Why does the Earth appear flat, if it is proven to be spherical

Have you ever wondered why, despite seeing millions of beautiful images of a spherical Earth taken from space, the Earth appears flat to us? From horizon to horizon, our world looks like a two-dimensional plane. How can this be? Are the flat-Earthers actually onto something when they say the Earth is flat? Well, no—the Earth is definitely spherical, but the answer lies in how we experience the world around us and how our senses interpret what we see.

One primary reason the Earth looks flat is its immense size. With a circumference of about 40,075 kilometers, the Earth’s curvature is spread out over such a vast area that it’s nearly impossible to detect at ground level. When an average-sized human stands on the surface, the horizon is so far away that the Earth’s gradual curve becomes imperceptible. Even from high places, the curvature is so subtle over short distances that the change in angle is barely noticeable without specialized equipment.

Humans also have a relatively narrow field of vision, about 120 degrees, and when we look out, we see a flat horizon. The Earth’s curve is so gentle that, from our point of view, it seems like the ground extends infinitely in every direction. The curvature only becomes noticeable from a great height, such as an airplane or the top of a tall building. To truly see the Earth as a sphere, we would need to travel into space. From the Earth’s surface, the horizon spreads out evenly, and our immediate surroundings don’t offer enough variation in elevation for our eyes to detect the planet’s roundness

The illusion of flatness is further reinforced by the horizon line—the point where the Earth’s surface seems to meet the sky—which appears straight in most settings. This is because our line of sight to the horizon is extremely distant. Standing at the edge of a vast ocean or on a wide plain, the curvature isn’t obvious unless you’re far enough away to detect its gradual bend.

The Earth’s roundness only becomes apparent from higher altitudes. For example, astronauts orbiting the Earth clearly see the planet’s curvature. When we’re high enough in the air, such as in an airplane, we can start to see the curve along the horizon.