Unveiling the atmosphere of Venus during the June 2004 solar transit
Abstract
Visual and CCD observations of Venus transiting in front of the Sun on June 8, 2004, revealed traces of the light passing through the atmosphere of the planet. As several witness of past events have accounted for [1][2], the event happens close to the ingress and egress phases, when the disk of the planet is crossing the Solar limb. The portion of atmosphere that is projected against the darker sky background appears bright, at least in part, due to refracted light (mainly).
The 2004 opportunity was the first observed by electronic equipment. Sets of several images were acquired by widely different instruments, at different wavelengths. The images were processed in order to subtract the sky background, and normalized. The brightness of the atmospheric arc was measured; its spatial structure and its variation in time are discussed. A latitude dependence of the arc brightness is clearly detected, with an intensity maximum close to the planet polar regions. Even comparing CCD images to visual observations, an investigation of the variability of the arc brightness from one event to the other encounters several difficulties, mainly due to the evolution of instruments in time. [1] F. Link, Eclipse phenomena in Astronomy, Springer Verlag (Berlin 1969) [2] H.N. Russell, ApJ 9, 284 (1899)- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #37
- Pub Date:
- December 2005
- Bibcode:
- 2005DPS....37.5718T