Visions of Venus

The great transit was best seen with a reversed scope projecting sunspots and the outline of Venus onto a white card a short distance away.  The first sighting (positioned at about 10 oclock on the sun’s rim below) at about 6:11 pm EST on Tuesday June 5 was exciting:















The best pinhead mirror image just showed Venus and streaks of cloud but no sunspots. 

  The pinhead mirror resolution was improved by Scott’s addition of a punched hole in a card in the beam from the sun just in front of the mirror.

 I masked off the mirror with tape, leaving just a small triangular corner exposed to get a similar effect. 


John asked if diffraction, or scattering of sunlight as through gaps in tree leaves, was simply bending the light to give the image Lomonosov saw centuries ago?  L. took it to be an atmosphere for Venus.  I don’t think the light is bent that much. I think the images of light through leaves are simply umbra and penumbra shadows mixed with poor resolution pinhole images; Catalpa tree leaves do this well – see typical image below:


We did not see the rim of light which Lomonosov  saw about 250 years ago, which was genuine scattering from Venus’ CO2 atmosphere. This is what that looks like with a big telescope:

 Diffusion scattering happens on a very fine scale when sunlight hits a single spider web filament, or very fine scratches on glass. Such thin lines act like an optical grating or prism and create rainbow colors. Very hard to photograph but you can see it in these two Photoshop enhanced cell-phone images of sun and glass scratches. (I only increased the saturation and did not add any colors that were not there originally)


Diffusion is what makes waves bend around solid objects. It’s easy to see with water waves. But individual particular photons also act like waves and do bend a little around a sharp edge.  Even actual atomic particles, some as big as 70 atom Buckyballs can also show their wave-like propety and diffuse a little as they pass by an edge. It gets even stranger: human size aglomerations of carbon, hydrogen and other atoms – you and me – also diffuse very slightly when we pass close to the edge of a narrow doorway without actually touching it. The diffusion is too small an amount to be measured but it can be readily calculated. I think we get smeared by about 10E-50 meters or so. I can’t find the exact amount right now but it is somewhere in my scattered library.