View Single Post
  #154 (permalink)  
Old 07-May-2008, 09:22 PM
Celestial Mechanic's Avatar
Celestial Mechanic Celestial Mechanic is offline
Senior Member
 
Join Date: Jun 2002
Location: Milwaukee, WI
Posts: 4,156
Default

Quote:
Originally Posted by north View Post
Quote:
Originally Posted by Celestial Mechanic
Wrong. Most of the Sun's atmosphere, especially the corona through which the bending of starlight is actually observed, is a better vacuum than any we've been able to make on Earth.
explain
If you cannot understand an explanation as simple as that you might possibly benefit from a remedial reading course. I will try again.

The corona is very thin. It is thinner than the best vacuum we've ever been able to make on Earth. You can forget about refraction (bending) due to this source.

As for "emanations" of the Sun, light does not push light around. (There is the exception of Delbrueck scattering, but that is too small to matter.)

The deflection is proportional to the inverse of the impact parameter, that is, the distance of closest approach of the photons to the Sun. The figure of 1.75 seconds of arc usually quoted is for a photon skimming the limb of the Sun. A star whose undeflected position would appear about twice the Solar radius is only deflected half as much, etc.

A change in refractive index due to an atmosphere typically drops off exponentially and is only significant close to the limb of the body; as for your so-called "emanations", those would be expected to drop off as the inverse square of the distance. Maybe if we're lucky that could integrate over the trajectory to give inverse distance dependence but there's just one thing: if your "emanations" are pushing the starlight away the images of the stars should be deflected towards the Sun, not away from it. The path of the starlight is attracted toward the Sun so that the observed deflection of the star's image is away from the Sun.

Get thee to a remedial reading course and then get thee to a library!
__________________
Microsoft is over if you want it.

The bar has been lowered for the promotion of ATM ideas; the bar for the acceptance of ATM ideas must remain high.