This resource is part of the Science Education Gateway (SEGway) project, funded by NASA, which is a national consortium of scientists, museums, and educators working together to bring the latest science to students, teachers, and the general public. In this lesson, students use Internet resources to learn about celestial coordinates, and how to use an emphemeris to locate planets on a horizon sky map. The sky maps are then used for outdoor observing. A more advanced application has students draw maps in celestial coordinates. The teacher's page contains vocabulary, homework ideas, materials, preparation, and classroom and assessment strategies. Educational levels: High school, Intermediate elementary, Middle school