[填空题]
Our Sun rotates about the c :arbfjj7 7ea (proz gq2d6q vfn x8q+n9:d*8eenter of 2f fbeuo x/0glq: -u k2o4zkrgaymx,rp;c/74 the Galaxy $\left(M_{G} \approx 4 \times 10^{41} \mathrm{~kg}\right)$ at a distance of about 3 $\times 10^{4}$ light-years $\left(1 \mathrm{ly}=3 \times 10^{8} \mathrm{~m} / \mathrm{s} \times 3.16 \times 10^{7} \mathrm{~s} / \mathrm{y} \times 1 y\right)$ . What is the period of our orbital motion about the center of the Galaxy? $\approx$ $\times 10^8$
