What's the first thing that came into your mind when you see the title? A spherical planetary object that revolves around the sun? Yes.
But what if the Earth is NOT spherical? People around the world have assumed the Earth as a spherical object, but how do you know it if you never even see it?
Now, this brings back to the old "Earth is like a disc like object" theory. It might sound illogical to think that the Earth is flat, but if it was indeed, in the right amount of density and thickness, the gravity in the centre would seem normal, but as you go on the edge, the gravity would skew, as in a sense you will feel weightened in a certain angle pushing you to the centre.
Well, to think of it, if this was true, gravity will pull back all land and resulting with the round Earth, but yet again, we've never seen Earth itself, so we have the right to believe either theory. Well, an experiment to proof that the Earth was round and at the same time calculating the circumference of the Earth was done by Erastothenes in 300 BC.
Yes, this strengthen the theory that Earth was round. BUT Voliva believed that the Earth was flat and the sun was just a few miles u. Might seem insane, but if this belief was to be done using Erastothenes used the same experiment, it would still work the same.
Another thing is that there's a society that proves Earth is flat. Although it sounds weird, it still sounds pretty logical.
If Earth was flat, satellites orbits in a circular manner. The shadow casts by planets and moons could also be made by a flat disk, and as for gravity... flat Earther states that gravity doesn't exist at all.
Science rejects theory if the other doesn't explain better than the other, kinda like the abiogenesis (life comes spontaneously) and biogenesis (life comes from production of organelles) theories. To be real, both parties could solve the world's ignored unsolved puzzle.. and who knows the Earth itself was indeed flat.
To know more about the flat Earth, watch  THIS VIDEO! It gives a better understanding to it.