substellar point(sub-stell -er) The point on the Earth's surface that lies directly beneath a star on the line connecting the center of Earth and star. The star would thus lie at the zenith of an observer at that point, the terrestrial latitude of which would equal the star's declination. The sublunar point and subsolar point are the equivalent points for the Moon and Sun, respectively.
substellar point[¦səb′stel·ər ′pȯint]
The geographical position of a star; that point on the earth at which the star is in the zenith at a specified time. Also known as subastral point.