this just appeared in the peer-review journal Physical Review Letters. I noticed the preprint of it on arxiv last year and thought it was pretty far out. Here is the revised October 2006 preprint: http://arxiv.org/abs/astro-ph/0610844 Shining light through the Sun Malcolm Fairbairn, Timur Rashba, Sergey Troitsky Published in PRL under title "Transparency of the Sun to gamma rays due to axionlike particles" (Submitted on 30 Oct 2006 (v1), last revised 19 May 2007 (this version, v2)) "It is shown that the Sun can become partially transparent to high energy photons in the presence of a pseudo-scalar. In particular, if the axion interpretation of the PVLAS result were true then up to 2% of GeV energy gamma rays might pass through the Sun, while an even stronger effect is expected for some axion parameters. We discuss the possibilities of observing this effect. Present data are limited to the observation of the solar occultation of 3C 279 by EGRET in 1991; 98% C.L. detection of a non-zero flux of gamma rays passing through the Sun is not yet conclusive. Since the same occultation happens every October, future experiments, e.g. GLAST, are expected to have better sensitivity." The relevance for us in Cosmo forum is that AXIONS if they can be proven to exist MIGHT BE DARK MATTER and this quasar eclipse experiment is a TACTIC FOR SEEING IF AXIONS ARE REAL. People are getting clever about ways to get evidence of the existence of dark matter, if it exists. I think it's exciting. The PhysWeb news site picked up on the story and had this to say: "Quasar eclipses could clarify axion mystery Physicists have devised an experiment that could clarify whether hypothetical ultralight particles called axions -- which some claimed were glimpsed in the lab last year -- exist for real. It involves using space telescopes to check whether gamma rays from a quasar billions of light years away can travel through the Sun by interacting with its magnetic field (Phys. Rev. Lett. 98 201801)." PhysWeb requires a subscription, but here is an alternative source http://www.scicentral.com/P-02phys.html called SciCentral.