One of many educational pages devised by entrepreneur and programmer John Walker, YourSky is a virtual planetarium. Visitors to the site can use the Sky Map to produce astronomical maps by entering time and date, viewpoint, and observing location (latitude/longitude and ascension/declination). The Virtual Telescope helps you to track comets and asteroids, and Horizon Views returns views of the stars above the horizon as seen from a specified observing site at a given date and time. If you aren't sure of the exact map coordinates of the city sky you desire to view, you can consult a hypertext list of major cities around the world. Want to aim your telescope at a certain planet or stellar body? There's a hypertext list of those, too. Full explanations of map colors and symbols are provided, along with links to related programs, a Sky screensaver, and more.