21 years 11 months ago #4275
by Larry Burford
Replied by Larry Burford on topic Reply from Larry Burford
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>I would love to see the data that shows the red/blue shift cycle for the yearly cycle that you say is oberserved. The radial motion of an accelerating body at a distance of 1AU from the sun is zero if the rate of acceleration is .006ms2.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Taking the above statement at face value, it sounds like you are pretty sure this is not possible. Forgive me if I'm missing your point, but this is high school Physics.
If the Earth were always 1 AU from the sun then there would be no radial motion.
The Earth, of course, is not always 1 AU from the sun. It varies by plus/minus a percent or two. Peak radial velocity (in both directions) is on the order of 1000 km/hr. Hence the red shift/blue shift cycle.
Regards,
LB
Taking the above statement at face value, it sounds like you are pretty sure this is not possible. Forgive me if I'm missing your point, but this is high school Physics.
If the Earth were always 1 AU from the sun then there would be no radial motion.
The Earth, of course, is not always 1 AU from the sun. It varies by plus/minus a percent or two. Peak radial velocity (in both directions) is on the order of 1000 km/hr. Hence the red shift/blue shift cycle.
Regards,
LB
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21 years 11 months ago #3649
by Jim
Replied by Jim on topic Reply from
I'm not saying this is false, but where is the data that shows this is true? You said it exists or at least suggested that this is true and I just want the data. Thanks for your reply and info about how common this is but I have been seeking this data for quite a long time and it is very important to know exactly.
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21 years 11 months ago #4253
by MarkVitrone
Replied by MarkVitrone on topic Reply from Mark Vitrone
I have been following this thread and am curious along with Jim about this data. Follow me hear for a minute:
If I were looking directly at the sun while in an ideal perfectly circular orbit at 1au, then I should expect that the earth has no radial motion. With radius of 1 au I then expect no red/blue shift correct. However, red/blue shift assumes velocity towards or away from a light emitting body. If the cause of red/blue shift is due to refraction of light through a dense LCM, then a red/blue shift cycle might depend not on variations in distance from sol, but from variance in the density of the LCM at extreme proximity to the sun's surface. If the cycle of shift is not perfect (again, the experiment cited by Larry is vital) then perturbations in the LCM by flares, convections, storms, etc on the sun's suface could cause an effect.
Speculation done:
Cheers and happpy thanksgiving MV
If I were looking directly at the sun while in an ideal perfectly circular orbit at 1au, then I should expect that the earth has no radial motion. With radius of 1 au I then expect no red/blue shift correct. However, red/blue shift assumes velocity towards or away from a light emitting body. If the cause of red/blue shift is due to refraction of light through a dense LCM, then a red/blue shift cycle might depend not on variations in distance from sol, but from variance in the density of the LCM at extreme proximity to the sun's surface. If the cycle of shift is not perfect (again, the experiment cited by Larry is vital) then perturbations in the LCM by flares, convections, storms, etc on the sun's suface could cause an effect.
Speculation done:
Cheers and happpy thanksgiving MV
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21 years 11 months ago #3652
by Larry Burford
Replied by Larry Burford on topic Reply from Larry Burford
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>I'm not saying this is false, but where is the data that shows this is true? You said it exists or at least suggested that this is true and I just want the data. Thanks for your reply and info about how common this is but I have been seeking this data for quite a long time and it is very important to know exactly.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Finding something like that can be pretty hard. I've never actually seen such data, but I know it has to exist because the effect has to exist. And someone, somewhere, has to have measured it. Perhaps Dr Van Flandern can help you with this when he returns.
I just did a quick Google search. I got a lot of hits, but only one that seems to touch on this question. It has a reference to an article that probably contains some data, but might only be an analysis. There is no 'Net link, unfortunately.
I've included some text from that hit. I hope it helps.
It mentions an effect that I had not considered - the rotation of the Earth itself. Obviously this will add to (sunrise) or subtract from (sunset) the Earth's radial velocity and increase or decrease the observed spectral shift.
Hmmm. The sun rotates, too, so it matters where you point your telescope - at the center of the sun, or near one of the equatorial edges, or near one of the poles...
Looks like my peak radial speed estimate was a bit low. it is more like 2000 km/hr.
Regards,
LB
=========================
As a result of the Earth's orbital motion about the Sun and the rotation of the observer about the Earth's axis the solar spectral lines are Doppler shifted relative to terrestrial standards.
Both effects give rise to Doppler amplitudes of the order of 0.5km/s.
This effect has, in the past been overlooked, with one Eastern-block group "discovering" a diurnal shift in the Telluric O2 lines by comparing them with nearby photospheric lines (which were taken as wavelength standards)!
See I.Vince, Publ. Astron. Obs. Belgrade 26, p.167 (1978) for the expose.
=========================
Finding something like that can be pretty hard. I've never actually seen such data, but I know it has to exist because the effect has to exist. And someone, somewhere, has to have measured it. Perhaps Dr Van Flandern can help you with this when he returns.
I just did a quick Google search. I got a lot of hits, but only one that seems to touch on this question. It has a reference to an article that probably contains some data, but might only be an analysis. There is no 'Net link, unfortunately.
I've included some text from that hit. I hope it helps.
It mentions an effect that I had not considered - the rotation of the Earth itself. Obviously this will add to (sunrise) or subtract from (sunset) the Earth's radial velocity and increase or decrease the observed spectral shift.
Hmmm. The sun rotates, too, so it matters where you point your telescope - at the center of the sun, or near one of the equatorial edges, or near one of the poles...
Looks like my peak radial speed estimate was a bit low. it is more like 2000 km/hr.
Regards,
LB
=========================
As a result of the Earth's orbital motion about the Sun and the rotation of the observer about the Earth's axis the solar spectral lines are Doppler shifted relative to terrestrial standards.
Both effects give rise to Doppler amplitudes of the order of 0.5km/s.
This effect has, in the past been overlooked, with one Eastern-block group "discovering" a diurnal shift in the Telluric O2 lines by comparing them with nearby photospheric lines (which were taken as wavelength standards)!
See I.Vince, Publ. Astron. Obs. Belgrade 26, p.167 (1978) for the expose.
=========================
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