银河系直径20万光年，光都要走20万年，人类是怎样测量出来的？
98 影片觀看·2024年3月20日
"How did humans measure the diameter of the Milky Way, which is 200,000 light-years across and takes light 200,000 years to travel?"@科学解说员小鹤
"How did humans measure the diameter of the Milky Way, which is 200,000 light-years across and takes light 200,000 years to travel?"@科学解说员小鹤