Page 616 - 89 history of astronomy_opt
P. 616
us. This should give rise either to intermit-
tence in the star’s light or else to variabil-
ity. It was by supposing the existence of a
dark companion to Algol that its discoverer,
Goodricke of York,[16] in 1783, explained
ˆ
variable stars of this type. Algol (I Per-
sei) completes the period of variable bright-
ness in 68.8 hours. It loses three-fifths of its
light, and regains it in twelve hours. In 1889
616
