Planet

Animation

Planet = 0 (slider from 0 to 6.283, step 0.0010)
t_1 = 1.442 (slider from 0 to 6.283, step 0.0010)
M: (3.0 * cos(Planet), 3.0 * sin(Planet))
Sonne = (0, 0)
Erde: (cos(t_1), sin(t_1))
b = Line(Erde, M)
a = Line(Erde, M)
A, B = Intersect(k, a)
c = Segment(Erde, B)