Windows to the Universe is a user-friendly learning system covering the Earth and Space sciences for use by the general public. Windows to the Universe has been in development since 1995. Our goal is to build an internet site that includes a rich array of documents, including images, movies, animations, and data sets, that explore the Earth and Space sciences and the historical and cultural ties between science, exploration, and the human experience. Our site is appropriate for use in libraries, museums, schools, homes, and the workplace. Students and teachers may find the site especially helpful in their studying (and teaching!) Earth and Space sciences. Because we have users of all ages, the site is written in three reading levels approximating elementary, middle school and high school reading levels. These levels may be chosen by using the upper button bar of each page of the main site.