You cannot state as fact that what you see in the sky is the same type of object as what you're standing on. It is an assumption.
Have you seen the surface of any celestial body? That's impossible, no one has. All we've seen are images on a screen.
Planets appear as 2D circular objects; we don't have access to the depth dimension. There's no way to tell what those objects are and what their actual shape is. Thinking they're spherical (or concave/convex/flat discs) is, again, an assumption.
The earth looks like literally every other celestial body
You cannot state as fact that what you see in the sky is the same type of object as what you're standing on. It is an assumption.
Have you seen the surface of any celestial body? That's impossible, no one has. All we've seen are images on a screen.
Planets appear as 2D circular objects; we don't have access to the depth dimension. There's no way to tell what those objects are and what their actual shape is. Thinking they're spherical (or concave/convex/flat discs) is, again, an assumption.