If the stars are seen to rise perpendicular to the horizon by an observer, he is located on the

1. The apparent motion of stars depends on the observer's latitude. 2. At the Earth's poles (North or South), stars appear to move in horizontal circles around the celestial pole (Polaris in the North, near Sigma Octantis in the South), parallel to the horizon. They do not rise or set in the conventional sense. 3. At the Equator (0° latitude), the celestial poles lie on the horizon (North celestial pole on the northern horizon, South celestial pole on the southern horizon). All stars appear to rise straight up from the eastern horizon, move across the sky in arcs perpendicular to the horizon at their highest point (when crossing the meridian), and set straight down on the western horizon. 4. At intermediate latitudes (like the Tropic of Cancer), stars rise and set at an angle to the horizon. 5. Therefore, if an observer sees stars rising perpendicular to the horizon, they must be located on the Equator.