Google Sky compiles sky surveys from several observatories and renders them in the visible, infrared, and microwave. Like Google Maps, but looking up and not down, Sky uses the Maps code and interface and thus Mercator projection, which cannot project the northern and southern celestial poles. Using 3-dimensional projection, however, desktop app Google Earth can render these maps. http://earth.google.com

Google Sky accepts some Google Earth markup files to present customized data onto the Sky. It can also render the planets, the Moon, and the Sun at their current locations.

Companion sites similarly map and render Moon and Mars surveys.