Page 388 - 89 history of astronomy_opt

ment of the distance of any planet fixes the
scale, and, as Venus approaches the earth
most nearly of all the planets, it used to
be supposed that a Transit of Venus offered
the best opportunity for such measurement,
especially as it was thought that, as Venus
entered on the solar disc, the sweep of light
round the dark disc of Venus would enable
a very precise observation to be made. The
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