Modern Astronomy is a data intensive science. This is true in two ways. First, some sky surveys are extremely large, making data access and analysis a challenge. This pushes astronomy towards the idea of on-line analysis, rather than “download and hack”.
Second, there is a multiplicity of data sources and data types. Combining images, catalogues, and spectra, and data from different wavelengths, is increasingly important for extracting the science from astronomical datasets. However there is danger of a “Tower of Babel” - if every dataset was in a different format, and accessed many different ways through many different web pages, it would become harder and harder to combine data, and do imaginative data mining.
One solution to this problem would be warehouse everything interesting in some giant government lab. A better solution is to build an open infrastructure based on standards. This is the idea of the Virtual Observatory (VO) initiative, which began a decade ago. It is most easily described by analogy with the World Wide Web. When browsing from one hyperlink to another, a user is able to access a huge range of documents. These are constructed by many different people and organisations, and spread all over the world, but to the user they feel as if they are inside her computer. The Web is transparent. The goal of the Virtual Observatory is to achieve the same feeling for astronomical data - that it is all available to explore in a single transparent system.
Like the World Wide Web, the VO is not a fixed system, but rather a way of doing things. The VO gives data centers a standard framework for publishing and delivering services using their data, and application writers a standard way to get at those services. The result is that it is easy for users to find, acccess, and mix-and-match data. This is made possible by standardization of data and metadata, by standardization of data exchange methods, and by the use of a registry, which lists available services and what can be done with them.
This vision is part way through completion, with many standards, compliant data services, and flexible tools. The key international forum for working towards these ends is the International Virtual Observatory Alliance (IVOA).