Himmelhorizont

Himmelhorizont is a German term that literally means "sky horizon" and is used to describe the apparent boundary in the sky where the atmosphere seems to meet the ground or the sea, as seen from a particular location and moment. In everyday language it refers to the visible horizon line that separates the sky from the land or water.

Geometrically, the horizon is defined by the local horizontal plane passing through the observer. Its distance depends on the observer’s height above the surface: the higher the vantage point, the farther the horizon appears. For a person standing with eye level about 1.7 meters above ground, the horizon is roughly 4 to 5 kilometers away; at an elevation of 100 meters it can be around 35 kilometers away. The curvature of the Earth explains why the horizon is not at an infinite distance.

In astronomy and navigation, the horizon serves as a reference plane for the horizontal coordinate system. An object at an altitude of 0 degrees lies on the horizon; objects above have positive altitude and can be tracked relative to this line. The term can also be used in meteorology and outdoor observation to describe the visible boundary under varying atmospheric conditions.

Factors such as atmospheric refraction, haze, clouds, and air pollution influence how distinctly the Himmelhorizont appears and can cause celestial objects near the horizon to appear displaced or partially obscured. The concept remains a fundamental reference point for observational astronomy, navigation, and experience of landscapes.