# Aberration of starlight due to

## Main Question or Discussion Point

Aberration of starlight due to....

I have read that the 20+ arcsec annual aberration of starlight is explained by special relativity, but I found no further comment.

So how is it explained in SR?
-HarryWertm

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jtbell
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Meir Achuz
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The 20 arcsec was measured and explained in 1729 by James Bradley. The explanation used only classical mechanics and the known speed of light. SR does not change this to lowest order.
The advantage of SR was that it gave the same correct result as Bradley, while ether drag theories did not.
SR predicts a v^/c^2 correction term, which has been measured quite recently.

Does anyone know where to find more information regarding Meir's noted "quite recent" measurement of the SR correction term? Googled all over but found no mention of any such result.

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Meir Achuz
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I'm sorry. The measurements I mentioned were of the relativistic transverse Doppler shift. I don't know of any measurements of the relativistic part of aberration. I guess it is too small

I'm sorry. The measurements I mentioned were of the relativistic transverse Doppler shift. I don't know of any measurements of the relativistic part of aberration. I guess it is too small
Look up relativistic beaming or apparent super-luminal motion of relativistic supernova jets. It has been observed experimentally there.

It looks like the most detailed and rigorous text on SR predictions is J. Aharoni, "The Special Theory of Relativity" 1965

Aharoni made predictions in terms of the ratio of semi-axes of projected ellipse. They differ from the classical geometric Earth orbit projection of Bradley.

$$\alpha(min)/\alpha(max) = \alpha(l=-sin\phi)/\alpha(l=0)$$

That is approximately

$$cos\phi-[cos(\phi)sin(\phi)/2](v/c) + [cos(\phi)sin^2(\phi)/3](v/c)^2 -[cos(\phi)sin(\phi)(1/6+sin^2\phi/4](v/c)^3$$

plus higher order terms

Another unverified parameter is the shape of the figure of aberration which is unique for SR compared with the Bradley figure of aberration.

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Look up relativistic beaming or apparent super-luminal motion of relativistic supernova jets. It has been observed experimentally there.
Would really prefer to know about new relativistic measurements of very historic phenomena like annual earth-orbital aberration of starlight rather than exotica like supernova jets.

the shape of the figure of aberration which is unique for SR
A bit puzzled by this. The maximal angle of aberration is slightly different for SR but isn't the minimal angle, and therefore minor axis of the elliptical "observation pattern", also different? And wouldn't the ratio of minimal and maximal axes be EXTREMELY slightly different for SR? Why not just measure the maximal angle of aberration as accurate as possible to attempt to find the second order SR correction? NASA budget too small or technology just not there yet?