People are small on a big sphere or earth. If you were on Google maps and zoom in, you would see that big looking city's to you are small on earth and that humans are even smaller. Were so small that...
The earth is round or a sphere really, oh columus and his crew thought that the earth was flat duh whoever asked this question is stupid
Yes, travel. Because the Earth's surface is curved, you'll notice that different constellations of stars are revealed ...
There are many ways, but the most solid is the many images of Earth taken from space.
There are several 'clues'... The curvature of the horizon. The shadow the earth casts on the moon during an eclipse.