Here's why:
* Horizons are defined by the curvature of the Earth. The horizon is the apparent line where the Earth's surface meets the sky. It's a visual effect caused by the Earth's curvature.
* The Earth's surface is continuous. There are no gaps or breaks in the Earth's surface, so it naturally stretches from one horizon to the other.
While other things can *appear* to stretch across the horizon, like:
* Clouds: These can be large, but they are still floating in the atmosphere and don't actually touch the Earth's surface.
* The sky: The sky is an expanse of air, but it doesn't have a physical boundary or edge like the Earth's surface.
So, in a scientific sense, the only thing truly stretching from horizon to horizon is the Earth's surface itself.
