The line where the earth appears to meet the sky, creating a boundary that defines the visible extent of the landscape from a specific viewpoint.
A level line that seems to stretch infinitely in the distance, marking the transition between terrestrial and celestial space, particularly in open areas such as fields or plains.
The apparent edge of the earth, where the surface curves away, resulting in a visual division between the solid ground and the vastness of the atmosphere above.
Example:
月が地平線の上にあった。
A theoretical boundary surrounding a black hole, beyond which light and other forms of matter cannot escape, signifying the limits of an observer's ability to perceive events occurring within that region.
A point of no return in the context of a black hole, where the gravitational pull becomes so intense that escape is impossible, marking the transition between the observable universe and the unknown.
The concept that describes the boundary in spacetime where the escape velocity exceeds the speed of light, leading to phenomena that challenge our understanding of physics and causality.