This article or section should be merged with Attitude indicator

The term Artificial Horizon is used to describe devices that can indicate the position of the horizon when it is not possible to see the actual horizon. Typical application is found today in aircraft (attitude indicator) especially when flying in cloud as the attitude of the aircraft can be difficult to sense.

Its earlier use was much required in maritime navigation where latitude is measured through the observation of celestial bodies in relation to the horizon. The horizon in this context is a fixed number of degrees below the actual tangent at the observation point. Various devices were developed many relying on a liquid such as mercury to indicate the level plane. Obviously fog and rain whilst obscuring the horizon might still allow the Sun's position to be clearly measured.