The circle in which a plane tangent to the earth’s surface at the point of observation, intersects the celestial sphere, is called A. Visible horizon B. Sensible horizon C. Celestial horizon D. True horizon

The correct answer is: D. True horizon

The true horizon is the line that separates the sky from the Earth. It is the circle in which a plane tangent to the Earth’s surface at the point of observation, intersects the celestial sphere.

The visible horizon is the circle that is seen by an observer. It is smaller than the true horizon because of the curvature of the Earth.

The sensible horizon is the circle that is perceived by an observer. It is smaller than the visible horizon because of the effects of refraction and atmospheric haze.

The celestial horizon is the circle that is formed by the intersection of the plane of the observer’s horizon with the celestial sphere. It is the same as the true horizon for an observer at sea level.