I was trying to determine if light scatter through the atmosphere of Venus could be imaged once the planet was completely silhouetted on the Sun. The seeing was very stable at our observing site in a remote part of central Ontario, Canada. I performed some high-resolution imaging using an imager with very small (2.2 micron) pixels on a 150mm F12 Maksutov-Cassegrain telescope at prime focus and using a Thousand Oaks glass solar filter. I was amazed to see that the raw images clearly showed a ring of light around the planet. This final image is a stack of 72 raw images, with minimal processing.
To try and determine whether this ring was in fact the atmosphere or some sort of an imaging artifact, I compared it to a hi-res frame taken at almost the same moment by NASA's SDO (insert on right). The SDO image also clearly shows a ring at the circumference. The SDO ring is much thinner, which is what you would expect with ultra-quality optics that are completely removed from the distortions of our atmosphere. So the question remains ... is this the atmosphere of Venus or an imaging artifact of some sort?
And here are the images he sent:
Is the ring Venus's atmosphere? Or an artifact?