period of out orbital motion about the center of the Galaxy
Our Sun rotates about the center of the Galaxy (MG ≈ 4 x 1041kg) at a distance of about 3 x 104 light-years (1 ly = 3 x 108 m/s x 3.16 x 107 s/y x 1y). What is the period of out orbital motion about the center of the Galaxy?