The concept of the spherical Earth dates back to Ancient Greece. Seeing high mountains in the distance before lower ground, the Earth creating a circular shadow during an eclipse and circumnavigation are all evidence of the Earth's sphericity.

en.wikipedia.org/wiki/Spherical_Earth

The earliest reliably documented mention of the spherical Earth concept dates
from around the ..... A circumnavigation alone does not prove that the earth is
spherical. It could be cylindric or irre...

www.popsci.com/10-ways-you-can-prove-earth-is-round

Jan 26, 2016 ... Next time a flat-earth conspiracy theorist confronts you, here are 10 ways to prove
that Earth is spherical.

www.pbs.org/newshour/updates/7-diy-experiments-b-o-b-the-earth-is-round/

Jan 27, 2016 ... Musician B.o.B claimed this week that the Earth is flat, but how does a person
confirm the Earth's curves? Photo by REUTERS/Mario Anzuoni.

www.smarterthanthat.com/astronomy/top-10-ways-to-know-the-earth-is-not-flat/

Aug 19, 2008 ... This is because the earth is round, and not flat: .... The experiments were done
initially in order to prove that the Earth is flat. Though the first ...

nerdist.com/8-reasons-we-know-the-earth-isnt-flat/

Jan 26, 2016 ... ... aside, most of the human population is pretty sure the Earth is round. ... 8 ways
we know the Earth is round, and some you can prove yourself!

www.lhup.edu/~dsimanek/flat/flateart.htm

The early Christian Church accepted Aristotle's spherical earth. But a few
malcontents .... It is even said that he set out to prove the earth was round. That's
myth.

www.quora.com/Lets-say-I-dont-believe-the-world-is-round-How-can-one-prove-the-world-is-round-to-me

Here is Dr. Carl Sagan explaining how Greek scientist Eratosthenes figured out
that the surface ... Who was the first person to prove the Earth was round?

physics.stackexchange.com/questions/26427/what-is-the-simplest-way-to-prove-the-earth-is-round

Jun 24, 2011 ... How would you prove that the Earth is, in fact, round? ... circumference of the
Earth, already assuming its spherical shape; incidentally, the proof ...

www.physlink.com/education/askexperts/ae535.cfm

Earth from space Now that we have access to space, the easiest way to prove the
Earth is spherical is to leave it and view it from a distance. Astronauts and ...