The comet's distance is only 44
p 110
times that of Uranus, while 'a' Centauri is 11,000 and 61 Cygni 31,000 times
that of Uranus, according to Bessel's determinations.
Having considered the greatest distances of comets from the central body, it
now remains for us to notice instances of the greatest proximity hitherto
measured. Lexell and Burckhardt's comet of 1770, so celebrated on account
of the disturbances it experienced from Jupiter, has approached the Earth
within a smaller distance than any other comet. On the 28th of June, 1770,
its distance from the Earth was ony six times than of the Moon. The same
comet passed twice, viz., in 1769 and 1779, through the system of Jupiter's
four satellites without producing the slightest notable change in the
well-known orbits of these bodies. The great comet of 1680 approached at
its perihelion eight or nine times nearer to the surface of the Sun than
Lexell's comet did to that of our Earth, being on the 17th of December a
sixth part of the Sun's diameter, or seven tenths of the distance of the
Moon from that luminary. Perihelia occurring beyond the orbit of Mars can
seldom be observed by the inhabitants of the Earth, owing to the faintness
of the light of distant comets; and among those already calculated the comet
of 1729 is the only one which has its perihelion between the orbits of
Pallas and Jupiter; it was even observed beyond the latter.
Pages:
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225