I read in an essay that, light reaching Earth from the sun, at any given local Earth moment, is 500 seconds "behind" in indicating where the sun is, but that the gravity of the sun is virtually "current" in direction of attraction -- epi-center of mass of each to epi-center of mass of the other.

How, I wonder, was direction of sun's gravitational attraction detected or determined, for purposes of such a comparison?

Question

I read in an essay that, light reaching Earth from the sun, at any given local Earth moment, is 500 seconds "behind" in indicating where the sun is, but that the gravity of the sun is virtually "current" in direction of attraction -- epi-center of mass of each to epi-center of mass of the other.

How, I wonder, was direction of sun's gravitational attraction detected or determined, for purposes of such a comparison?

anonymous · Answer

Which essay "said" this exactly?  Namely that light is off by 500 seconds.... ?  I'm not saying it's necessarily wrong I'm just curious to see how they calculated this apparent phenomena.

anonymous · Answer

Reply to diracdelta: See http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html

anonymous · Answer

I see, well I am definitely not versed enough to add anything useful to the conversation because this topic goes well beyond my current understanding but I'm glad you posted this because it's definitely very interesting to think about :)

anonymous · Answer

Thank you, dirac.  I will leave this question open  for now, and will continue to pursue by reading the references provided by the essay authors, as well as any other material I can find relating to it.