When two stones are thrown in a pool of water, the concentric circles of ripples intersect in hyperbolas. This property of the hyperbola is used in radar tracking stations: an object is located by sending out sound waves from two point sources: the concentric circles of these sound waves intersect in hyperbolas. An object that passes through the solar system and does not orbit is on a hyperbolic path. The path of a comet as it passes the earth is a hyperbola. Hyperbolas may also be seen in many sundials. On any given day, the sun revolves and its rays, striking the point on a sundial, trace out a cone of light. The intersection of this cone with the horizontal plane of the ground forms a conic section that at most populated latitudes and at most times of the year, this conic section is a hyperbola.