Venus transit 2004 - once in a lifetime
05:37 UT: Venus approaching the second contact (t2)
65 frames stacked, slight sharpening.
The image shows a very interesting effect: Around the part of venus outside the sun's disk is a faint arc visible. Inside Venus' dark side and around the sun are some sharpening artefacts visible. The arc is very unlikely to be an artefact.
The image with enhanced contrast and adjusted brightness to show the arc:
The effect has been confirmed by hundreds of observers and is also visible on images of scientific institutes. The effect becomes stronger with Venus approaching t2 and has also been confirmed after t3 with decreasing intensity. The common opinion is that the atmosphere of Venus is visible. Some refraction effect in the atmosphere lets us see the sunlight outside the sun's disk. I don't think that the effect is based on a diffusion effect - it shouldn't be bright enough to be seen through a d=5 filter.
The surface of the sun was very calm during the transit, at least in the white light. I was hoping for some impressive sunspots passed by venus, but the transit "background" didn't cooperate. At 08:06UT I captures some small spots on the sun's surface:
Setup and used gear
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