Why does it appear to be flat?

Objects or surfaces appear flat due to the way our eyes perceive light and depth. When viewed from a distance, the curvature of the Earth or other large structures is subtle and often undetectable, leading to a flat appearance. Additionally, the horizon appears straight and level due to the vast scale of the Earth compared to our limited field of vision. This optical illusion is further enhanced by the uniformity of textures and colors in our surroundings.