At the time of which we are now writing,
this very important unit of celestial measurement was only very
imperfectly known, and the observations of Pound and Bradley may be
interpreted to mean that, from their observations, they had come to
the conclusion that the distance from the earth to the sun must be
more than 94 millions of miles, and less than 125 millions. We now,
of course, know that they were not exactly right, for the true
distance of the sun is about 93 millions of miles. We cannot,
however, but think that it was a very remarkable approach for the
veteran astronomer and his brilliant nephew to make towards the
determination of a magnitude which did not become accurately known
till fifty years later.
Among the earliest parts of astronomical work to which Bradley's
attention was directed, were the eclipses of Jupiter's satellites.
These phenomena are specially attractive inasmuch as they can be so
readily observed, and Bradley found it extremely interesting to
calculate the times at which the eclipses should take place, and then
to compare his observations with the predicted times. From the
success that he met with in this work, and from his other labours,
Bradley's reputation as an astronomer increased so greatly that on
November the 6th, 1718, he was elected a Fellow of the Royal Society.
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