243 years.
The event, which seems to be very exciting to some people, is hardly spectacular, amounting to nothing more than a small, dark spot moving slowly in front of a big, bright sun. It has only been recorded five times before, in the
18th and 19th centuries. In those earlier times, scientists tried to use the transit to gauge the distance between Earth and sun.
Venus is three and a half times bigger than the moon, but it is so far away it appears as only about 3% of the sun's diameter. It moves so steadily and predictably its position can be charted thousands of years ahead of time. As someone many years ago said, the universe runs ?like clockwork?, which is an allusion drawn from the invention of clocks, which work reliably and predictably thanks to beautifully designed . . .