Page 558 - 89 history of astronomy_opt

In 1770 Lexell discovered a comet which,
as was afterwards proved by investigations
of Lexell, Burchardt, and Laplace, had in
1767 been deflected by Jupiter out of an or-
bit in which it was invisible from the earth
ˆ
into an orbit with a period of 5A years, en-
abling it to be seen. In 1779 it again ap-
proached Jupiter closer than some of his
satellites, and was sent off in another orbit,
558