the Virtual Solar Observatory (VSO) is a federated search system for solar physics images. It is a collaborative distributed solar data archive and analysis system with access through the Web.
The Virtual Solar Observatory makes it possible to access data from multiple sources. The VSO automatically sends a user's query to databases held at many sites, all over the Internet. Those sites search in parallel, and the VSO packages and delivers their answers to the user who can then refine the search or use links to access the data directly from the data providers.