> Publicity is already building to its expected crescendo on > 8 June 2004 when Venus will transit the Sun's disk...
> So how can a dialist participate in the fun? A truly fascinating question but, sadly, I suspect the answer is to use a telescope! > I notice that the six-hour event's final minutes transpire > just as the Sun culminates over Italy... Indeed so. The Italians have all the luck and it probably won't be cloudy there either! > ... the location of several marvelous meridiane. As you say these can be thought of as pinhole cameras and you can do some simple calculations... A very crude model of a pinhole camera is to think of it as constructing an image out of pixels with each pixel the same size as the pinhole. [This is crude because the pixels all overlap but you get the idea.] At the time of transit, the angular diameter of Venus will be almost exactly one arc-minute so you want your pinhole to subtend an angle no more than this if you are to stand a good chance of seeing Venus. At Milan Cathedral, for example, the pin-hole is 25.2mm in diameter (information from Gianni Ferrari whose reply will be definitive!) and for this to subtend an angle of one arc-minute you have to be about 87m away. Unfortunately the height of the pinhole above the Cathedral floor is under 24m and, being close to the solstice, the solar altitude will be high too. You are going to get only one third of a pixel or so and I don't think you will notice the smudge. Gianni: please tell me I'm wrong! Frank King Cambridge University England -
