Marble is a Virtual Globe and World Atlas that you can use to learn more about Earth: you can pan and zoom around, and you can look up places and roads. A mouse click on a place label will provide the respective Wikipedia article. It's also possible to measure distances between locations or watch the current cloud cover. Marble offers different thematic maps: a classroom-style topographic map, a satellite view, street map, earth at night, and temperature and precipitation maps. All maps include a custom map key, so it can also be used as an educational tool for use in classrooms. For educational purposes, you can also change the date and time and watch how the starry sky and the twilight zone on the map change. Marble also features multiple projections: choose between a flat map ("Plate carré"), Mercator, or the globe.