The way in
which it was fulfilled forms one of the most striking episodes in the
history of astronomy. The comet was first seen on Christmas Day,
1758, and passed through its nearest point to the sun on March 13th,
1759. Halley had then been lying in his grave for seventeen years,
yet the verification of his prophecy reflects a glory on his name
which will cause it to live for ever in the annals of astronomy. The
comet paid a subsequent visit in 1835, and its next appearance is due
about 1910.
Halley next entered upon a labour which, if less striking to the
imagination than his discoveries with regard to comets, is still of
inestimable value in astronomy. He undertook a series of
investigations with the object of improving our knowledge of the
movements of the planets. This task was practically finished in
1719, though the results of it were not published until after his
death in 1749. In the course of it he was led to investigate closely
the motion of Venus, and thus he came to recognise for the first time
the peculiar importance which attaches to the phenomenon of the
transit of this planet across the sun. Halley saw that the transit,
which was to take place in the year 1761, would afford a favourable
opportunity for determining the distance of the sun, and thus
learning the scale of the solar system.
Pages:
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205