A system and method are disclosed for determining geoposition of an observer. The system includes a sensor such as a wide field of view camera or telescope that can capture an image of the sky. The image of the sky is used to compile a table or list of the stars in the sky along with their positions. This table or list is pattern-matched with a predetermined list or table of stars to identify each star. In one embodiment, the distances between all stars in the image are computed and compared to star images from an atmospheric refraction model. A comparison of the measured table or list and the refraction model, using an optimization algorithm, is performed to determine the geoposition of the observer. In an alternative embodiment, a sensor capable of measuring two different frequency bands obtains two images of each star in the sky simultaneously. A difference in displacement is determined between the two frequencies for each imaged star; and a magnitude and direction of the difference in displacement is used to determine the geoposition of a body.