It's really amazing that human mind can predict and tell the things without even seeing it. How come we even know and predicted the radius and things far away

It's really amazing that human mind can predict and tell the things without even seeing it. How come we even know and predicted the radius and things far away in galaxy without even seeing it. It's just amazing. Wow it just amazes you that scientist even have predicted the radius of thing and how it work etc.[1] [1] https://www.youtube.com/watch?v=zUyH3XhpLTo https://www.youtube.com/watch?v=zUyH3XhpLTo